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The Writing and printing inks through the ages

Table of Contents
Introduction
1. General
1.1 Ancient Chinese ink making
1.2 The spread of ink in the ancient world
2. Documentation of ancient inks
3. Iron gall inks
4. Printing Inks
4.1 Modern analyses of Gutenberg’s ink
4.2 Composition of Gutenberg’s inks
5. Renaissance, seventeenth century and eighteenth century inks
6. Lithographic inks
7. Advances in chemistry
7.1 Nineteenth century ink-making
7.2 A brief digression on metal pens and nibs
7.3 New writing implements
7.4 The ballpoint pen: revolution of the spheres
7.5 A new way of writing: fiber tip pens
8. New printing inks
8.1 High-viscosity inks
8.2 Low-viscosity or “liquid” inks
8.3 Screen printing and engraving inks
8.4 Specialty inks
Conclusion
Chronological bibliography
Historical and bibliographical summary

…voice hath not utter’d,
Nor ink hath written, nor in fantasy
Was e’er conceived.
Dante, Paradiso Canto 19, 8-10

Introduction

Writing – which includes all types of grapheme, ideogram, pictogram or painted symbol – has produced documents that make up the historical, spiritual and scientific heritage of mankind.

The development of better and better inks has enabled writing to become history’s major method of communication.

For many centuries, graphemes (meaning any kind of graphic symbol) were inscribed in stone and on tablets of clay or other materials; later, they were written using appropriate optical contrast media – inks – on substrates produced from plants such as papyrus, bamboo and the like, or of animal origin, like the various types of parchment and vellum. Over the last ten centuries or so, that complex vegetal and mineral system we know as paper has been far and away the most common material for writing.

The main properties that the makers of writing inks have striven to achieve over many thousands of years include color, flowability, adhesion and penetrability into the substrate, dryability and fastness or durability; in addition, inks must be odorless and nontoxic, and must not corrode the materials they are applied to.

From the mid-fifteenth century and the invention of movable type, the printing industry (though it existed in embryonic form even earlier) has spurred the development of new ink formulations, and the growth of “ink-based” communication has been exponential.

The historic and technological evolution of inks is something the public at large knows very little about: though inks have documented everything, precious few publications have attempted to describe their origins and their history for a general audience. Even this review can lay no claim to covering all of the studies and investigations that have been devoted to the topic, which because of their unavoidably technical nature are difficult for the non-specialist to understand.

1. General

Archeology shows that writing began with inscriptions scratched into the surface of stone, clay or wax tablets, and bark. Obviously, these forms of expression did not require “optical contrast” media, because the fact that they were inscribed ensured a clear contrast between the signs – the graphics – to be read – and the surface they were cut into.

With the introduction of new materials such as papyrus, parchment and, later, paper, that could not be inscribed, writing became a question of depositing contrast materials on the surface using brushes, reeds, pens and similar means.

Ink, the generic term for these contrast materials, comes from the Greek enckauston, meaning burnt, cooked, perhaps alluding to lampblack, the main source of black pigments in ancient times, which was produced by burning resinous woods and vegetable and animal waste in metal recipients over which terracotta (and later metal) cones were suspended. Smoke was collected in these cones, so that soot – consisting primarily of carbon – was deposited on their inner surfaces in the form of powdery particles of varying fineness.

Writing inks are thus preparations, generally liquid, which make it possible to apply markings to paper or other suitable materials that show good optical contrast with the substrate because they absorb more light than it does, and are thus darker – black, brown or some other color – and readily legible.

The solid components of inks (and of paints and lacquers) are called pigments: particles or grains whose composition remains unchanged during the writing or printing process, and even after drying. In ancient times, pigments were produced by grinding minerals and native earths; blue from lapis lazuli, red from cinnabar, yellow from realgar, green from malachite, and various tones of brown from earths such as Siena – or Sienna, as the pigment is often known – and other naturally occurring soils and clays (Figures 1,2,3,4,5).

The fluid that holds the pigment in suspension in the ink is called the vehicle or binder: the vehicle’s function is to transfer the pigment from the writing implement or forme – as the typeset page ready for printing is called – to the paper, and then to bind the pigment to the paper.

Dyes are natural or synthetic substances that are dissolved in the vehicle to produce colored inks of varying hue and saturation. The major types, which can be mixed to yield an enormous range of colors, are red-orange, blue and yellow dyes.

Important water-soluble red-orange vegetable dyes include alizarin, as well as purpurin, both contained in the roots of the madder plant (Rubia tinctorum), a herbaceous perennial (Figures 6,7,8). In Asia, the use of madder root as a dyestuff dates back to extremely ancient times, while the Egyptians used it to dye fabrics at least as early as 1600 BC.

To produce the dye, the madder roots are dried and ground into powder, which will keep for several years.

Another dye in the red-orange group, heamatein, is extracted from a leguminous tree, the logwood or Haematoxylon campechianum, which grows in South and Central America. It is also called campeachy because this plant originates around Mexico’s Campeche Bay. The dye is extracted by grinding the bark.

Among blue dyes, indigo was extracted from Polygonum tinctorium, or dyer’s knotweed, a herbaceous annual. Indigo can also be extracted from the biennial Isatis tinctoria, or woad, using the leaves from first-year plants. A closely related species, Isatis indigotica Fort. (Chinese woad or tein-cheing), can also be used for the purpose (Figures 9,10,11,12,13).

Yellow dyes can be extracted from Reseda luteola (mignonette, weld or dyer’s rocket), a fragrant herbaceous plant containing luteolin, a highly resistant long-lasting deep yellow coloring agent that has been used since prehistoric times, especially for dyeing textile fibers and for silk in particular (Figures 14,15,16).

1.1 Ancient Chinese ink making

According to some historians, the origin of writing fluids dates to the third millenium BC, when we are told that an ink was invented in China by Tien Tcheu, who lived during the reign of the emperor Hwangti (around 2500 BC). As the annalist Chao-Shwo-chi (approximately 1000 BC) writes, the ink sticks – “writing lacquer” – then in use were made of animal glue and lampblack, pounded in a mortar until it became a very fine powder. In this period, the quality of these lacquer soot inks was regarded as so important that it was even controlled by a government inspector.

Huang Tsung, emperor from 713 to 755 AD, was an enthusiastic maker of inks, but the most celebrated figure by far was Tsu-Min, an inspector during the Tang dynasty: his fame was so great that his name is to be found in ink recipes as late as the fourteenth century.

Another legend would have it that in 620 BC, a Korean king presented several sticks of this lacquer to the emperor of China, but no documentary evidence supports this story.

The first certain formula, described in the book Tsi Min Jao Shu by Kia-se-che (fifth or sixth century AD) for preparing inks was based on an oily vehicle. The text, which has come down to us incomplete, gives the proportions for mixing lampblack with this oil.

Later research has named one Wein Tsu, between the third and fifth century AD, as the inventor of this formula.

This permanent ink was produced from lampblack (soot from wood smoke), bound with animal glue made from skins and hides, and then mixed with sesame oil or tung oil (from the tung tree, Aleurite fordii). Some very high quality inks included additives such as Borneo camphor or even gold dust, which scented the ink and gave a special gleam to the writing.

To produce lampblack, the Chinese burned resinous woods such as fir or pine in an atmosphere with very little air, as well as substances such as animal fats and gelatin, pitch, grape vines, resin, and certain types of seed. Combustion took place in wick lamps placed inside large terracotta containers (with small holes to produce a draft) topped by earthenware cones containing a bowl of water (for cooling) in which the dense smoke was collected, forming a fine, light, velvety powder. This powder was mixed with liquid binders featuring varying degrees of viscosity in a suspension that could be used for writing.

To make the classic Chinese ink sticks, the lampblack prepared as we have just described was ground and made into a paste by adding hot glue. This paste was then rolled into small balls, which were wrapped in a cloth and heated over steam for fifteen minutes. The next operation consisted of shaking these balls in the vehicle (the glue) to distribute the pigment (the lampblack); the longer this was done, the higher the quality of the resulting product. At this point, a solution of camphor or of camphor and rosewater was added which penetrated into the balls and softened them a bit so that they could be modeled into sticks. Once dried, the sticks were stored in a dry place, as moisture would have softened the glue and caused them to crumble.

Inscriptions on the most ancient ink sticks testify to the care with which they were made: “Light glue, 10,000 pestle strokes… or 100,000 strokes!” Though the most highly prized ink came from southern Anhui, from the She district (She Xian) near Huang Shan (Yellow Mountain), where resinous pines and fir trees grow, the ink from Huizhou – the famous huimo sticks – in Hunan were also celebrated (Figures 17,18,19).

The ink sticks are rubbed gently with water against a concave stone to dissolve the ink powder; even today, the Chinese use stone slabs with a hollow to contain the necessary water. Most of these stones are the size of a hand, but there are also bigger ones; almost all are decorated along the edge and some are true works of art. Porcelain ink slabs also exist: they are often sold in wooden cases and are very highly prized.

The most costly ink slabs are those from Duanxi (around 100 kilometers from Canton) where the Mount Fuke quarries, on the banks of the Duanxi, have been worked for 1300 years.

In “Art et Sagesse en Chine”, the renowned sinologist Nicole Vandier-Nicolas (1908-1987), expressed all of the astounding vivacity and virtuosity of China’s artists of the brush; as the general Wang Xizhi (303-361 AD), known as the Sage of Calligraphy, declared in his work Preface to the Poems Composed at the Orchid Pavilion:

“Paper is the battlefield, brush is the sword, ink is the coat of mail, the ink stone is the moat that surrounds the stronghold, intuition is the general and skill is his adjutant “.

Legend has it that Wang Xizhi learned the deft wrist motions required for Chinese calligraphy through lengthy observations of how wild geese move their necks.

In the sixth century AD, the invention of block printing – printing using carved wooden blocks – gave a considerable impetus to ink-making. Highly regarded throughout the Far East, block printing is still practiced there today, along with all of the writing arts.

1.2 The spread of ink in the ancient world

It was not difficult to find black or colored mixtures for writing, even in countries like Arabia or Egypt, were fabric dyeing techniques were fairly well developed.

In these areas as elsewhere, ink was for centuries a simple mixture of powdered charcoal or lampblack and water, sometimes adding vegetable gum (gum arabic), gelatin and animal glues to create a suitable fluid vehicle for the ink.

Writings on Egyptian papyrus, the oldest evidence of which dates back to 2400 BC, indicate that a black liquid was used which, at least in the most primitive period, was prepared with lampblack and vegetable oil. Later, it would seem that ink was produced with lampblack held in suspension in an aqueous solution of gum arabic, used as a thickener to give body and the correct degree of viscosity to the ink (Figures 20, 21, 22, 23).

Some inks were extremely long-lasting, as demonstrated by the fact that ancient papyri from Egypt and Herculaneum are still perfectly legible today. Others were quite impermanent, and indeed could be removed simply by using a wet sponge: sponging and obliterating were synonymous. In these inks, the lampblack was insufficiently densened, and gum arabic, which also serves to bind the pigment to the substrate, was not used .

From Egypt, this type of ink passed to Greece and to Rome (as described in Dioscorides, III, 36). Of ancient Greek ink-making, we know very little: nothing but a phrase of Demosthenes that would seem to indicate that colored pigments produced by rubbing from some solid substance were used (τὸ μέλαν τρίβειν, Dem. de Cor. p. 313).

The Romans used and made ink, which took its name in Latin from its color: ater meaning black. A distinction was made between writing ink, atramentum scriptorium or librarium (Hor. Ep. ii. 1. 236; Petron. 102; Cic. ad Qu. Fr. II. 15.), and atramentum pictorium or tectorium, used by painters, apparently as a sort of varnish (Figures 24, 25, 26,27,28, 29,30).

In addition to black ink, the Romans also had red atramentum rubrum or rubramentum, and green atramentum viride or viridamentum.

Yet another type, atramentum sutorium, was used by shoemakers for dyeing leather; this product contained toxic substances, and indeed could be used as a poison (Cicero ad Fam. IX. 21.).

The red ink, produced by grinding cinnabar (mercury sulfide or native vermilion) or minium (red lead, or lead tetroxide) was used for the titles and beginnings of books and laws; rubrum is also the origin of the term rubric, from rubrica, or the red ochre in the inks used for the headings of laws.

The inkstand, or atramentarium, came in a variety of shapes, but was commonly cylindrical: it is believed that the most widespread type was that shown in a painting found in Pompeii, consisting of two cylinders joined together, each with its own cover.

To write on papyrus or parchment, the Romans usually used the calamus, a flexible reed sharpened and cleft at the point using a scalptrum, or penknife; as those who did not have the patience to sharpen a blunt calumus would simply change it, several (fasces calamorum; Martial, XIV, 38) were often kept near at hand while writing, stored in a case called a theca libraria. The best reeds for pen-making came from Egypt or from Cnidus.

The scribe at work was well described by Persius (Aulus Persius Flaccus, 34-62 BC), a Roman poet of Etruscan origin:

Persius,III, 10

“Iam liber et positis bicolor membrana capillis inque manus chartae nodosaque venit harundo.”

“Now we take up our book, and the two-colored parchment, well cleansed of hair, some sheets too, and the knotty reed”.

The ancients also had metal pens, with the tip cut into a cleft nib. A fair number of these pens (which were made of bronze) have been found at archeological sites, but we know that they were a rare exception among the writing implements of the time.

On parchment or papyrus, the ancients thus wrote in ink using the red pen, whose tip was split like a modern nib to make it more flexible and to ensure that the ink would flow more freely from the pen. The tip was thin and pointed if it was intended for flowing cursive scripts, or broad if used for formal book scripts with a strong contrast between thin and thick strokes. This contrast depended on how the pen was held, or in other words whether the pen point was at an oblique angle, parallel to the surface, or horizontal.

The calamus was later joined by the quill (penna), generally those of the goose; like the reed pen, the quill was also pointed and slit to make the tip more flexible.

The two instruments – reed pen and quill pen – were in simultaneous use down to the end of the Middle Ages and beyond; the term calamus, in more recent sources, also designates the quill pen.

As a substrate, the ancients sometimes used wooden tablets similar to the wax coated types (on which letters were traced with the stilo, or stylus), but thinner and smoother, and thus suitable for writing with pen and ink. Called chartae, these tablets measured around 18 by 9 centimeters, and were usually not more than 1.5 mm thick. They were cut from the trunks of young trees, and were then dried and treated so that the ink would not spread.

Cicero, Ad Qu.Jr. II 14,1

“Calamo et atramento temperato, charta etiam dentata res agetur. Scribis enim te meas litteras superiore vix legere potuisse.” “Well, this time I’ll use a good pen, well-mixed ink and superfine tablets, for you say you could hardly read my previous letter.”

Crassus had his banners marked with letters of purple ink (Dion Cassius. XL.18); the political and commercial inscriptions on the walls of Pompeii were written in red, while in a later period, Suetonius says that a part of the poems which Nero recited at Rome (Ner. 10) were written in gold or gilt letters (aureis litteris) and consecrated to Jupiter Capitolinus.

Caked ink on the pen point was a source of irritation, as it is today; Persius (Sat. III.14) represents a foppish writer sitting down to compose, but the ideas will not flow freely…because neither will the ink! But he’s afraid that adding water to dilute the ink will make things even worse.

Persius, Sat. III, 14

“…nigra sed infusa vanescit sepia lympha: dilutas querimur geminet quod fistula guttas.”

“…thinned now with water, the black fades, and we complain that the pen spits double dots upon the page”

In the Imperial period, poets whose work was not appreciated were commonly told:

“Wipe it all away with the sponge, tedious man, and leave the Muses in peace ”;

Caligula (Suetonius, De vita caesarum, Cal, I. 20) even forced poets who did not meet his favor to erase their work by licking away the ink:

“scripta sua spongea linguave delere iussos…” “…ordered to erase their writings with a sponge or their tongue…”

To produce an ink, the black pigments are, as we described earlier, “dispersed” in binders or vehicles. These substances, which thickened the aqueous mixture, differed according to geographical area and period: glue from horns and hooves, fish glue, egg whites, honey, gum arabic, linseed oil heated to varying degrees of thickness. Perfumes were often added to hide the objectionable odors of the organic ingredients. Ink was sometimes sold in the form of glutinous cakes which were dissolved, or “tempered”, as it was called (hence the name of the dry tempera paints still used today) in water just before use.

Hebrew scripture mentions a substance called deyo, also cited in the Book of Jeremiah (XXXVI, 18: “Then Baruch answered, He pronounced all these words unto me with his mouth, and I wrote them with “ink” – deyo – in the book”), which may well have been a writing material similar to ink. According to Bernheimer, it was a black liquid, but differed from another, better known, black liquid for which the Greek term kalkantos was used. Deyo may have been a mixture of lampblack and resins which was then dried, as described in later reviews of Hebrew texts (Figure 31). It was diluted in water when the time came to use it. Later, honey and even nut gall were added to the mixture.

Other recipes for writing materials were also known. We have mentioned, for instance, inks containing cinnabar (mercury sulfide), minium (red lead, or lead tetroxide) and other mineral coloring agents, which are difficult to hold in solution in the vehicle, as they are very heavy and thus prone to precipitation.

Ink consisting of lampblack, water and gum arabic was in general use for writing on papyrus, as Vitruvius and Pliny both testify. This has been confirmed by chemical analysis of the inks on the papyri found at Herculaneum.

According to Pliny, atramentum was made in various ways: chiefly with mixtures of soot, burnt resin or pitch, in furnaces which did not allow the air to escape (Plin. II. N. XXXVI. 5. s. 25.). Others made a kind of ink by boiling and straining the lees of wine, according to the statements of Vitruvius (Vitruvius VII. 10). The black matter secreted by the cuttlefish – sepia – was also used as atramentum (Cic. de Nat. Deor. II. 50 ; Persius, Sat. III. 12,13 ; Ausonius, IV. 76.). Pliny also observes that an infusion of wormwood with ink preserves a manuscript from mice.

2. Documentation of ancient inks

As Pliny the Elder (Caius Plinius Secundus, 23-79 AD) tells us, the Romans were familiar with an embryonic form of iron gall ink: in a solution of green vitriol (ferrous sulfate, an iron salt), they poured a decoction of oak galls (an excrescence on oaks caused by insects) together with pomegranate rinds, obtaining a black pigment that could be used for writing. This would appear to be the atramentum sutorium we mentioned above.

Philo of Byzantium (280 BC-220 BC) refers to an invisible ink (also called sympathetic ink) consisting of extracts of galls that was used for writing; it remained invisible until green vitriol was applied to the sheet. The writing then turned black, and could be read. Pliny writes of the tithymalum – a kind of spurge called at the timeherba lactaria (milk plant) or lactuca caprina (goat lettuce) – which, he said, could be used as an invisible ink that worked in a different way: letters written with the milky sap of this plant would not be visible until dry and powdered with ashes.

Ovid (Publius Ovidius Naso (43 BC – 18 AD), in his Ars Amatoria or The Art of Love (Ars. Am. III.627) recommends writing with milk, unreadable until sprinkled with coal dust, which would stick to the slightly fatty surface left by the milk.

Ovid, Ars. Am. III 627-28

“…Tuta quoque est fallique oculos e lacte recenti Littera: carbonis pulvere tange; leges…”

“…writ in fresh milk, all’s safe and the eye deceived; dust it with coal, and you will read…”

The Christian Latin poet Ausonius (Decimus Magnus Ausonius (ca. 310–395) gives the same advice (Epist. XXIII.21).

Inks of other colors used in antiquity included the sacrum encaustum, made with the purple pigment extracted from the hypobranchial glands of marine mollusks of the genus murex, added to water.

The pigment which produced this purple color was made by drying two species of the Murex snail (Murex trunculus and Murex brandaris) found in Mediterranean waters. One of the two species yielded a turquoise blue secretion; the other, a light red secretion. These dyes were mixed to produce a variety of colors, all highly prized. The snails were ground and left to dry in the sun for three days, and then boiled for ten days in lead pots. As around 12,000 snails were needed to extract a few grams of pigment, purple was enormously expensive (Figures 32, 33, 34, 35).

The first to use this method to produce purple pigment were the Phoenicians, who used it to dye cloth. For the Romans, purple was a symbol of power: the emperor wore a purple tunic, and senators were allowed to wear a tunic with a broad purple stripe.

Purple-red inks could be used only by the emperor to write his signature, and were forbidden to common mortals except for the emperor’s sons and near relations to whom privilege was expressly granted.

In the Middle Ages, the use of sacrum encaustum was restricted to reigning monarchs. The gospels were written on purple parchment, in gold and silver inks, made by mixing fine metal powders in wine (which acted as a mordant) together with gum arabic or albumen.

Parchment was dyed purple, blue or even black. Many of the gospels copies between the fifth and seventh centuries are written on a purple ground whose various methods of preparation are described in medieval codexes: the Miscellany codex 87 in the Chapter Archives of Vercelli, the Codex 490 in the Chapter Library of Lucca, and the fifth century Codex Purpureus Rossanensis, or Rossano Gospels, now in the cathedral of Rossano Calabro.

Use was also made of the so-called blue of Alessandria, i.e., powdered copper treated with sand and saltpeter, which yields light blue copper nitrate; over time, this pigment tended to turn green as carbon dioxide in the air converted the copper nitrate to copper carbonate, or artificial malachite.

A substitute for gold was auripigmentum, consisting of yellow arsenic trisulfide (As2S3, the mineral orpiment), which is not poisonous because it is insoluble; it could also contain sandarac, or golden arsenic disulfide (As2S2, now called realgar), which becomes orpiment when heated.

Nor must we forget the treatise by Heraclius or Eraclius, De coloribus et artibus romanorum, an important source for the history of dyes, pigments and the “technical” arts in general. The work is divided into three books: the first two in verse, and the third and longest in prose.

The second section is entitled “On the use of the fresh juices of plants in miniature painting”, and provides detailed descriptions of how to prepare pigments and dyes for manuscript illuminations and colored inks.

The oldest treatises on colors, pigments and paints written in the late Roman period are difficult to place precisely in the historical framework, as few sources that have survived; the emperor Diocletian, in fact, ordered the destruction of an enormous number of alchemical works and the like, for fear that someone would be able to transform base materials into gold.

Later medieval transcriptions of such recipe books (which have often come down to us incomplete) probably enjoyed a rather limited circulation, both because they were written in Latin (of varying quality), a language that was not widely used among artists (think, for example, of Leonardo da Vinci, who called himself, regretfully, “homo sanza lettere” – an unlettered man – because he knew no Latin), and because the few copies that were made were conserved in monasteries to which relatively few people had access. In addition, each copyist could introduce whatever variations the patron of the moment might happen to want, thus breeding errors and misreadings that were passed on without question.

Many colors of ink were used during the Middle Ages (as in the ninth-century codex Vatic. Reg. lat. 129): red, blue, yellow, gold, silver, green, white. Many curious recipes for preparing these inks can be found, and are interesting to record here.

Some of the oldest of these recipes to have survived are the formulas contained in the Schedula diversarum artium by the monk Theophilus Presbyter (XI-XII century). To prepare encaustum, he prescribes a dried and powdered extract of the bark of certain plants mixed with green vitriol (copperas, or ferrous sulfate), or a mixture of powdered iron and tannin. He also recommends that gold, silver and copper inks be prepared by pouring the powdered metal into decoctions of oak apples, vinegar, wine, or gum arabic in water. Theophilus also knows of a “Spanish black” used for a species of lacquer similar to Chinese ink; for red, he uses minium (lead tetroxide, or red lead) and carmine (cinnabar, mercury sulfide), while his white is ceruse (lead carbonate, or white lead). These substances, dissolved in egg whites, vegetable gums (tragacanth, other gummy saps, etc., serving as binders and dispersants), in wine or vinegar, or in plant juices (acting as mordants, and improving adhesion), were also part of the formulations used in miniature painting.

The Miscellany codex 87 in the Chapter Archives of Vercelli and the Codex 490 of Lucca contain similar formulas for the so-called chrysography, or writing in gold.

A fifteenth century manuscript entitled “Segreti per colori” – Secrets of Colors – now housed in the library of the University of Bologna provides us an idea of the state of protochemistry in the Italy of that day. The work is divided into eight chapters; it discusses blue, and lapis lazuli or ultramarine blue in particular, and the various ways of producing it. In the third chapter, after describing how to make blues with the juices of several plants, it turns to a number of dyes, including indigo dye and the methods for producing it from woad. The fourth chapter teaches a number of ways of preparing verdigris or copper green, the most singular of which recommends that the color-maker “… place copper sheets in vessels under manure, then after one or two months, treat the product with the strongest vinegar and cover the vessels with manure once again. After two months more, the copper green (basic copper acetate) is ready”.

Chemically, what happens here is that the copper reacts slowly with the acetic acid in the vinegar: this produces a greenish salt, while the hydrogen sulfide fumes – aka sewer gas – arising in the manure heap can accelerate the process.

In the Middle Ages, ink making was largely the work of monks, who for centuries made up the ranks of the scribes to whom history owes its undying gratitude for the recovery and preservation of much of Western classical culture and the chronicles of its events. Take, for example the long parchment scroll, dating from the eleventh century, called the Chronicon Novaliciense, at the Abbey of Novalesa in Piedmont, founded by Charlemagne (who among his many other merits did much to promote writing), which narrates the life and doings of the abbey in the centuries that only those who do not know their history call the “Dark” Ages”.

In the monasteries, ink was prepared according to traditional formulas, which were often jealously guarded secrets. There were also specific rules for storing ink.

By the late Middle Ages, lampblack ink had begun to lose its importance; we hear of it only in the treatises of the painters and illuminators of the period, who used it in small quantities as a pigment in their paintings.

Lampblack ink has the valuable property of not being reactive, thanks to the fact the carbon used in it is chemically inert: it is not subject to chemical changes with the passage of time, and contains no substances that can damage the substrate to which it is applied. In addition, the carbon particles do not fade in light: in other words, they are lightfast. However, this type of ink has two serious drawbacks which doubtless limited its use: it tends to smudge in moist environments because it does not penetrate deeply into the substrate, and, consequently, it can be washed off, or even removed by rubbing or scraping, by anyone who intends to alter a piece of writing. This latter aspect may have led to the practice of adding small amounts of ferrous sulfate, which over time is subject to slow chemical reactions that transform it into a variety of iron oxides, leaving dark brown deposits. The highly soluble ferrous sulfate penetrates into the paper, leaving these deposits, which are not readily removed. As a result, the writing is very difficult to erase.

Washing a document written with this type of mixed (lampblack and ferrous sulfate) ink will only remove the carbon particles on the surface, while the ferrous sulfate deposits will remain. Even scraping will not be fully effective in removing the writing without damaging the surface of the sheet, given the iron salt’s deep penetration.

When larger and larger amounts of ferrous sulfate are added, however, the brown from the iron oxides overwhelms the black from the carbon particles.

This problem could be avoided only when the reaction between tannin (gallotannic acid) and iron salts had been understood. As adding galls (which contain this tannin) turned the ferrous liquid black, a mixture of carbon ink and iron gall ink would not change color over time.

This is one of the theories that have been advanced concerning the birth of iron gall inks, which were thus developed later than lampblack-based carbon inks. Their use began to spread in the Middle Ages, though there is no lack of earlier mentions.

3. Iron gall inks

The chemical reaction between tannin and iron salts (ferrous salts, i.e., at a lower oxidation state than ferric iron) has been known since antiquity. The oldest extant Greek mentions of it are found in the Leyden Papyrus and in the Stockholm Papyrus. Pliny the Elder describes an experiment in which he wet a papyrus that had been soaked in an infusion of tannin with a solution of iron salts: the papyrus immediately turned black.

Several hundred years later, Martianus Minneus Felix Capella (fifth century), a native of the Roman province of Africa who appears to have practiced as a jurist in Carthage and became a writer late in life, composed a sort of encyclopedia that achieved canonical status during the Christian Middle Ages, De nuptiis Mercurii et Philologiae (“The Marriage of Mercury and Philology”), in which he supplies a formula for preparing an ink that he calls “gallarum gummeosque commixtio”. This ink was produced by mixing varying proportions of an infusion of galls, tannin-rich growths which develop on certain trees (oaks, for instance) when insects deposit their eggs in the plant tissue, green vitriol (ferrous sulfate) and gum arabic (the latter being used as a binder to hold the pigment in suspension). The formula that Albertus Magnus gives in his De rebus metallicis is of the same kind.

Iron gall ink was widely used in the Middle Ages, though the first known recipe is contained in the treatise by Theophilus Presbyter we mentioned above. In the West, its use was virtually universal, and many variations can be found from the fifteenth century onwards. Iron gall ink was employed in writing an enormous number of documents, as well in printing woodcuts.

This ink’s color is due to its main component, ferrous gallate, which forms when a generic tannin reacts with a ferrous salt. The reaction takes place with precise quantities of tannins and metallic salts (molar ratio of 4 to 1); all of the iron combines with the tannin, forming a complex with it that produces a chemically stable ink where the ferrous gallate acts as a pigment. Under these conditions, however, the reaction proceeds fairly slowly, and it thus takes time to reach completion. The ink would behave as a coloring agent, becoming indelible, only if it was used immediately after it was prepared. With the proportions we have indicated, moreover, it took a few seconds of exposure to the air for the iron in the compound to oxidize completely and turn black. For this reason, there was a tendency to add an excess of metallic salt beyond that required to combine with the tannin: though this ensured that the ink would turn black immediately, it also made the compound unstable. It should also be borne in mind that while the ink would stay black for a considerable length of time, once all of the excess iron had oxidized, it would turn brown, and this is thus the color we find on most antique manuscripts. Not only does the excess ferrous iron turn the ink brown as it oxidizes, the oxides then tend to crystallize, forming hematite (ferric oxide) microcrystals that appear as iridescent flakes. These reactions, together with the acid properties of iron gall ink, can damage the cellulose in the paper to the extent that the ink may even burn holes through the areas where writing was applied.

The public and private documents written in “tanno-gallate of iron” preserved in the world’s archives and libraries testify to the widespread medieval use of iron gall inks, which became even more common from the twelfth century onwards. These inks were usually low in grade and of poor quality: a muddy fluid, easily precipitated, which deteriorated quickly. A length period of experimentation was needed to modify or overcome its defects, as well as to gain information about the different tannins, the proportions of each constituent, and the correct methods of preparation. From the recipes that have been found, we can say that the raw materials and methods used varied widely, with those that were chosen depending on geographical area, personal convictions and the materials at hand (Figures 36,37,38,39,40).

Tannins vary in composition; some are polyphenols of moderately complex structure; others also contain esters of glucose or other sugars. When exposed to light, the color of tannin becomes more intense. They are water-soluble compounds: tannin is usually extracted from infusions with water or water and ethanol. As the latter evaporate at low temperature, the tannin is precipitated from solution.

A recipe contained in a codex dating from 1412 and published by Ebert (Zur Handscriftenlkunde, Leipzig, 1825, page 35) recommends mixing powdered nut gall with water or beer and then subjecting the mixture to the reaction of green vitriol (ferrous sulfate). This basic formula remained almost unchanged in later centuries, and was often applied empirically, i.e., without any rational or uniform way of establishing the proportions of each ingredient. The Liber illuministarum pro fundamentis auri et coloribus ac consimilibus, written sometime in the 1500s at Tegernsee, near Munich, and now in that city’s Staatsbibliothek), contains a recipe for ink which it summarizes in a Latin distich, or couplet:

Integra sit galle, media sit uncia gummi

vitrioli quarta. Apponas octo falerni.

Thus, the recipe calls for: nut gall (one full ounce), gum arabic (extracted from several species of acacia and soluble in water, half an ounce); iron vitriol (one quarter of an ounce), and eight ounces of Falernian wine, celebrated since the time of the ancient Romans.

In the sixteenth century, the composition of iron gall inks achieved a certain uniformity all over Europe, thanks to the standardizing influence of the Florentine inks then in widespread use. Throughout the fourteenth, fifteenth and sixteenth centuries, in fact, Florence led the rest of Europe in ink making, producing more and better inks than anywhere else.

In the 1500s, after the advent of printing with movable type and the more extensive use of the vernacular rather than Latin, “books of secrets”, or collections of recipes and practical techniques of all kinds, began to enjoy wide popularity. An interesting theory holds that this was due to the need to use manpower that did not have the skills that the lengthy apprenticeships required by the hidebound old system of guilds had ensured: when the mercantile middle classes took the reins of trade in the sixteenth century, the new workers had no longer received years of training under a master. Hence the need for handbooks that could explain what once had been the secrets of each craft.

The first examples of these new compilations of recipes in the vernacular appeared in Germany, but some of the most famous were published in Italy, including “I segreti del reverendo Alessio Piemontese” attributed to Girolamo Ruscelli (Viterbo 1504 – Venice 1566), which went through 104 editions in at least seven languages (Italian, Latin, English, French, German, Spanish and Flemish) in the space of little over a century. Ruscelli’s authorship is certain, as the title page of a Venetian edition of 1567 reads “Secreti nuovi di maravigliosa virtù del signor Ieronimo Ruscelli i quali continovando a quelli di donno Alessio, cognome finto del detto Ruscelli, contengono cose di rara esperienza, & di gran giovamento” (New secrets of marvelous worth by Master Ieronimo Ruscelli, which continuing after those of Father Alessio, assumed name of said Ruscelli, contain things of rare experience and advantage). The treatise was enormously successful, as witnessed by its many printings and by the fact that it provided the material for many recipe books published in the course of the seventeenth and eighteenth centuries.

An eighteenth century edition dated 1783 and printed in Venice by Francesco Locatelli under the title “Secreti del reverendo D. Alessio Piemontese, divisi in quattro parti. Nuovamente ristampati e da molti errori ricorretti” (Secrets of the Reverend Father Alessio Piemontese, divided into four parts. Newly reprinted and purged of many errors) describes a number of curious uses for pigments and dyes. For example:

– To dye a white dove gold: “Take saffron, well ground and pounded, and mix it with bile from the Luce, and with this color the bird”. Saffron is expensive, but less than gold, which it resembles in color, while the bile of many fish (the pike, in this case) does in fact have an adhesive effect and, once dry, leaves a shiny surface.

– To make black dye to color a horse: “Take pounded gall, and make distilled water of it, and with this dye a white or sorrel horse, and it will become black; and to give a black horse a white blaze, take the droppings of chickens, place them on the face of the animal for a day, binding them well, and then remove them, and where the droppings were, there it will be white.” The tannins from the gall dye the horse’s coat, but the effect of chicken droppings is something that the chemist is hard pressed to explain – much less believe.

Other authors such as Leonardo Fioravanti and Domenico Auda were also widely read, and were still copied as late as the nineteenth century, but the recipes they offer were far less “innovative”.

Any one of the recipes in these books of secrets, that provided by Pietro Maria Canepario in his 1619 treatise “De Atramentis cuiuscumque generis”, for instance, can be taken as an emblematic example of the seventeenth century method of preparing iron gall inks:

“For four days, mix four pound weights of white wine, a cup of the strongest vinegar and two ounces of crushed gall. These then are cooked over the fire until a quarter has evaporated. Then strain the liquor and afterwards add chips of gum arabic, two ounces, mixing well and returning to the fire so that it boils for as long as it takes to say three paternosters. Take it then from the fire and add three ounces of ground Roman vitriol, stirring the while with a stick until it is almost cold. Then pour it into a glass cup, kept well away from the light and air. After it has stood in good weather for three whole days, it can be strained and used.”

As can be seen, the main ingredients were always the same: a tannic substance of some kind, iron salts, solvent, and a binder-emulsifier such as gum arabic.

The method of preparation consisted of extracting the tannic and gallic acid from the galls, which for this purpose were crushed and left to steep in the solvent (water or wine) for a week, and then boiled. At times, the galls were boiled without steeping them first in solvent. Boiling continued until two thirds of the solution had evaporated, reducing it to one third of its original volume. The iron salt was then added, and reacted with the tannic and gallic acids. The emulsifier was added at this point (though it was sometimes added before the iron salt) to hold the black particles that formed through the chemical reaction in suspension. Other additives to increase fluidity, prevent fermentation, or scent the ink could be used as needed, as we mentioned earlier.

The inks produced in this way, however, were excessively acid. The reaction that forms ferrous gallate also frees sulfuric acid from the ferrous sulfate, which remains in solution and, over time, will corrode the substrate to which it is applied, paper in particular, and may even eat holes right through it. This excessive acidity is characteristic of the writings preserved in Italy’s archives, which have an urgent need for costly and time-consuming restoration as a result

This acidity was compounded through the use of vinegar, added for its acetic acid content, and of wine, added for its ethyl alcohol content, both of which served to improve the solubility of the ferrous gallate pigment and help it penetrate in the paper, mordanting it into the fiber.

During the sixteenth century, a number of writers give details of the better-known methods and procedures. The celebrated mathematician and mechanical experimenter Girolamo Cardano (Pavia 1501 – Rome 1576) in hisDe subtilitate, libri XXI (Basileae per Lvdovicvm Lvcivm, Anno 1554), and De Rerum variegate, libri XVII (Basileae 1581, per Sebastianum Henricpetri), suggests recipes and different types of black and colored ink, demonstrating that Renaissance scientists had to do a bit of everything to make ends meet.

Alessio Piemontese, whom we have already introduced as the pseudonymous author of De secretis libri septem (1557) give recipes for black (decoction of gall, white wine, copperas and gum arabic), for other colors (made with Brazil wood, tin oxide, purpurin and stannic sulfide), as well as for gold and silver paints made from the powdered metals or using stannic sulfides and mercuric sulfide as pigments.

These were often highly toxic mixtures, to which even more potent poisons could be added (deadly salts and soluble oxides of arsenic, for example, or gut-wrenching antimony) for all manner of unnamable purposes and foul ends, as portrayed with massive doses of suspense in recent bestsellers and various efforts at fictionalized history.

An erudite and highly philosophical work on colors and their historical and social importance was penned by the humanist and poet Antonio Telesio (1482 – 1534), who latinized his name as Antonius Thylesius (Antonii Thylesii CosentiniLibellus de Coloribus, ubi multa leguntur praeter aliorum opinionem); the learned author, however, has nothing of technological relevance to offer, limiting himself to discussing the improbable influences of colors on human destiny.

Giovan Battista della Porta, polymath of markedly esoteric interests (Magiae naturalis libri viginti, 1567), resuscitates Pliny the Elder’s recipe for sympathetic ink, recommending a decoction of gall nuts for making letters reappear that had been written in Roman vitriol (ferrous sulfate), practically invisible on paper until brushed with the gall solution that causes the black iron salts to form. Other types of sympathetic ink mentioned by della Porta include certain plant juices that become visible when exposed to heat (because of the formation of tarry substances occurring as a result of thermal cracking, i.e., the partial combustion or degradation of thermally unstable molecules); a clear liquid that turns white when the paper is heated and charred (probably as a result of the dehydration of a salt which is colorless in the hydrated state), or black if black powder is sprinkled on it (because the powder, which presumably contains a little glue, gelatin or gum arabic, sticks to the letters).

An indelible ink made with oil and lampblack is mentioned by Johann Jacob Wecker (De secretis, Basle, 1582), quite a believable formula, since lampblack is well known to be impossible to remove if well anchored to the substrate, which can be achieved through the use of animal glue or even isinglass, added in small quantities to the mixture so as not to detract from the ink’s fluidity.

Several recipes for inks based on gallotannic acid are found in Hebrew texts from the sixteenth century: one, for example, calls for one ounce of gum arabic dissolved in white wine and two ounces of copperas, to which three ounces of gall in thirty of white wine were added. The copperas solution was boiled, and the gall solution poured into it, to produce the black pigment. As wine, however, was prohibited by rabbinical law and Hebrew tradition, the authors who reported this formula must have found that it had little to recommend it.

The main characteristics of iron gall inks continued to vary widely for many years, until, in 1626, the French government concluded an arrangement with ink makers to standardize production and thus guarantee quality. Other governments later followed suit with similar agreements.

After this, improvements to traditional formulas proliferated, from those by Otto Tachenius (Hippocrates Chimicus, 1666), to the work of the famous chemist Robert Boyle (originator of Boyle’s Law of the behavior of gases), who attempted to explain the reactions that take place when copperas is added to infusions of gall in Some considerations touching the usefulness of experimental Natural Philosophy (Oxford, 1763).

Here, I would like to record a typical eighteenth century formula for writing ink hailing from my own home region of Piedmont, which I found in a manuscript by an otherwise unknown priest, one Father Brocero of Savigliano, near Torino; it calls for:

Roman gall, three ounces,

Rock alum [hydrated aluminum sulfate] one half ounce; gum arabic, one ounce;

Copperas [hydrated ferrous sulfate], two ounces.

These materials are crushed, placed in one brenta (50 liters) of rainwater (essentially, distilled water) and left for eighteen days in the sun: an ecological way of evaporating the excess liquid. A little spirit (ethyl alcohol) is added, and the whole is filtered. The alum, or aluminum sulfate, is used as a mordant to anchor the ink to the cellulose fibers in the paper.

To conclude our discussion of iron gall inks, then, we can say that from the sixteenth century onwards, there was a certain uniformity in the composition of writing inks throughout Europe, thanks to the standardizing efforts of monks, craftsmen, merchants, alchemists and governments. In their celebrated (1751-1772) Encyclopédie ou Dictionnaire raisonné des sciences, des arts et des métiers, Diderot and D’Alambert illustrate the art of writing with the classic goose quill, still used for special documents and appreciated by purists of calligraphy today (Figures 21, 22, 23, 24).

Iron gall ink’s relative indelibility also ensured that it was also universally used as “safety ink”, as it is in fact difficult to remove completely from the substrate, even by scraping. The discovery of the bleaching power of chlorine in the eighteenth century made it possible to erase iron gall inks, though only temporarily: bleached, the ink loses its color, but after some time, the oxygen in the air re-oxidizes the iron, and the writing reappears, much faded but still legible.

To prevent chlorine from having this effect, the Swiss maker Leonhardi developed a formula for a safety ink that combined the properties of iron gall ink with those of active dyes in an acid solution, which would not lose their color when oxidized by chlorine.

Iron gall ink began to fall into disuse in the early twentieth century after the introduction of pigment-based India inks, which did not damage steel pens (readily corroded by the sulfuric acid in iron gall ink), and disappeared entirely with the invention of the ballpoint pen, which use an oil-based ink similar to printing inks.

In 1990, Russian scientists discovered the composition of a very old (probably seventeenth century) and highly prized Tibetan writing ink, known as the “Ink of the Seven Gems”, used in the sacred manuscripts of the Buddhist monks of that country, then (in the 1600s) virtually unexplored. Using modern analytical methods, it was determined that this ink contained gold, silver, copper, coral, lazurite (a component of lapis lazuli), malachite and mother of pearl. Not exactly economical, but its iridescence on shellacked paper is almost incredible.

4. Printing inks

Letterpress printing (Figures 41,42,43,44,45,46,47,48,49), or in other words, printing text with movable type, probably arose in Germany through the work of Johannes Gensfleisch, known as Gutenberg, and his followers around 1440.

The inks we have described so far, whether iron gall-based or aqueous solutions of gum arabic containing lampblack pigments in solution, cannot be applied uniformly to metal type, as they are too fluid and thus tend to smear or run, rather than spreading evenly so that they transfer cleanly and legibly to the paper.

Gutenberg thus had to use oils, which adhere more effectively to metal type. It is thought that, initially, oils were added to iron gall ink, but there is no evidence to support this conjecture.

Very little historical evidence of any kind, in fact, is available concerning the first printing inks. Nevertheless, it should be emphasized that the ink in the celebrated 42-line Bible (1450-52) is essentially perfect, undoubtedly the result of lengthy research which links Gutenberg to the Flemish masters who pioneered the use of oil paints (with linseed oil) in the fifteenth century. Thus, the first printed works employ dense black inks that are free from the brownish overtones that are still to be seen in many works dating from later centuries.

In his De inventoribus rerum, Polydore Vergil maintains that printing ink was invented by Schoeffer, but it is certain that Gutenberg himself formulated his own ink: he could not have printed the first Bible so perfectly without a good ink, whose formula was thus not something that could simply be extemporized.

Another, less reliable tradition would have it that printing with movable type was invented around 1440 in the Netherlands by Laurens Janszoon Coster of Haarlem, who could easily have had contacts with the world of Flemish painting.

In general, early printing inks consist essentially of two components: a black or colored solid pigment, and a viscous or pasty fluid called varnish which acts as a vehicle and binder for the pigment so that it can be used to ink metal type.

The pigment must be perfectly ground, or in other words reduced to extremely fine powder and mixed uniformly in the varnish.

The resulting mixture, dense to the point of stickiness, was spread onto the type, originally with a gloved hand, and later usingink balls made of leather stuffed with wool or hair and attached to a wooded handle.

In the first printed books, or incunabula, the chapter initials were hand-colored – or rubricated – with the usual tempera paints. Soon, however, red and blue inks came into use, made by mixing the linseed oil with cinnabar (for reds) and lapis ultramarine or azurite (native copper carbonate) for blues.

A document dating from the late fifteenth century in the Diario della Stamperia di Ripoli lists the materials purchased by a printshop run by the nuns of the Florentine convent of Ripoli. Consequently, we know that the convent bought linseed oil, turpentine, resin and linseed varnish, solid or liquid according to the season, as the temperature has an enormous influence on printing ink: the hotter the weather, the more viscous the ink must be.

Turpentine (made by distilling the wood and sap of conifers) was heated until all of the volatile content had evaporated, leaving rosin, a solid resin also known as Greek pitch or colophony – from Colophon in Lydia – which gives body to the ink so that it does not spread on the page or leave black spots or halos around the printed lines; using too much resin, however, will produce an excessively tacky ink that can cause the paper to dry and tear prematurely.

A typical recipe for early printing inks calls for three parts of lampblack, ground together with around 15 parts by weight of boiled linseed or walnut oil. Every morning, the pressmen would have to prepare the amount of ink they would need for the day, as both linseed and walnut oils are drying oils or driers that limit the amount of time that the ink remains at the right consistency for printing.

According to Stoyle, in his preface to C.H. Bloy’s A history of printing inks, one of the major texts in this area, the lack of information about early inks is due to the printers’ marked reluctance to disclose the secrets of their art. Each of the most celebrated printshops, in fact, guarded their knowledge with care, often obliging their workers to swear oaths of secrecy and threatening those who disclosed the master’s formulas with dire punishments and terrifying reprisals.

This newfangled new business of printing is rather oddly illustrated in one of the plates in the Novo teatro di machine et edificii : per uarie et sicure operationi; có le loro figure tagliate in rame é la dichiaratione e dimostratione di ciascuna; opera necesaria ad Architetti, et a quelli che di tale studio si dilettano, (the New Theater of machines and buildings: for safe and divers operations; with their representations engraved in copper and the statement and demonstration of each; a work necessary for Architects and those who delight in this study) published by Vittorio Zonca of Padua in 1656 (Figure 28). More accurate, and of greater technical interest, obviously, are the plates in the first great encyclopedia, the Encyclopédie ou Dictionnaire raisonné des sciences, des arts et des métiers, published a century later by Diderot and d’Alambert between 1750 and 1770, which depict letterpress printing (Figure 29), the printing press and associated equipment, and the copperplate press.

4.1 Modern analyses of Gutenberg’s ink

There is very little historical evidence concerning early printing inks. As no precise ink recipes have survived from printing’s experimental days, we have no way of determining the chemical composition of the inks used to print the incunabula with absolute certainty. Recently (2003-2004), analyses based on the most modern techniques have been conducted on original sheets of the Bible printed by Gutenberg in 1452, the famous 42-line Bible, the first complete book printed using letterpress techniques.

The results of these investigations, carried out by Bruno Fabbiani and Alessandro Gusmano, who formerly taught at the Politecnico di Torino, using IR and micro-Raman spectroscopy (with equipment provided Prof. M. Carnasciali of the Università di Genova Department of Chemistry), indicates that the ink employed by Gutenberg in the 42-line Bible contains linseed oil, walnut oil and lampblack. Walnut oil yellows more quickly than linseed oil but, if heated, dries more quickly: a determining factor for the amount of output a printer can achieve. A full report of these studies was given at the conference entitled “Printing from Mainz to Subiaco” held in Subiaco in September 2006, and in the published Proceedings of this conference.

Earlier, in 1985, Scientific American published an article by two University of California researchers, Richard Schwab and Thomas Cahill, who subjected the 42-line Bible – the B42 – to a nondestructive analysis technique they called Proton Milliprobe Analysis, which involved bombarding sheets of the B42 with a proton beam and then using a spectrometer to analyze the fluorescence spectra of the X-rays emitted. Their findings indicated that the ink prepared by Gutenberg contained lead and copper, as was shown by the spectrometric results.

This method of analysis was based on bombing a sample of the B42 with a proton beam accelerated by a cyclotron. The collision between protons and metallic elements contained in the sample causes the emission of X-rays and electrons, thus allowing to reveal the metals present in it through induced fluorescence, as metals are characterized by typical wavelength ranges. Copper and lead in the ink corresponded respectively to 55% and 36% of the total amount of calcium (to which a value of 100 was assigned) in the printed sample, with different values in different pages.

The actual percentage by weight of copper and lead salts falls far short of the amounts that are required as pigments in inks. The American research study, in fact, mentions lampblack as a pigment in the Gutenberg ink.

However, Cahill maintains that the variations in the copper/lead rate found in the pages of the B42 are due to the fact that Gutenberg’s workers, while using the same recipes, were quite wanton in adding to the ink copper and lead salts, whose chemical and physical functions cannot be explained.

As a matter of fact, the catalytic function of heavy metals in the oxy-polymerization of drying oils, i.e. the increase of their drying speed by adding, for example, cobalt and manganese salts (soaps) is a much more recent finding; moreover, to perform this function copper and lead salts must be soluble in the ink vehicle, consequently the addition of salts with this purpose in years as early as 1450 looks unlikely.

4.2 Composition of Gutenberg’s inks

The black copper and lead salts that were available in Gutenberg’s day for use as pigments are lead sulfide (PbS, a crystalline material occurring naturally as galena) and copper sulfide (occurring as various hard, crystalline cuprites with varying sulfur content), which could be found as such in Germany’s many mines.

It is not clear, however, why Gutenberg should have wanted to complicate his task by using costly substances that in their natural state occur as hard crystals, and thus require lengthy grinding in order to produce fine powders, which are not only very heavy but also yield a black that, though similar, is of lower quality than the economical and widely available lampblack and the black from oils.

Moreover, these metal powders’ high density means that they will precipitate even in drying oils that, like linseed oil, have been partially “boiled”, or in other words, heated to drive the water out of the oily extract of flax seeds and increase the oil’s viscosity.

Using the metal salts found by the two American researchers as pigments would thus be both useless and dangerous. Two other possible explanations for their presence can be put forward:

– The traces of metal detected in the analysis were in fact present in the ink, but came from the metal type or other portions of the formes used by Gutenberg, and were “incorporated” onto the paper as a result of the pressure exerted during printing; or

– The traces of metal derive from burning coal containing these metals to make lampblack, which, as the IR and micro-Raman analyses demonstrate, constituted the pigment in Gutenberg’s ink.

The fluorescence spectrometry method used by Schwab and Cahill, though excellent for detecting trace metals, cannot identify carbon (or other elements whose atomic weight is less than that of sodium). Consequently, lampblack, though a commonly used black pigment, can be neither detected nor measured by this technique.

The French historian Guy Bechtel, in his Gutenberg et l’invention de l’imprimerie, published by Librairie Arthème Fayard (1992), translated into Italian and published by SEI in 1995, takes up Schwab’s analyses and presents them with additions of his own, doing so with glaring errors that reveal his ignorance of chemistry.

The analysis shows that the minimum quantities for the elements found on the bare paper of the B42 (sodium, silica, chlorine, potassium, calcium, manganese, iron) are present in identical quantities on the inked portions of the paper; here, however, sulfur, copper, lead and traces of titanium also appear, apparently from the ink.

It is very likely that these minerals – sulfur, copper, lead and titanium – were part of the composition of, and were thus contributed by, the coals in Gutenberg’s area that were burnt to produce soot and lampblack, or for heating. Even in the not-too-distant past, the ashman would go from house to house collecting soot, and chimneysweeps would sell it to makers of ink and shoe polish.

On page 459 of the French edition, he states that “the color achieved is always the same despite the variations in the formula of the ink [by which he means differences in the relative proportions of the heavy metals found in the analysis] which occur from one page to the next”.

Aside from the fact that these variations would have virtually no influence on the optical density of the printed ink (and here we have a demonstration that Bechtel believes these metals, and not the lampblack, to be the pigments), if the American investigators found variations in the ink mixture on different pages, but the color of the printing does not change, it is obvious that this color does not depend on the metals, but on something else. That something is the lampblack, whose “black intensity” (scientifically measurable as optical density) varies according to combustion conditions, purity and the fineness attained in the micro-grinding process. In addition (and this is a fundamental fact), lampblack is extremely light: as a result, it forms stable dispersion without precipitating in oily vehicles, which can thus be applied evenly to metal type surfaces.

On the same page of this volume, Bechtel states that “on certain days, significant variations in the percentage of copper versus lead can be seen [in the B42], a fact we find inexplicable”. The fact, however, can be explained with no difficulty whosoever, because the composition of lampblack varies according to the type of coal that was burnt. This in turn affects the composition of the ink, which had to be prepared every day, or nearly every day, since it hardens rapidly if left in the open air because linseed oil and the other drying oils employed are readily oxidized and polymerized.

Consequently, the relative proportions of copper and lead would have varied if the daily batches of ink were prepared from lampblack made with coals from different areas, containing different percentages of these metals.

Conversely, if the lampblack is made with coal from the same source, the relative proportions of copper and lead will be the same in each batch of ink, regardless of the day it was prepared.

If, then, Bechtel is correct in saying that 294 production sequences with different batches of ink (i.e., having different proportions of copper and lead, proportions that Bechtel fails to specify) can be identified in the B42, this simply means that the different types of lampblack and soot at the printshop were mixed together, not that imprecise additions of metal salts to a pre-determined recipe were made.

Pure or purified metallic salts were, and still are, far more expensive than lampblack. In addition, it is improbable that sufficient quantities could have been obtained in a period when chemistry was still alchemy; therefore, they could not have been added.

The amount of lampblack needed to produce a good black is quite modest: around 3 to 5%, as lampblack is extremely light in weight.

The abovementioned metals are also found in Gutenberg’s 36-line Bible, i.e. the B36, but not in the same quantities; this elements supports my theory, as in that case lampblack was obtained from other coals.

The Cahill team has used the same method to analyze the 36-line Bible and the fragment known as the Sibyllenbuch which is kept in the Gutenberg Museum; here, too, considerable quantities of copper and lead have been detected, which therefore has been regarded as “Gutenberg’s signature”; my opinion, however, is that these are accidental facts, due to the composition of the fuels from which the lampblack was obtained.

Rather than by adding metal salts, the ink mixture’s drying behavior could have been easily altered by adding small and variable amounts of walnut oil to the main linseed oil, as the two oils have different drying behaviors. As an alternative, it would be possible to adjust the linseed oil’s viscosity to reflect the temperature, heating it for longer periods in hot weather and shorter periods in cold weather.

Unfortunately, the incursions of non-specialists, the rarity of Gutenberg’s surviving output, the lack of cooperation shown (often for chauvinistic reasons) by museums and of serious scientific analyses with modern instruments which lasted, with very few exceptions, throughout the twentieth century have caused continued uncertainty about the genesis of the B42 and the invention of printing types.

5. Renaissance, seventeenth century and eighteenth century inks

Printing flourished in the sixteenth century. Thanks to the elegance of the typefaces available at the time, and the excellent paper – made from cotton rags – then in general use, the output of that century stands as a brilliant synthesis of artistry and technique.

In the seventeenth century, faced with growing demand for printed books in a Europe ravaged by war and pestilence, printers were forced to sacrifice quality to cope with the rising costs of raw materials. As a result, the editions of this period are often remarkable only for their poor ink and poor paper.

A seventeenth century Dutch method for preparing the varnishes used in printing inks, described by Joseph Moxon of London (1627-1700), celebrated experimenter and author of Mechanick Exercises on the Whole Art of Printing, called for a good linseed oil. After the oil was heated, an onion was dropped into it to gauge the oil’s temperature on the basis of how quickly the onion cooked. Rosin (also known as Greek pitch), dried pine resin ground to powder in a mortar, was then added, and the oil was put back over the fire to dissolve the rosin and boil down the mixture to produce a homogenous varnish. At that point, one once of litharge (lead oxide) was added for every four gallons of ink to remove the tarry sludge that had formed in the mixture: the heavy oxide binds and precipitates the tarry residues. The mixture was then boiled again over a slow fire, allowed to cool, and filtered, after which it was set aside to rest as long as possible before adding the pigments needed to make ink.

According to a recipe by the French printer Martin-Dominique Fertel (1684-1752), on the other hand, walnut or linseed oil was boiled for two hours, adding bread crusts to remove the grease: in other words, the bread was used to absorb the tarry sludge and the excess oil that did not combine with the varnish.

Once charred, the bread crusts were removed andthe oil was boiled over a slow fire for another three hours. Since a “weaker”, i.e., less viscous, oil was needed in the winter because of the lower temperatures in the printshop (radiators, obviously, were far in the future), Fertel recommends adding an egg (an egg!) at the end. He also says that using turpentine, because of its rapid evaporation, prevents halos from forming around the printed letters, but that overusing it can make the ink dry too fast, causing the work to stick to the type, and thus tearing the paper when the print is pulled.

Consequently, turpentine was to be added to the oil only in a proportion of one to ten. Preparing the turpentine entailed another two hours of boiling, and the turpentine was added to the oil while they were both still hot; the mixture, then, was boiled for another quarter of an hour. Making a good product thus took a long time – and involved serious fire hazards!

Printing’s fortunes revived in the eighteenth century, and ink factories sprang up just about everywhere, particularly in England, France and Germany, though all trace of these small ink-making operations has since been lost. The first in order of time, according to the authoritative Annals of printing by W. Turner Berry and H.E. Poole (London, 1966), was a company set up in King Street, London, by William Blackwell (a surname that, for an inkmaker, says it all), in 1754.

Other sources assign precedence elsewhere, but in the absence of reliable documentation, we must accept Blackwell as Europe’s first ink factory.

The chemistry of the Age of Enlightenment came to the inkmakers’ aid with a number of publications – the Encyclopedie by Diderot and d’Alambert first and foremost – that illustrated combustion, distillation, mixing and all of the other techniques required to produce pigments and vehicles in explanatory images.

Lampblack continued to be prepared as it had been for centuries, using that classic tool of ancient chemistry, the copper retort(which takes its name from its shape, retorta in Medieval Latin meaning “bent back”) filled with oils, pitch, tar or coal. Heated, these materials would be broken down and distilled to produce carbon-rich fumes, which are burned under a large metal hood on which the coarser lampblack is deposited. The finer carbons is carried by the rising air through a hole in the hood, ending in a cold chamber on whose walls it is deposited.

An eighteenth century recipe states that the lampblack is blended along with other carbon-laden powders in “boiled” linseed oil, or in other words linseed oil that has been bodied by heating to drive the water out of the flax seed extract and thicken the oil into various degrees of viscosity, depending on the season, the temperature of the work area, and the type of material to be printed.

To eliminate the oily tars that accompany the lampblack, the mixture was heated in copper cauldrons until fumes arose that burned for a few moments: thus was the so-called “flame varnish” produced. The cauldron was then covered to put out the flames. The very viscous ink that this process yielded, penetrated very slightly into the paper and dried more quickly; to increase its viscosity even further, the makers added rosin to the cauldron.

Even in the eighteenth century, colored inks were rarely used (and in the heroic period of letterpress printing were almost unknown); an anonymous manuscript of 1706 refers to only five colors, prepared by mixing powdered minerals with linseed oil: red, orange, green, sienna and blue. Normally, however, makers limited themselves to producing a bit of red for ecclesiastical books (called “black-and-reds” in the trade because of the two colors of their inks). This red ink was made with linseed oil that had been bodied by heating (which eliminates water and causes oxy-polymerization of the oil molecules, thus forming macromolecules with crosslinked chains that become longer and longer as the oil thickens) to which finely ground mineral pigments of the desired color were added. Naturally, the color of these inks varied according to the source, purity and batch of the minerals used, while the latters’ scarcity also made them much more expensive than black ink.

A certain air of alchemy continued to surround ink-making for much of the seventeenth and eighteenth centuries, as exemplified by an anonymous recipe for oily red ink found by the author in a seventeenth century manuscript.

Walnut oil is boiled to thicken it, adding the heavy and enormously expensive ground cinnabar (reddish orange mercury sulfide) grain by grain. A few cloves of mashed garlic are then added (perhaps for the sulfur compounds it contains), and the oil is evaporated until it is reduced to one third of its original volume, yielding a viscous, stable product capable of holding the heavy cinnabar in suspension. Nevertheless, I am convinced that the pigment would eventually settle to the bottom of the container, but the alert craftsman would be quick to solve the problem with the simple method of shaking before use. Such homely methods are often the best, and in those days were likely to be the only ones available.

One of the major sources of information about eighteenth century inks is William Lewis’s Commercium philosophico-technicum(Oxford, 1763), which can be regarded as the first scientific investigation of iron gall inks and their preparation.

Adding sugar to iron gall inks, as was done by the inventor and engineer James Watt (1736 -1819), famous for his work with the steam engine, had long been known as a way of improving gloss. Sugar (like honey, dextrin, dextrose and gum arabic) ensures that ink adheres better to the paper and dries more slowly; as a result, adding sugar to ink makes it possible to make a “contact copy” of a document simply by pressing another sheet of paper to it within twenty-four hours of the time it was written. This is the principle behind the “letter copying machine” for which Watt and his partner Matthew Boulton (1728-1809) were issued a patent in 1780.

A formulation of this kind was used in a red ink – bookbinders’ red – made from chips of red Brazilian logwood (Heamatoxylum campechianum, once known as the Campeachy tree) left to steep in vinegar for three days, after which the infusion was boiled and filtered. Gum arabic and equal quantities of alum and sugar were added to the extract to give it body and improve the ink’s adhesion (the alum, aluminum sulfate, acts as a mordant) to the paper.

Interesting formulations have also come from anonymous compilations of recipes, now in private hands and jealously guarded by their owners, that often come to light by mere chance. The following example is an eighteenth century Piedmontese recipe, found by myself, for a color imitating gold.

Take gum arabic, twelve grossi (a unit of weight), and melt it; add one ounce of raw (metallic) mercury and two ounces of ammonium salt (ammonium sulfate). Place the whole in a glass vial sealed in the flame and heat it in an olla (an earthenware pot) full of ashes until the salt melts. Then add orpiment (red-orange arsenic trisulfide) and brass filings (brass being an alloy of copper and zinc), heating and mixing until the mercury amalgamates with the rest (the vial, we assume, is open, as otherwise it would explode). The result of this procedure, it seems to me, comes nowhere near to resembling gold, but is certain to poison its maker without undue delay.

Towards the middle of the eighteenth century, dyes began to be added to iron gall ink to strengthen its color and make it easier to write with.

Somewhat later (1763), Lewis investigated the extraction of natural vegetable dyes that would be soluble in the varnishes, vehicles and binders used in inks.

He advocated the use of an extract of a tropical American tree, logwood, (Haematoxylum campechianum L., 1753), a raw material that was to have major importance in later years. Logwood extract provides a group of reddish dyes that give a purplish tinge to inks.

Lewis’s work was followed by the research of the renowned chemist Charles W. Scheele (1742-1786), who addressed the same problems. In this period (and more especially in the subsequent century), increases in metallurgical and mechanical knowledge were applied to the construction of printing presse.

At this point, we will turn to thework of another of printing’s pioneers, Alois Senefelder, inventor of lithography (1798) and, above all, of a revolutionary material: lithographic ink.

6. Lithographic ink

There are remarkable parallels between the lives of Aloys Senefelder (1771-1834), to whom we owe lithography, and Johann Gensfleisch, better known as Gutenberg.

If Gutenberg famously pronounced his invention to be “adventure and art”, the same can be said of the sequence of discoveries and inventions credited to Senefelder.

As is often the lot of innovators, the adventure ended in failure for both, though Gutenberg had a harder fate on the whole; the art, on the other hand, manifested itself in both cases through a new power of expression that made printing an inexhaustible medium of communication.

Born in Prague on November 6, 1771, Aloys Senefelder was educated in Munich, which he left to study law in Ingolstadt. After his father’s death, he abandoned his studies and devoted himself to writing for the stage. Unable to have his plays published, he decided to print them himself, and thus started to experiment with copperplate etching.

To practice the reverse writing – writing backwards – that the etching process requires without wasting expensive copper plates, Senefelder hit on the idea of using the stone slabs from the Kehlheim quarries used to pave the streets of Munich as a substitute.

In the copperplate etching technique, the text or drawing to be printed is traced in reverse, as a mirror image, on a copper plate coated with a ground of acid-resistant wax or asphalt varnish. These traced lines cut through the ground, exposing the metal underneath. An acid solution is then applied which “bites” into the exposed metal, but not into the areas protected by the ground, leaving lines sunk into the plate. The plate is then inked and wiped off so that the ink remains only in the etched lines. When the print is made, a positive impression of the reverse image that was traced on the plate will be transferred to the paper: hence the need to write backwards on the plate to produce a legible print.

The story has it that, one morning in July 1796, Senefelder had to write a laundry list. The laundress (Figure 35) was waiting, but he could find no paper, so he used a stone he had polished in order to practice reverse writing, and a greasy ink consisting of beeswax, soap and lampblack that he had made to cover errors he had made in writing so that they would not be etched into the copper plate. Made at low heat, this mixture can be formed into sticks – or lithographic crayons – which can be inserted into a holder and used like an ordinary (though rather large) pencil.

Afterwards, Senefelder was curious to see what would happen if this stone were etched with aqua fortis (dilute nitric acid) for five minutes. He did so, and found that the areas that had been covered with the greasy ink were left in a slight though perceptible relief. He inked them, and was able to pull a print from the stone.

He continued to experiment, and found that when the stone was dampened with an acidic solution containing gum arabic, it became markedly hydrophilic, or in other words absorbed water readily (thanks to the intrinsic porosity of the type of stone used), but would no longer accept ordinary printing ink. The greasy ink he had invented, on the other hand, was repelled by the wet areas, and would adhere to the parts of the stone that had already been inked to produce the drawing.

The chemical explanation for this lies in the fact that greases are nonpolar dielectric materials with little affinity for polar liquids (i.e., whose molecules possess an electric dipole) such as aqueous solutions. This is why an oil or a grease will not mix with water.

Senefelder’s ink can be made almost liquid, and thus brushable, by changing its composition to include a wax solvent such as turpentine. Consequently, the lithographic method is capable of reproducing both drawings – executed with the lithographic crayon – and paintings executed with a brush and this modified liquid formulation, called tusche. Because of this versatility, lithography had enormous appeal for artists, and lithographic prints, either original (i.e., drawn directly on the stone by the artist) or reproductions of existing works, were produced in large numbers.

After drawing or writing with the greasy ink, Senefelder wet the stone with highly dilute nitric acid containing gum arabic to make the non-printing areas more hydrophilic. He then inked the stone with his greasy ink and printed (Figures 50, 51, 52, 53, 54, 55, 56, 57).

Senefelder gradually arrived at true lithography, based on the “chemical separation” between printing and non-printing areas, relying, not on relief as was the case for letterpress printing, but on the different chemical affinity that ink and water show for the image and the bare areas of the stone, separating the image from the stone by means of the chemical antagonism between acidulated water and oily ink.

Alternating wetting, inking and printing, Senefelder achieved an acceptable product in 1798: this was the discovery of a new printing method, which he called “chemical printing” in the account of his work that he published, much after the fact, in 1818.

The inventor also declared that he could produce 6000 impressions a day with three presses, which demonstrates that he had also solved the technical problems involved in making lithographic prints.

Of the many recipes for lithographic ink, I will give two, one from a well-known source, and one anonymous:

According to the great nineteenth century lithographer Lemercier (owner of the largest lithographic printing business in Paris) ink should by made of 4 parts of yellow wax, 3 parts of tallow, 13 parts of white Marseilles soap, 6 of shellac, and 3 of lampblack.
An anonymous late nineteenth century Piedmonteserecipe calls for: yellow wax, 400 g; tallow, 300 g: shellac, 500 g; gum mastic in drops, 100 g: purified white soap, 400 g: Veniceturpentine, 50 g: olive oil, 50 g; lampblack 100 g
And here is how to proceed for the anonymous recipe.

Melt the tallow in the hot oil, adding the lampblack bit by bit until the mixture is uniform and the consistency of a very thick cream which can be pressed into a block, as if it were butter.

Separately, melt the wax, half of the soap, and the shellac. At this point, the author, worried that an accident might happen, warns that:

“…you should take the material off the stove before it catches fire …the flames will rise higher and higher and you will have to be careful …to dominate them.”

The materials must be mixed in slowly “…throwing in small pinches, waiting until each melts before adding the next …”

When everything is liquefied, put out the fire and add the rest of the soap, a little at a time. Add the turpentine after the mixture has cooled (to avoid causing a fire) and then mix thoroughly over low heat. Filter to remove tarry residues. At this point, add the block of tallow and lampblack prepared earlier and place over moderate heat, stirring constantly until the mixture is completely melted and uniform. Then pour the ink onto a stone slab greased with tallow, allowing it to cool and harden sufficiently to be cut into tablets for sale or “cast” in brass molds to make lithographic crayons.

G.I. Arneudo, in his Dizionario esegetico, tecnico-storico per le arti grafiche, a dictionary of the graphic arts published in Torino in 1917, states that lithographers use three different types of ink: the “fine”, higher quality grade for crayon work, a medium quality grade for printing images based on pen and brush work, and a less viscous, lighter grade of ink for printing with fast and more or less automated presses where there would be a risk of tearing the sheets of paper.

Arneudo also says that the lithographic inks used in the late nineteenth century employed varying proportions (depending on the use for which they were intended) of soap, mastic in drops, yellow shellac, virgin wax, saltpeter and lampblack that had been purified to remove salts, resins and oily components.

Senefelder’s lithographic method, inks and press remained unchanged until the introduction of offset lithography in 1905; even today, lithography as an artistic medium still uses the same “stone-printing” techniques developed originally by Senefelder. Major changes, on the other hand, have been made for the inks now used in offset printing.

7. Advances in chemistry

In the nineteenth century, advances in chemistry opened up new horizons for ink making. In 1820 Reid, following in the footsteps of Bostok, found that fermentation of tannic acid by a mold produced pure gallic acid, which combined with ferric sulfate yielded an intense black color. After this, attempts were made to eliminate iron salts from ink-making processes, as their oxidation damaged manuscripts.

The famous Swedish chemist Jöns Jacob Berzelius (1779–1848) substituted iron salts with ammonium vanadate (1832), which reacts with gall to produce an indelible black liquid. This liquid, however, was found to fade when exposed to light for prolonged periods.

The first true vegetable dye used in inks was natural indigo (extracted from indigofera tinctoria), followed by indigo treated with sulfuric acid and other chemicals to make it more soluble. Potassium chromate began to be added from 1848 onwards: inks of this kind were reddish or purplish when applied, and turned black afterwards.

Other advances were made by Runge (1847), who can be considered the father of modern writing inks. He treated logwood with potassium chromate, obtaining a black ink with neutral pH.

The so-called “alizarine ink” which was to be so successful in the nineteenth century was invented by Eduard Leonhardi (1826-1905), whose patent dates to 1856. Alizarin is a red dye that had been extracted from the madder root since ancient times, and was then reproduced synthetically starting in 1858. Until then, the iron salts used in making inks were held in suspension by the thickening action of gum arabic. Leonhardi introduced a new formula in which the reaction with the iron salt did not take place in the liquid, but on the paper, as a result of the oxidizing action of the air on the salts, which do not react with alizarin. Consequently, there was no longer a risk that the salts would settle to the bottom of the inkwell. Instead of being black, this ink was thus the orangish color of the alizarin dye. On the paper, it would slowly darken as the ferrous salts oxidized into ferric iron, which with alizarin yields a rich, glossy black.

Prussian blue, also called Berlin blue or Paris blue, a synthetic dark blue pigment, was discovered by accident in Berlin by Diesbach and Dippel in 1704, though it began to be used in ink production only towards the middle of the nineteenth century. Chemically, it is ferric ferrocyanide, Fe4[Fe(CN)6]3.

Many attempts to produce dye-based inks were made, especially in the nineteenth century, but the real breakthrough came in 1856, when William Henry Perkin, attempting to synthesize quinine, happened across mauve, a violet dye derived from aniline.

The appearance of aniline colors around 1860 revolutionized the world of dyes, making it possible to produce writing inks based on pure dyes which neither clog the pen nor corrode paper.

For black inks, aniline dyes such as induline, methyl violet and nigrosine were used. For reds, common synthetic dyes include rhodamine and eosin.

What followed is the history of the modern ink industry, a subject we will return to later.

The new dyes opened the way to many new kinds of “sympathetic” or “invisible” ink, consisting of substances that change color when mixed with an acid or base (phenolphthalein, for example, which goes from colorless to purple when exposed to ammonia); many others rely on a full-scale chemical reaction that yield colored salts from colorless writing fluids (the classic example is cobalt chloride, nearly colorless, which turns blue with potassium ferricyanide).

7.1 Nineteenth century ink-making

The equipment required for ink-making is neither costly nor complicated to operate; essentially, the only things needed are containers for mixing the solid and liquid raw materials, a few filters, and more containers where the ink can be left to age and settle.

The containers used were wooden vats, or even ordinary barrels, when the solid and liquid raw materials were mixed into solution without heating. If heating was needed, cylindrical metal boilers with a slightly concave bottom were used instead of vats. These boilers were made of heavy gauge iron sheet, and could be chromium plated to improve their resistance to corrosive chemical reagents, or enameled if the solutions to be heated contained substances that could be affected by contact with metals.

In certain cases, however, materials could also be heated directly in the wooden vats by connecting a steam generator to them.

Nineteenth century boilers and vats already featured a manual or mechanical stirrer to mix and dissolve the solid raw materials in the liquid solution.

Where small quantities of liquid had to be filtered, ordinary cloth or paper filters placed in large funnels were sufficient. For larger volumes, filter presses were already in use by the end of the century. These units consist of a series of removable wooden or metal frames, each carrying a sheet of high-grade filter paper or cotton canvas. A pump forces the cloudy liquid through each of the frames, which retain the solid matter, and the filtered liquid is collected in a channel below the press.

Care was taken to ensure that the water used for nineteenth century writing inks did not contain salts of iron, manganese, calcium or magnesium: compounds of iron and manganese can cloud certain aniline dyes, while calcium and magnesium salts cause tannin, and many dyes, to precipitate out of solution. Natural waters, however, invariably contain mineral salts, especially those of calcium and magnesium.

Hard waters are far more abundant in nature than soft waters. Before they are used, these waters must thus be softened by means of a treatment that removes most of the calcium and magnesium salts.

Inks are rarely ready for use immediately after they are made; they acquire the desired properties only after a certain period of rest, away from contact with the air, in which a number of complex phenomena occur in a process of “maturing”. Good black writing inks were left to rest for six to twelve months.

In 1818, ink-making was put on an industrial basis when Pierre Lorilleux, printer at the Imprimerie Royale, founded an ink factory in Paris. Success came quickly, and to meet the flood of orders he received, Lorilleux was soon obliged to add to the capacity of his first primitive workshop on the banks of the Bièvre at Meison Blanche (1820) by building a second, and far larger, factory on the hill at Puteaux (1824)

In 1823, Savage published a book dealing with all the major methods for making black and colored printing inks, while in 1848, H.D. Wade, a New York druggist, was the first to experiment with mixtures of resins as a partial substitute for linseed oil.

In the meantime, sophisticated metal printing presses appeared on the market (Figure 58), fruit of the period’s improvements in machining techniques.

1816, Angelo Belluschi, a former pressman, set up a small printing ink plant in Via Moscova 37, Milan. Two years later, he hired Camillo Orsenigo, who became a partner in 1829 and owner of the plant in 1850.

In 1857, Camillo’s son Francesco Orsenigo introduced the first three-roll ink mill – a heavy machine with three granite rolls that replaced the mortals and pestles previously used to grind inks. The Orsenigo factory enjoyed considerable fame, not least because it was the only Italian plant to patent its inks. It was equipped with twenty steam-driven machines for making letterpress and lithographic inks. The company also made inks for newspapers printed on reel-fed rotary presses: revolutionary for their day. Prices ranged from 1 to 2 Lire per kilogram, depending on color. Also highly successful – and, at 20 Lire, highly priced, was theTavolozza tipografica (The Printer’s Palette) published by Orsenigo.

In Torino, the first ink factory was founded by Francesco Berra, ex-pressman at the Stamperia Reale. In 1829, Berra displayed several examples of colored and black and white prints made with his own inks at the city’s Public Exposition. His work won a medal, though only a bronze one.

In 1831, the “Fratelli Berra” factory applied for a license that would give them exclusive rights to produce inks “by appointment” in the Royal States of Savoy, but the Consiglio di Commercio – the kingdom’s board of trade – refused on the grounds that an ink factory already existed …in Genoa! Not exactly next door, perhaps, but how many ink-makers could a self-respecting little state possibly need? Undaunted by this denial, the company continued production, and contributed to freeing Piedmont from its dependence on imported French inks.

By the end of the nineteenth century, the chemical industry produced thousands of kinds of pigments and dyes, and ink-makers had only to choose the ones that would be best for each particular need. To entice prospective customers, ink producers arrayed their wares in chromolithographed labels showing Oriental landscapes and exotic odalisques in entire rainbows of alluring color, which even today have lost none of their appeal.

Then as now, pigments were chosen for their hue, saturation, purity, lightfastness, and insolubility in water and oils (Fig. 59,60,61,62,63,64,66,67,69,70,71,72,79,83).

Other properties depend on the varnishes and vehicles used, and include their ability to ensure that the ink has the right consistency (the right amount of body and tack), can produce a good, glossy print, and has sufficient abrasion resistance.

7.2 A brief digression on metal pens and nibs

Metal pens have also had an importance of their own in the development of writing and the history of ink. Metal pens have very early origins, though the exact date of their invention is not known. Naturally enough, the encyclopedia Larousse, practically a French national institution, patriotically states that the metal nib was invented in the second half of the eighteenth century by a French mechanic, one J. Arnoux. In the English-speaking world, the magazine Cosmos, in its issue of September 15, 1900, assigns credit for the invention to the American Peregrine Williamson, a jeweler, around 1800. The Germans also claim paternity of this tiny but nonetheless important instrument, attributing it to a schoolteacher in Koenigsberg named Burger, who published an account of his new contribution in 1808. But the Englishman James Perry came to hear of the invention, and took out a patent for it in 1830. As compulsory education spread throughout Europe and beyond, millions of Perry’s steel nibs were sold around the world, and he quickly became a millionaire.

The metal pen, with its replaceable nib slipped into a holder, completely superseded other writing implements because of its inherent advantages The nib is flexible and long-lasting, and can be made in different shapes and styles to imitate ancient forms of calligraphy or invent new ones. Steel nibs were the most economical, though they tend to rust. This is a problem that nickel-plated nibs (the humble nickel looks like gold) do not have, while bronze or chromium-plated and stainless steel nibs were also in considerable demand, thought their prices are obviously higher. British brands were among the most important, and were widely available even in Italy: our grandparents could name such famous nib makers as James Perry, John Mitchell, and Hinks Wells & Co. Well-known French products included those by Blanzy-Poure, Baignol & Fairon, Mallat, and Conté, while the Germans could boast Heinze & Blankertz of Berlin, Brause & C., and Soennecke of Bonn (Figures 65,68,73,75,80,81,82,84,86,88).

In the Italy of the 1920s, prominent metal pen makers included Presbitero, Legnani, Ruspi, Locati and Fiore. Each producer had a series of exclusive models, each identified by its own trademark. Ruspi, for example, offered the Astoria, Cobaltea, Elettra, Trionfo, and Sahara lines, while Legnani models included the Freccia d’oro, Gloria, Littorina, Serpentina, Impero and Lux, names redolent of the Fascist period. Some of these pens are amusing because of their odd shape: the “penna reale”, for instance, impressed with a royal crown, or the “penna antonelliana”, modeled after Torino’s Mole Antonelliana, symbol of the city and most prominent feature of its skyline.

Many other makers served the large market for metal nibs. And then came the 1950s and the unstoppable rise of the ballpoint pen: unstoppable despite its early ban from elementary schools, where fledgling penmen were still required to leant to “write in ink”.

7.3 New writing implements

A pen that would not have to be dipped continually in the inkwell is a very old idea. The first historical record of a pen carrying its own supply of ink dates back to the tenth century. We are told that in 953 AD, the caliph of Egypt demanded a pen that would not stain his hands or clothes, and was provided with a pen which held ink in a reservoir and delivered it to the nib via gravity. Obviously enough, this is all we know of this pen.

Documented attempts to construct a reservoir pen are far more recent: drawings by Leonardo da Vinci show a pen with an ink chamber that has been reconstructed in modern times on the basis of these few sketches. Some scholars maintain that careful analysis of the writing in Leonardo’s codexes shows it to have a regularity and continuity that could not have been achieved if the pen had had to be dipped in the ink every few moments; the same is true, they say, of the many ink drawings that illustrate the codexes. It is thus not too far-fetched to conclude that Leonardo did in fact make a reservoir pen, and used it in his work.

In his Delicia Physic-Mathematicae, the German mathematician, inventor, poet and librarian Daniel Schwenter (1585-1636) describes a pen made from two goose quills, where one quill served as a reservoir for ink inside the other quill. The ink was sealed inside the quill with a cork, and was squeezed through a small hole to the writing point.

Pens of this kind were produced in the seventeenth century, but none survive. Progress in developing a reliable pen was slow, however, until the mid-nineteenth century, largely because of the very imperfect understanding of the role played by air pressure in the operation of reservoir pens, and the fact that inks were still highly corrosive and full of sedimentary inclusions.

The modern history of the fountain pen began in 1780, when a certain Scheller made a bronze and horn prototype of which little is known; it was not until 1827 that the French government issued a patent for a reservoir pen invented by a young Romanian, Petrache Poenaru (1799-1875), physicist, engineer and designer of Romania’s current tricolor flag, who was then studying in Paris.

Starting in 1850, there was a constant increase in fountain pen patents and the number of pens in production. It was only after three key inventions, however, that the fountain pen became a widely popular writing instrument: the iridium-tipped gold nib, free-flowing ink, and the hard moldable rubber, or ebonite, used for the pen barrel and developed by Charles Goodyear and Thomas Hancock in 1843 through the prolonged vulcanization of a mixture of natural rubber and sulfur.

In 1870, Duncan MacKinnon, a Canadian, made a stylographic pen with a hollow, tubular nib and a wire acting as a valve: a technique adopted for the pens employing India ink which were long used for drafting and technical drawing. Mass production of these writing instruments began towards the end of the century, when they became a popular status symbol.

In this period, fountain pens were filled by unscrewing a portion of the hollow barrel or holder and inserting the ink by means of an eyedropper. This was a slow and messy system. Fountain pens also tended to leak inside the caps and at the joint where the barrel opened for filling. The problem to be solved was that of creating a simple, convenient self-filler that would not leak.

The modern fountain pen contains a reservoir of liquid ink which is supplied precisely and constantly to the nib by means of a feed system which operates through a combination of gravity and capillary action. Ink can be delivered to the nib from pre-filled cartridges or a mechanism similar to an eyedropper, or by using any of a variety of ingenious systems. Most fountain pens use disposable ink cartridges or a reservoir filled with a screw or piston mechanism (Figures 95, 96).

For the more costly models (an expensive fountain pen is always a status symbol), chrome steel nibs are replaced by wear-resistant iridium tipped gold or even platinum nibs. Fountain pens, once among the most common of writing instruments, have been produced in innumerable designs, ranging from the starkly ergonomic to the lavishly luxurious.

A number of formulas for fountain pen inks (as indicated by the 1965 edition of the classic Italian chemistry reference, the “Nuovissimo ricettario chimico”) contain varying percentages of glycerin, ethylene glycol and distilled water in addition to dyes such as methyl violet, nigrosine and so forth. There have been no important changes in this area in recent years, as the advent of new writing implements such as ballpoint, rollerball and felt-tip pens has caused consumption to drop sharply. Nevertheless, bottles of fountain pen ink are still sold, and the elegant ink bottles of bygone days have, like bottles of vintage wines, become prized collectors’ items, proudly displayed in glittering showcases (Figures 90, 91, 92, 93, 94, 97, 98, 99).

7.4 The ballpoint pen: revolution of the spheres

The history of the ballpoint pen had a definite beginning, if we look only at documented patents. How and when the idea arose, however, is open to debate.

In 1888, John Loud, an American tanner, patented several types of marking pen featuring an ink reservoir and tip containing a small rotating ball that applied thick ink to leather hides. John Loud’s pen was never produced or used for writing on paper. A replacement had yet to be found for the fountain pen and its ink that tended to smear if the writer was too fast: a problem much decried by the movers and shakers of the bustling industrial age.

In 1891, a similar patent was filed by a certain Edward Lambert. The ballpoint pen we know today, called a biro in many parts of the world, owes this name to its real inventor, the Hungarian journalist László József Bíró (1889-1985). Birò first tried to eliminate the problem of smudging encountered with fountain pens by replacing the ink with the fast-drying type used to print his newspaper. Printing ink, though, was thick and hard to write with, since it would flow into the fountain pen’s nib barely, if at all. So Birò had another idea: fitting a tiny metal ball in a socket on the tip of the pen, which would thus distribute the ink more evenly on the paper. It is said that the idea came to Bíró from seeing a soccer ball roll through a puddle and leave a wet stripe on the asphalt.

Birò’s experiments were interrupted by history: the Second World War was looming on the horizon, and Birò, together with his family, fled first to Paris and then to Argentina. Here he began to produce his pen with the help of various experts: to operate correctly, it needed a metal ball with very precise dimensions that could only be supplied by a Swiss company. Another problem was that of developing an ink with the right viscosity: initially, this was an area where Birò was assisted by his brother, György. In 1935, Birò patented his pen in Hungary

In the same year, Frank Klimes and Paul Eisner were the first to put a ballpoint pen on the market: the Rolpen. In 1939, Biro tried to produce his pen in France, but was forced to stop because of the war. It was not until 1943 that he was able to patent his invention and, financed by Henry Martin, started to produce it in Argentina as the Stratopen. In 1945, the Italian baron and naturalized French citizen Marcel Bich (Torino 1914 –Paris 1994) bought the Birò brothers’ patent and began to manufacture pens in small batches, as he did not yet have the technology to improve the produce and make it mass-marketable.

Bich, born of a noble family from Italy’s Valle D’Aosta who had moved first to Torino and then to France, created an industry to which he gave his own surname, minus the final ‘h’: Société Bic. He perfected the ballpoint and sold it, in ever-increasing volumes, around the world: it was perhaps the first example of the disposable consumer goods that have become such a feature of modern life. Bich had two other ingenious ideas: the disposable razor and the disposable cigarette lighter. Today, and every day, millions of people around the world write, shave and light their cigarettes with Marcel Bich’s economical and extraordinarily practical inventions.

The first great commercial success for the ballpoint pen came in October 1945, when Milton Reynolds sold his pens at Gimbels Department Store in New York. A crowd of over 5000 people jammed the Manhattan store’s entrance: astutely, Gimbels had taken out a full-page ad in the New York Times the day before to promote the first sale of ballpoints in the United States. The ad described the new pen as a “fantastic…miraculous fountain pen… guaranteed to write for two years without refilling”. On that first day of sales, Gimbels sold out its entire stock of 10,000 pens – at the hefty price of $12.50 each.

Bich became enormously wealthy, while Birò died poor in Buenos Aires in 1985; Argentina, however, celebrates “Inventors’ Day” on Birò’s birthday, September 29.

The ballpoint pen consists of an internal chamber (or refill) filled with a viscous ink that is dispensed at the tip by the rolling action of a small metal sphere between 0.1 mm and 1 millimeter in diameter; the more economical pens have larger diameter spheres. The sphere may be steel of tungsten carbide, or even, on the more expensive models, sapphire. The chamber holds from 0.4 to 0.6 grams of extremely viscous ink, which in theory is enough for a line 15,000 to 16,000 meters long. The ink dries almost immediately after contact with paper (Figures 100, 101, 102).

Inexpensive, reliable and maintenance-free, the ballpoint has largely replaced the fountain pen.

Ballpoint pen ink must be thick enough not to run, or in other words leak past the metal tip and cause stains when the pen is set down somewhere or put in a pocket. It must write smoothly, but not migrate through the paper and be visible on the other side of the sheet. It must also stay at the right viscosity, even after the pen has been used for hours or when the temperature changes.

In addition, the ink acts as a lubricant for the metal ball. The coloring agents it contains are soluble in oil: alkaline dyes dispersed in fatty acids, acid dyes such as nigrosine – economical, but tending to break down under UV light – and the more lightfast phthalocyanines and methyl violet, as well as pigments or graphites dissolved or suspended in a sufficiently viscous vehicle.

The vehicle may be a high molecular weight alcohol, an ester, mixed with small amounts of natural or synthetic resins. Until around 1970, vehicles contained olein (oleic acid), though this is no longer used today because of its tendency to oxidize, polymerize and stop flowing. Currently, esters such as isostearate (glyceryl) or oleylsarcosinate, which do not oxidize and block the flow, are used together with glycols and polyglycols that are not subject to oxy-polymerization, and may be combined with stable synthetic resins.

An important innovation has recently been introduced: oil-based inks have been replaced by highly fluid gel inks which write very smoothly, much like a fountain pen. These inks have gained a large market: though fluid, they do not drip because of their carefully controlled use ofthixotropy. This thixotropy means that the ink becomes very viscous when the pen is not being used, but its viscosity drops abruptly when the pen starts writing. The phenomenon is caused by the change in velocity that the pen undergoes in writing, and is made possible by special “associative” polymers contained in the ink.

7.5 A new way of writing: fiber tip pens

Fiber or felt tip pens first came on the market over thirty years ago. They use low-viscosity ink that flows readily through the capillary network formed by the sintered (i.e., bonded together by partial melting) polyester fibers that form the pen’s tip. If their fluidity and drying properties are well balanced, the inks used in these pens write smoothly and produce clean, crisp lines in a variety of widths, depending on the size of the tip. These inks now consist of water-based solutions of dyes that are safe for children. Adding high boiling liquids such as ethylene glycol to the ink formulation prevents the tip from drying out, extending the pen’s life.

Permanent markers, on the other hand, use inks with an alcohol-based vehicle and can write on virtually any surface, making markings that cannot be washed off with water. Tip sizes vary from the ultra-fine microliners to the wide-tip markers used for signs and posters.

Inks general consist of acid or basic dyes in an alcohol base. More rarely, they may employ grease-soluble dyes in a base consisting of a nontoxic hydrocarbon. Both types contain a resin, which must be soluble in alcohol in the first case and in hydrocarbons in the second.

Highlighters, a more recent invention, are also widely used. They contain fluorescent dyes that do not photocopy well in normal copiers because of their high reflectance: they reflect the light beam moving across the paper in the machine, and thus show up on the copy as almost white.

Another type of fiber tip marker is the whiteboard marker or dry-erase marker used on the painted or plastic coated whiteboards that have replaced chalkboards in many schools. Whiteboard makers can be erased with a cloth, without creating the clouds of chalk dust that once hung so long in the classroom air.

8. New printing inks

To round off this brief history, we will also devote a little space to contemporary inks, though their variety and complexity deserve far more attention than can be devoted to them here.

In the late nineteenth century, the introduction of triple roller ink mills with granite – or even harder jasper – grinding rolls had made it possible to produce much finer pigment pastes. By the turn of the century, according to Arneudo, the finest and highest quality printing ink was ground ten or twelve times.

Once the hand press had been abandoned, flatbed cylinder presses were first supplied with sheets manually. Later, towards the end of the nineteenth century, they were equipped with mechanical automatic feeders that sped up production and made presses safer to work with. This, however, made it necessary to develop faster drying inks to prevent “set-off”, or in other words the transfer of ink from one sheet to another when they are stacked at the delivery end of the press.

Where a single formula had once been sufficient, many different types of printing ink were gradually developed for different impression techniques and different types of work, using, for instance, higher viscosity formulations for sheet-fed presses and lower viscosity inks for the faster web-fed machines.

Inefficient mineral pigments were abandoned in favor of synthetic pigments for colored inks. For example, inorganic mineral pigments have been replaced by organometallic pigments such as copper phthalocyanine, which have higher chromatic intensity, produce more uniform colors, are lighter in weight, and are compatible with a wide range of vehicles.

The major thrust of research and development work has shifted away from writing inks, to concentrate to a much greater degree on printing inks and the methods for producing them.

After 1930, new resins derived from polymers synthesized from petroleum products were used for varnishes and binders. Vehicles made with these novolac phenolic resins have more consistent properties than those produced from natural substances, which can vary significantly according to source and age.

Following the Second World War, synthetic resins made enormous steps forward, becoming the basis of all printing inks.

Even with all these changes, the history of ink is sometimes one of continuity. Armando Maloberti of the ink factory of the same name tells me that in the 1930s, the last descendent of the Orsenigo family, Camillo, was the driving force who enabled the well-known Paris ink producer Lorilleux-Le Franc to expand its Italian business. He made a fundamental contribution to setting up the Lorilleux facilities in Via Benigno Crespi, Milan, where the company remained until it relocated to Senago in the 1970s. Lorilleux continued its growth in Italy by absorbing Battistini’s equally well-known company, Cometa S.p.A. (Figures 74,76,77,78,85,87,89).

More recently, Lorilleux formed an alliance with the British maker Coates in the late ‘80s. The Coates Lorilleux partnership was then acquired by TotalFina, which also bought the Colorama group. At the end of the last century, Coates Lorilleux merged with Sun Chemicals, a wholly-owned subsidiary of Japan’s Dainippon.

8.1 High-viscosity inks

Inks with a highly viscous vehicle, known in the trade as “paste” inks, have been used from the beginnings of printing down to our own day. They are still extremely important, as they include letterpress inks, offset inks and gravure inks.

To give a brief description of how these materials work, we can say that the film-forming portion of the ink laid down on the paper, which consists of the various kinds of synthetic resin that make up the varnish, stratifies and solidifies instantaneously, “trapping” the pigments. The volatile components, on the other hand, are absorbed by the paper fibers and then released more slowly.

Letterpress and offset ink formulas differ in several respects: offset inks do not contain certain pigments that bleed as a result of the dampening used in offset printing, while their varnishes cannot contain components that tend to form oil and water emulsions.

Polychrome prints are produced using the three basic printing ink colors: yellow, magenta (a purplish red) and cyan (blue-green), which can be combined together to provide a full range of colors through “subtractive synthesis”.

Obviously, a modern ink is made up of many different ingredients. Once the pigments and dyes have been selected, and the resins for the varnish, it will be necessary to determine the relative proportions that will be needed to produce the desired color and the right amount of body (viscosity) for the printing method that will be used. A variety of dispersants, wetting agents, viscosity modifiers, plasticizers, driers, surfactants and biocides must them be added.

Because of their high speeds, modern presses require inks that retain a certain amount of body, but have less tack to prevent problems such as picking, i.e., lifting and pulling the paper surface, that could result in tearing with the cheaper and thinner stocks used today. Gelling agents and rheology modifiers are thus used, either as components of the ink or added at the time of printing.

Polydispersed varnishes are used to ensure that the ink dries quickly – almost instantaneously – on the paper stock. When these varnishes hit the paper, they separate into two parts, a fluid and a binder. The solvent-based fluid penetrates into the paper’s pores through capillary action, while the binder or film-forming portion of the ink, which consists of hard resins, quickly thickens to form a compact, but not entirely dry, layer. We thus have a form of “selective penetration” that causes the ink to set rapidly; drying will be completed in a few hours without ink set-off or blocking, i.e., the problem where the printed sheets stick together.

Fast web-fed offset presses use heatset inks: the freshly printed stock passes through a heating unit that emits infrared radiation which is absorbed by the varnishes and binders used in these inks, drying them by evaporation.

8.2 Low-viscosity or “liquid” inks

Like their paste counterparts, liquid inks also consist of resin and solvent vehicles containing pigments and dyes that produce the desired color. They include rotogravure inks, used in printing large runs of illustrated magazines and wrapping paper, and flexographic inks, used for newspapers, packaging, flexible plastics and metal foils. Both types share certain characteristics. The first and most important of these characteristics is that they must be based on volatile solvents so that they can dry by rapid evaporation. Consequently, the binders are liquids, though dense ones.

The solvents used in the two types of ink differ: xylene (an aromatic hydrocarbon derived from petroleum) and ethyl acetate for rotogravure inks; ethyl alcohol and water for flexographic inks. The non-aqueous solvents are recovered and recycled.

The properties required for the pigments used in liquid inks are essentially the same as for other inks: lightfastness, resistance to solvents, and resistance to oils and fats (the latter is particularly important for inks used on packaging materials in contact with foods).

Other important properties for pigments include fineness, softness and dispersability in vehicles. The most commonly used pigments for rotogravure inks are benzidine yellows and phthalocyanine blues. For blacks, the basic pigment is still lampblack.

For flexographic inks prepared with dyes dissolved in alcohol, a fixative such as synthetic tannin and/or lacquer is usually added to improve adhesion to the substrate or prevent bleeding if it gets wet.

For many decades, flexographic printing meant printing with aniline dyes: the process, in fact, was called aniline printing. The inks were often prepared at the time of use by the printers themselves. This was not necessarily complicated: for example, the printers could take 10 kilograms of ethyl alcohol and dissolve around 2 kilos of Victoria blue in it, shake vigorously, and they had their ink.

Hot air or infrared (IR) radiation are used to speed up drying and make sure it is complete. For the resins used in these inks, the main requirement is good solvent release, as otherwise the ink could not be used on fast machines. A thin coating of overprint varnish is often applied to the printed material after the ink has dried to protect it and improve appearance.

The utmost attention must be devoted to ensuring that the dried ink film is resistant to abrasion. Abrasion resistance depends on how well the pigment is coated by the binder, or in other words, the pigment’s wettability.

The ink’s runnability – or in other words, how well it interacts with the press and the substrate – and perfect pigment dispersion are key properties that ensure that the ink can be applied evenly and continuously. Another important consideration is the fact that solvents may be toxic, and must thus be recovered after evaporation and recycled rather than being released into the environment.

8.3 Screen printing and engraving inks

Screen printing and engraving are printing methods that are now largely restricted to the fine arts, where both are widely used, and to special applications: engraving is employed for banknotes, stock certificates and the like, while screen printing is used for premium packaging and to print on non-flat surfaces.

Screen printing inks and engraving inks dry by oxidation and polymerization, or in other words, slowly. Four to five hours after printing, they have set sufficiently to allow the prints to be handled. Complete drying takes two or three days. The varnishes for these traditional inks are made with drying oils (linseed oil, wood oils, etc.) and their derivatives (lithographic varnishes, glycerophtalic resins), plus phenolic resin binders and lead, cobalt or manganese driers.

Screen printing inks have recently been developed that dry by photopolymerization with brief exposure to ultraviolet (UV) light at a calibrated radiation wavelength. This has made it possible to increase the range of applications for screen printing, which has always been appreciated for the excellent colors and high quality it can produce.

The thickness of the ink layer deposited on the substrate with screen printing is approximately ten times greater than with offset printing: several hundredths of a millimeter, and in some particular cases – fine art reproductions, for example – it may be as much as one tenth of a millimeter.

Screen printing inks are used to print on a wide variety of materials: paper, cardboard, wood, leather, cloth, metals and rigid and flexible plastics.

Other so-called “synthetic” screen printing inks are available which are based on vinyl or cellulose base binders dissolved in solvents. These inks dry by rapid evaporation in only a few minutes.

Recently, inks based on hard epoxy resins have been developed which yield prints with high surface gloss and mechanical strength.

8.4 Specialty inks

There is an incredibly variety of inks that are used only for special or limited purposes and are thus not widely known, which we will mention here because of their intrinsic interest.

Luminescent inks, for instance, reflect light in a particular way. They derive their essential properties – fluorescence orphosphorescence – from the pigments they employ.

Fluorescent pigments make the print brighter because they also reflect the (invisible) ultraviolet components of the spectrum in visible light, an effect which ceases when the pigment is no longer excited by light. Phosphorescent pigments, on the other hand, continue to be luminescent, i.e., emit light, even after the exciting cause has been removed, because they return the light energy that was accumulated during exposure. The vehicle used for the pigment must be such that it does not interfere with this phenomenon. Phosphorescent pigments have a rather large crystalline grain size, and in practice can thus be used only in screen printing inks. By contrast, fluorescent organic pigments are fine, soft powders and can be used to produce writing inks (as used in fiber tip pens and highlighters) and in offset inks for printing brilliantly colored posters.

The panorama of inks in current use is so broad and complex that we can do little more than list them here.

There are moisture-set and steam-set inks, that dry and bind to the paper by precipitation when exposed to water or water vapor, two-tone inks, copy inks and security inks for checks and banknotes, liquid and powder toners for photocopiers, magnetic inks that can be recognized by electronic reading equipment, metallic inks in many different colors, as well as iridescent and pearlescent inks, liquid ink-jet inks for fast printers, waxy sublimation inks for slower printing processes, scented inks, and so on, almost endlessly. Obviously, these inks are protected by patents, and the technological complexities involved in their formulations are difficult for the non-specialist to grasp (fig. 103,104,105).

Thus, the chemical composition of these mixtures and specific functions of their components are beyond our scope here, which is essentially to provide a brief,though necessarily technological, history of ink.

ConclusionTo conclude this study, which has proved far more engrossing than I would have thought possible at the outset, I would like to quote a thought expressed by the Benedictine novice Adso in Umberto Eco’s The Name of the Rose, because it conveys the noblest function that ink can fulfil: passing on knowledge, and preserving it even in the most tragic moments of history.

“… for centuries and centuries men like these monks have
seen the barbarian hordes burst in, sack their abbeys,
plunge kingdoms into chasms of fire, and yet
they have gone on cherishing parchments and inks,
have continued to read, moving their lips over words
that have been handed down through centuries and
which they will hand down to the centuries to come.”

Chronological bibliography

Alessio Piemontese, De secretis libri septem, Basle, 1557
Giovan Battista della Porta, Magiae naturalis libri viginti, 1567
Schwenter, Daniel, Delicia Physic-Mathematicae, Nuremberg, 1636
Marci von Kronland, Johannes Marcus, De proportione motus figurarum rectilinearum et circuli quadratura ex motu, 1648
Otto Tachenius, Hippocrates Chimicus, 1666
Moxon, Joseph, Mechanick Exercises on the Whole Art of Printing, London, 1683-84
Caneparius, Petrus Maria, De Atramentis cujusque Generis, London. 1660
Diderot and d’Alambert, Encyclopédie ou Dictionnaire raisonné des sciences, des arts et des métiers, published from 1750 to 1770
Boyle, Robert, Some considerations touching the Usefulness of Experimental Natural Philosophy, Oxford, 1763
Lewis, William, Commercium philosophico-technicum, Oxford, 1763
Luckombe, Philip, The history and art of printing, London, J. Johnson, 1771
Hullmandell, Charles, Manual of lithography, London, 1832
Timperley, C.H. The printer’s manual, London, H. Johnson, 1838
Beckmann, History of Inventions, vol. I p106, vol. II p266, London, 1846
Figuier, Louis, Inventions anciennes et modernes, Paris, Hachette, 1865
Smith, William, A School Dictionary of Greek and Roman Antiquities, New York, 1873
Doyen, Camillo, Manuale di litografia, Hoepli, Milano,1895
Guarreschi, Icilio, Gli inchiostri da scrivere, Milano, 1915
Arneudo, Isidoro, Dizionario esegetico, tecnico-storico per le arti grafiche, vol. 3, Torino, 1917
Longo and Simonelli, Inchiostro, in Enciclopedia Italiana Treccani, vol. XVIII, 1933
Schedula diversarum artium by Theophilus Presbyter (XI-XII century) Theobold, Berlin, 1933
Davies, Hugh, Devices of the Early Printers 1457-1560, London, Grafton, 1935
Bargillat, Alain, Encres d’imprimerie et couleurs, in Enciclopedie francaise, vol. XVIII, Paris, 1940
Gallo, Alfonso, Il libro, Studium Urbis, Rome, 1942
Jennett, Sean, Pioneers of printing, London, Routledge, 1958
Febvre, Lucien, Martin, H.J., L’apparition du livre, Paris, Michel, 1958
C.H. Bloy, A history of printing inks, 1967
Berry, W. Turner, and Poole, H.E., Annals of printing, London, 1966
Italia, A. Pigmenti per inchiostri, Enciclopedia della stampa, SEI, Torino, 1968
Villa, A., Inchiostri e materiali per la stampa, Enciclopedia della stampa, SEI, Torino, 1968
Orsenigo, Camillo. Inchiostri da stampa, in Enciclopedia della stampa, SEI, Torino, 1968
Soave, Emilio, L’industria tipografica in Piemonte, Torino, Gribaudi, 1976
Vandier-Nicolas, Nicole. Art et sagesse en Chine, Presses Universitaires de France – PUF, 1985
Gusmano, Alessandro. Identificazione di stampe antiche e moderne, Milano, Arti Poligrafiche Europee, 1990
Bechtel, Guy. Gutenberg, Paris, Librairie Arthème Fayard, 1992
Gusmano, Alessandro. Due secoli di litografia, Milano, Arti Poligrafiche Europee, 1994
Benevello E., Gusmano A. Inchiostri per la stampa, in Grafica, vol.III, Arti Poligrafiche Europee, Milano,1995
Gusmano, Alessandro. Stampe d’arte e di pregio, Milano, Arti Poligrafiche Europee, 1999
A. Bartl, C. Krekel, M. Lautenschlager, D. Oltrogge. Liber illuministarum, Stuttgart, Steiner, 2005
Gusmano, Alessandro. Moderne analisi scientifiche sulla B42, Proceedings of the Subiaco Conference, 2006

Historical and bibliographical summary

The major historical treatises dealing with pigments, inks and the like are briefly described below.

Third to Fifth Century

Leyden Papyrus. The oldest extant manuscripts dealing with chemistry and alchemy date from the end of the third century. They are the celebrated Leyden papyrii. That which is most concerned with chemical knowledge, according to the nineteenth century chemist Berthelot, is the Leyden Papyrus X. This document was written in the third century AD and was found at Thebes: it contains large collection of recipes for alchemical and chemical operations, including gilding, silver plating, purifying metals and alloys, making purple dye, etc. These recipes are a starting point for ink and paint chemistry.

The Papyrus Graecus Holmiensis or Stockholm Papyrus is an Egyptian papyrus dating from the late third century or early fourth century AD, written in Greek and preserved at the Kungliga Bibliotek in Stockholm. This document is particularly important because it is the earliest surviving example of an alchemical text and, as such, is the oldest record we have of chemical practices and procedures. The papyrus was probably written in Thebes, and was discovered in a tomb in the nineteenth century. It was later transferred to Stockholm.

The Stockholm Papyrus provides a rich, though fragmentary, panorama of technical knowledge in Egypt and the Mediterranean in a period of transition between the classical era and the Middle Ages, though scholars believe that the procedures it describes are often far more ancient than the papyrus itself, and were passed down from generation to generation. The papyrus contains 159 recipes or chemical procedures, in no particular order (in practice, there are 155 recipes, as 4 are repeated), and the topics it covers include alloying silver, the use and fabrication of precious stones, and cloth. Much of it is symbolic or esoteric in nature, often reflecting the first, contemporary, alchemical doctrines, as exemplified by several procedures for creating or imitating gold and silver.

Seventh Century

Isidore of Seville, Etymologiae. Isidore, seventh century bishop of Seville and son of the governor of Carthage, wrote an enormous folio volume that compiled much of what had survived of classical learning in a sort of rustic encyclopedia. Book XIX has a section on colors, describing most of the lacquers mentioned by Pliny, chrysocolla (a native greenish-blue copper silicate), and purple.

Eighth and Ninth Centuries

Lucca Manuscript 490 or Codex Lucensis 490 in the Biblioteca Capitolare Feliniana of Lucca is a miscellany manuscript copied between 787 and 816 whose contents include a section entitled Compositiones ad tingenda, or Recipes for Coloring. The oldest records of the colors used in the Middle Ages are thus found in this eight century manuscript, which can be regarded as a vital link between compilations of the recipes used by artists and technological formularies.

It describes formulations based on cinnabar, litharge, ceruse, verdigris and orpiment, along with methods for coloring mosaic glass and dyeing leather and cloth purple and green. Procedures are given for preparing pigments and gold or silver inks, for coloring artificial stones, for dyeing hides and fabric, for gilding and for working metals and alloys.

It preserves miscellaneous recipes intended for teaching purposes, together with several ancient treatises such as Pythagoras’s Ars numeri, a fragment of Pliny on the division of time, and a method for calculating Easter. It is written in barbaric Latin, heavily influenced by Greek: a clear sign of its links with similar compilations of recipes from the Hellenistic period. Unlike other such compilations, it is unique, in the sense that only one copy exists.

Tenth and Eleventh Centuries

Mappae Clavicula, tenth century. A miscellaneous collection in Latin of around 300 technical procedures for various crafts and arts. The oldest copy dates to a period between the end of the eighth and the beginning of the ninth centuries, and is one of the oldest catalogs of recipes that has come down to us. Most of the recipes deal with procedures for preparing colors and transforming metals. Many of the recipes from the Compositiones ad Tingenda are reproduced. The colors mentioned are all mineral in origin, while gilding and dyeing are also covered.

Though several of the recipes in the Mappae Clavicula have been shown to come from the Leyden or Stockholm papyrii, some four centuries earlier (fourth century), the material in general is highly assorted, showing the influences of many different cultures: Greek (Dioscorides), Roman (Pliny the Elder), Byzantine, Arab and British. Other recipes contained in later codexes are carried over from the Lucca Manuscript, though in different order.

De coloribus et artibus romanorum by Heraclius or Eraclius. An important source for the history of dyes, pigments and the technical arts in general. The second section is entitled “On the use of the fresh juices of plants in miniature painting”, and provides detailed descriptions of how to prepare colors for illuminations and inks.

The introduction speaks of the lost arts of ancient Rome, whose memory should be kept alive throughout Europe: the author proposes to reveal them in his book, which must thus be jealously guarded by whoever comes into its possession.

Heraclius’s text consists of three parts, two of which are older, possibly dating from the eight century, and are written in Latin hexameters. The third section is in prose, perhaps from the twelfth or thirteenth centuries. A fragment of this text with sixteen recipes was found in Germany and can be dated to the eleventh century. Heraclius was probably a monk and, as has been suggested, lived in the Venetian territories in northeastern Italy.

The colors described for use in illuminating manuscripts (red from ivy, green from artificial and plant sources, orpiment for yellow and as a substitute for gold) are typical of eighth-century Italy, and of the northeastern part of the country in particular. These recipes are invaluable in helping us understand how medieval craftsmen made their works of art, how they created and applied their colors, and how they achieved particular effects. This collection devotes particular attention to literary form, showing the influence of concepts we also find in Vitruvius, Pliny the Elder and Isidore of Seville.

Eleventh and Twelfth Centuries

Theophilus Presbyter. Judging from his clear, detailed descriptions of the medieval arts, Theophilus, known as Theophilus the monk, must have been a practicing craftsman, and indeed a master of his craft, as well as a writer. His writings are more complete and orderly than their predecessors, and reflect all the richness and variety of Romanesque art and culture, as well as providing valuable insights into the history of medieval chemistry.

L’Escalopier’s translation divides the text into three books: the first deals only with colors, and how they are used and applied to various types of surface. It describes how to prepare many pigments, including ceruse, Spanish green or verdigris, cinnibar, minium, and others. Theophilus teaches the reader how to prepare glues to fix pigments, and is the first to recommend using linseed oil in paints.

Thirteenth Century

Petrus de Sancto Audemaro or Pierre de St. Omer, a monk from Northern France and near-contemporary of Theophilus, wrote “De Coloribus Faciendis”. He describes how to apply pigments to books, or in other words in illuminations, using gums or egg white. The manuscript contains the usual recipes for colors, inks and gilding. The colors mentioned include green, prepared in various ways from copper and from plants, white from lead, black from soot, blue from copper and plants. The red pigment was artificial vermilion, red lead, which the author calls minium or sandarac. His only yellow pigment was saffron, though this was used mostly for lacquers and varnishes.

Fourteenth Century

De Arte Illuminandi. As the title implies, this text deals only with manuscript illumination. It was found in 1872 in the Biblioteca Nazionale of Naples and is the work of an anonymous late fourteenth century Italian illuminator. It describes methods and recipes used personally by the author.

Fifteenth Century

Il Libro dell’Arte o Trattato della Pittura – The Craftsman’s Handbook – by Cennino Cennini da Colle Valdelsa, was first published by Giuseppe Tambroni in 1821. Cennini’s life spanned the late fourteenth and early fifteenth centuries, and his book deals principally with how colors were prepared at the end of the 1300s. Tambroni’s edition of the treatise was published in a number of languages, while corrections were added by Carlo and Gaetano Milanesi in the Le Monnier edition of 1859.

Jan van Eyck (1386-1440). Van Eyck is often credited with inventing oil painting somewhere around 1410, though Theophilus, writing in the twelfth century, already gives a clear description of grinding pigments with linseed oil. Before van Eyck, however, the linseed oil was used raw, and painters had to endure tedious waits between coats because of raw linseed oil’s slow oxy-polymerization.

Bolognese Manuscript or Segreti per colori. The “Secrets of Colors”, a fifteenth century manuscript now conserved in the library of the University of Bologna, provides us with an idea of the state of chemistry in the Italy of that day; among other dyestuffs, it mentions and describes the use of indigo. The work is divided into eight chapters; it discusses blue, and lapis lazuli or ultramarine blue in particular, and the various ways of producing it. In the third chapter, after describing how to make blues with the juices of several plants, it discusses methods for making indigo from woad. The fourth chapter teaches a number of ways of preparing verdigris or copper green.

The fifth chapter contains recipes for making a number of lacquers, while the sixth describes preparing purple or mosaic gold – aurum musivum, or stannic sulfide – with mercury, with tin (Venetian or Roman) and with sulfur, in various ways but similar to those described in De arte illuminandi. The seventh chapter gives several methods for preparing cinnabar with quicksilver (mercury) and sulfur, and the eighth chapter deals with dyeing a variety of materials.

Sixteenth Century

The sixteenth century was a period that saw major advances in oil painting. In Italy, the first true technical treatises dealing with all aspects of the arts were published. With the discovery of the Americas and the West Indies trade route, cochineal and indigo began to be imported, opening up a whole new range of possibilities for the color and dye industry.

Venice became a center for the preparation, purification and use of many pigments and dyestuffs; it was there that all of the colors needed in book decoration, writing and dyeing were prepared. The best indigo from India and Egypt arrived in Europe by way of Venice.

Venice also carried on a busy trade in cobalt blue, discovered by Schurer in 1565. Ceruse, or lead carbonate, was made in Venice and was thus known in the business as “Venetian white”.

Venice produced large quantities of many chemicals used in dyeing and painting – alum, for instance, and turpentine, which was thus often known as Venice turpentine. In addition, Venice was renowned for the colors used in enameling, mosaics and glassmaking.

Dyeing in Venice: “Libro di tintoria intitolato Plicto, che insegna a tenger panni, tele, bombasi, & sede, si per l’Arte maggiore come per la comune. Nuovamente stampato e ricorretto, in Venetia, appresso Lelio Bariletto, 1565 (1540). (The Plichto or Book of Dyes, which Teaches the Dyeing of All Manner of Woolen, Linen, Cotton and Silk Stuffs, by the Great Art as Well as by the Common, Newly Reprinted and Corrected, in Venetia, at the printworks of Lelio Bariletto, 1565 (1540). Though not indicated on the title page, this marvelous book of dyeing “secrets”, a true treatise on color chemistry, is known to be the work of Giovanventura Rossetti, a craftsman at the Venice arsenal who already had a claim to fame as the author of another “book of secrets”: Notandissimi secreti dell’arte profumatoria, or Useful Secret’s of the Perfumer’s Art (Venice, Francesco Rampazzetto, 1555). The Plichto is divided into four sections, in which a total of 225 recipes for dyeing fabrics and many other materials are minutely illustrated.

I Secreti del Reverendo Donno Alessio Piemontese. Work of the versatile sixteenth century writer Girolamo Ruscelli (under the pseudonym of Alessio Piemontese, often latinized as Alexius Pedemontanus), the Secrets went through many editions and was translated into a number of languages: Ruscelli was possibly a physician, or an amateur of the natural sciences and an alchemist. He spent many years traveling, gathering a quantity of recipes, formulas and procedures. He discusses illuminations, the preparation of various chemicals from minerals, how to imitate ebony, mordants, the many methods for painting metals, inks for writing and printing, and ways of preparing corrosive sublimate (mercuric chloride), cinnabar, and much more.

Théodore Turquet de Mayerne (1573-1655). Swiss-born, Mayerne was educated in Montpellier and Paris, and later in Germany and Italy. A follower of Paracelsian theories, he endorsed the use of chemical remedies. He was physician to Henri IV of France, and later to James I and Charles I. While living in England, Mayerne developed an interest in painting, and made extensive studies of the materials used in that art. He wrote a treatise on pigments for painters, and it appears that he learned the method for preparing them from the renowned portraitist Van Dyke, whom he numbered among his friends.

Seventeenth Century

De arte vitraria or The Art of Glass by Antonio Neri. Florentine chemist and priest, Antonio Neri traveled extensively in Italy and Holland. His writings are regarded as the most important source for the applied chemistry of the seventeenth century. They are of interest for the history of pigments, especially Book VII, which “shows how to make yellow lacquer for painters from broom-flowers, and all other colors; with another way of making lacquer, be it green, blue, purple and all hues from every kind of plant and flower ”.

Ricette per ogni sorta di colore or Recipes for every kind of color. This seventeenth century codex in the library of the University of Padua contains interesting descriptions of techniques for preparing many of the colors used at that time.

Eighteenth Century

It would be impossible to list all of the many works about colors, inks and paints published in the eighteenth century. Major advances were made in printing, and new pigments and dyes, including Prussian blue, mosaic gold and Scheele’s green, were discovered or synthesized through chemical research.

Nineteenth Century

With the burgeoning chemical industry, new dyes and pigments multiplied. The number of publications dealing with them is virtually infinite.

The use of Chlorinated Solvents as washing agents in the Metal and Steel Industries

 

I – Chlorinated solvents as washing agents
Introduction
Chlorinated solvents and related problems
Chloroethanes
Chloroethylenes
Chloromethanes
Cleaning Processes
Ultrasound degreasing
Main features
Precautions
Thermal decomposition
Evaporation
Storage
Distillation
Regenerated solvents
Checks
Toxicity
Production control

II – Related problems
Production and utilisation of tips for ball-point pens
Writing blocking
Metal enrichment into the ink in contact with brass parts
Nature of clots thats obstruct duct in ball pen tips
Verification of results and conclusions
III – Photographic examination
Photographic examination and subsequent discussion.

Picture n. 1 – 2 – 3 – 4 – 5 – 6 – 7 – 8 – 9 – 10 – 11 – 12 – 13 – 14 –
15 – 16 – 17 – 18 – 19 – 20 – 21 – 22 – 23 – 24

IV –

Report of the meeting
Report of the meeting held on June 4
Opening speech
Problem analysis
Analysis methodology and final results
Introduction to chlorinated solvents
Attentive use of chlorinated solvents
Importance of the equipment used for washing parts
Corrosion of machined but unwashed parts
Can the ink pH play an important role in corrosion?

Picture n. 25 – 26 – 27 – 28 – 29 – 30 – 31 – 32 –
33 – 34 – 35 – 36 – 37

Conclusion

 

Introduction

This document is intended to analyse the various problems related to the use of solvents known as chlorine derivatives and to sensitise users to their correct use with the aim of preventing corrosion in the final products.

This section will focus on the characteristics of chlorinated solvents normally used to degrease metals and on the problems that might accidentally follow the inappropriate use of the product.

The second section will concentrate on possible problems arising from the use of uncontrolled solvents.

A thorough analysis of the issue was made necessary by various defective cases registered all over the world in the last two years. Refills manufactured and sold were then rejected by final customers because they just stopped writing. Cases of that kind had never occurred before, nor was the origin of the defect known.

Chlorinated solvents and problems related to their use

Chlorinated solvents were introduced in the cleaning and degreasing of metals at the beginning of the Sixties: they are the most important class of substances belonging to the family of halogen derivatives. They replaced conventional oil products (special petrol and white spirit) with the disadvantage of being inflammable whilst chlorinated solvents are not.

They are polar substances endowed with a remarkable solvent power.

Chlorinated hydrocarbons usually possess a high solvent power with greases, rubber, chlorine, etc.

They are insoluble in water but can be mixed with other solvents; their sweetish smell is stronger than that of unchlorinated solvents.

It can be stated that chlorohydrocarbons are currently the main means through which chlorine is fixed and reaches the chemical market.

Chlorinated hydrocarbons can e subdivided into three main groups:

  1. Paraffin derivatives
  2. Derivatives of unsaturated hydrocarbons
  3. Derivatives of aromatic hydrocarbons

Chlorinated solvents are technically divided into:

  • Chloroethanes
  • Chloroethylenes
  • Chloromethanes

We will confine our analysis to compounds used in the metal and steel industry as degreasing agents for metals.

Chloroethanes

There are nine chlorinated solvents deriving from ethane; their constitution varies according to the number of chlorine atoms present in replacement compounds.

1,1,1-Trichloroethane

Thanks to its low toxicity this solvent has taken up a remarkable importance in the cleaning of metal parts. It is hydrolysed by hot water under pressure; the type of acid generated depends on the amount of water reacting with the solvent; more specifically the hydrochloric acid which is produced caused a significant corrosion.
Chloroethylenes

More commonly known as Chlorothenes, these are six chlorinated products derived from ethylene by replacement of one or more hydrogen atoms with chlorine atoms. The most widely used types are:

Perchloroethylene

It is conventionally used for the degreasing of metals. It is not stabilised and exposed to water and light it can undergo a slow oxidation process with consequent release of toxic and corrosive substances.

Trichloroethylene

It is commonly used in metal degreasing. In the absence of inhibitors or stabilisers, Trichloroethylene slowly oxidises in contact with air and generates hydrochloric acid, thus becoming corrosive with all metal surfaces. Impurities contained in this chlorinated solvent are not allowed to exceed 10 parts per million acidity, 10 parts per million insoluble residue, and what is very important, 100 parts per million water.

Chloromethanes

They are four products obtained from the gradual replacement of methane hydrogen atoms with chlorine atoms. The most well-known is Methylene Chloride.

Methylene Chloride


Methane chlorinating has a specific importance and interest because it is the only technology allowing for the production of all the series terms. Because of its high volatility, it is not normally used in metal degreasing.
Table 1

Flash Point Molecular Weight Boiling Range (°C) density (20°)
Methylene Chloride Not Inflammable 84,94 Between 39,5 and 40,3 1,330
Perchloroethylene Not Inflammable 165,85 Between 120 and 122 1,623
Trichloroethylene Not Inflammable 131,40 Between 86 and 87,5 1,464
1,1,1-Trichloroethane Not Inflammable 133,42 Between 73 and 75 1,320
Cleaning Processes

The following factors should be taken into consideration when choosing the most appropriate cleaning method:

– Cold processes, though being direct and not requiring special equipment or technologies, lead to a high loss of solvent during the mechanical action accompanying the process and carry the risk of polluting the surface,

– Processes based on heat, besides allowing for solvent re condensation and therefore reuse, have a greater cleaning efficacy.

During solvent re condensation however, there is the danger of a greater concentration of water. The most widespread degreasing methods in industry are as follows:

  1. Hot degreasing with solvent vapours
  2. Cold degreasing by shaking, immersion, sprinkling
  3. Ultrasound degreasing
Ultrasound degreasing

This is the method affecting the sector of writing instruments directly and therefore the method we will be dealing with in this document.

It is well-known that the motion of the cleaning solution or of the object to be cleaned improves and accelerates the cleaning process. Ultrasounds are a practical application of this theory.

Ultrasound energy is by definition a high frequency mechanical vibration: a 50 hertz alternating current is sent to a generator developing a frequency of 20.000 cycles a second, or even higher.

Transducers turn electric power into sonic energy and then into sound waves; the latter are further transmitted to a fluid, thereby generating cavitations.

The cavitation mechanical action coupled with the solvent chemical action produce an effective degreasing process.

Ultrasounds start to remove fuel oil deposits and solids adhering to metal surfaces that are usually insoluble in conventional solvents.

Ultrasound cleaning is particularly useful for the removal of impurities in areas difficult to access.

In order to ensure an optimal ultrasound degreasing, operating temperatures should be 10-20°C lower than the solvent boiling temperature.

Main features of solvents used for metal degreasing

The main features of these solvents are:

a) Non inflammability: it is one of the main reasons why they are industrially used to degrease metals.

b) High solvent power: they can solve all kinds of greases, oils, waxes and resins used in the metal and steel industry during the production process.

Along with positive features we should like to mention some negative ones, and namely:

a) They are reactive to metals: chlorinated solvents, if not appropriately stabilised, may cause corrosion, stains and oxidation in metal parts.

b) They are unstable in the absence of inhibitors.


Precautions in the use of chlorinated solvents:
Water contamination

Water contamination is the most common cause of corrosion.

When a mixture of any chlorinated solvent and water comes into contact with metal parts, corrosion may occur.

Corrosion occurring inside the degreaser may also stem from thermal decomposition and the consequent formation of acid. This situation may be caused by a solvent overheating locally because of an excessively high temperature of the irradiating surfaces; it may also stem from high boiling point caused by too much oil.

The formation of acid (induced by hydrolysis of the solvent used) may also be the result of inadequate cleaning and maintenance of the equipment.

The careful removal of water that happens to be in the solvent is of the utmost importance to avoid the following inconveniences:

– Condensation of air moisture in the heating coils used for solvent re condensation.

– Presence of aqueous emulsions of blending oils on the parts to be treated.

– Presence of water on machined parts.

To avoid all this, each machine used for washing should be equipped with a very effective water separator.

Moreover, the amount of water present in solvents should be kept under 200 PPM; when this amount increases and reaches 450 PPM (which corresponds to 450 grams of water every 1000 litres of solvent !) the solvent must no longer be used but immediately distilled or passed through a water separator.

To confirm this, suffices to mention that the aqueous extract of a solution of 10 cc of stabilised but old 1,1,1-Trichloroethane with 90 cc of water at ambient temperature moves from pH 7 to pH 4 in 24 hours; with the increase in temperature, the pH goes down to 3.

If the same solution is exposed to sunlight for 48 hours, it reaches a very high acidity (pH 2,8).

It should be considered that water together with solvent may form an azeotropic mixture, that is a mixture of two or more liquids with a constant boiling point, that does not change composition, not even after a distillation.

A binary mixture may be characterised by a boiling point lower than that of the most volatile component and higher than the least volatile one.

It is because of the danger on introducing water into the tank that the machine must have a water separator with a capacity proportional to its working capacity.

Furthermore, to make separation easier, operating temperature should be decreased so as to reduce solvent solubility in water.

Table n.2 shows a number of parameters related to water-solvent azeotropic mixtures.

Table 2

Azeotropic water-solvent mixture boiling point (°C) Azeotropic mixture weight percentages Corresponding to (ppm)
Methylene Chloride 38,1 1,5 water
98,5 solvent
15.000
Trichloroethylene 73,3 5,4 water
94,6 solvent
54.000
Perchloroethylene 87,8 15,8 water
84,2 solvent
158.000

Thermal decomposition

No chlorinated solvent should be used when there is even the slightest likelihood that vapours in a given pp concentration might come into contact with live flame, when surfaces are too hot, or when a distillation with too much oil or too little solvent has been carried out. This may lead to decomposition with the subsequent formation of hydrochloric acid, chlorine, carbon dioxide, carbon oxide and phosgene.

Luckily, the irritating action of hydrochloric acid clearly indicates the beginning of this decomposition, long before phosgene concentration reaches dangerous levels.

It should also be kept in mind that besides causing toxicological problems, decomposition by-products corrode the metal parts they come into contact with. Table n.3 shows that the starting temperature of thermal decomposition is higher for Trichloroethane than for the other chlorinated solvents conventionally used in metal degreasing. Moreover, Trichloroethane produces by far fewer decomposition toxic substances.

Table 3

Thermic decomposition starting temperature (°C)
1,1,1-Trichloroethane 163
Trichloroethylene 120
Perchloroethylene 140

Evaporation

The choice of too volatile solvents like Methylene chloride should be avoided for two main reasons:

1) In certain atmospheric situations, steam contained in the air may condense on the metal surfaces cooled by the quick solvent evaporation and consequently increase water concentration;

2) An excessive solvent evaporation leads to a sudden increase in the water-solvent ratio.

In both cases an azeotropic mixture may be the result.

Storage

Solvent drums must not be kept for long in humid places to avoid a possible corrosion of containers and the subsequent solvent contamination.

As far as the storage in tanks is concerned, excellent results are obtained with stainless steel tanks with lined internal walls, so as to avoid any possible corrosion due to moisture.

Before using a container to store chlorinated solvents, one must make sure it is clean, dry and free from rust or metal chips, or from any oil traces that might trigger deterioration processes.

Distillation

Here are important instructions to be followed in the distillation of chlorinated solvents:

a) Separate the water layer that might possibly cover the solvent before carrying out distillation.

b) Remove possible chips and powders from the solvent before distillation.

c) Collect the contaminated solvent into clean stainless steel or plastic containers, since the presence of rust may catalyse the impoverishment of stabilising agents.

d) Use a system of stabilisers with a boiling point as close as possible to the solvent boiling point so that both go together during distillation.

Inhibitors present in chlorinated solvents play an essential role in reducing the risk of metal oxidation.

An incomplete distillation or insufficient equipment cleaning frequency may lead to an excessive loss of inhibitors during solvents utilisation or distillation.

A regular re-stabilisation of chlorinated solvents is very important to avoid corrosion and oxidation.

For this reason every user must carry out a check at regular intervals to assess the amount of stabiliser necessary to protect chlorinated solvents from acidification.

Regenerated solvents

The purchase of regenerated chlorinated solvents in the market may help you save money but may also cause inconveniences to the user if he is not informed well enough. Indeed it should be remembered that even a chlorinated solvent only partially degraded after distillation may become acid and therefore corrosive, with serious damage both to the equipment and, more frequently, to metal parts.

The best way to avert these risks is refraining from buying regenerated solvents from unknown sources or reckless suppliers.

Even a “home made” regenerating must be carried out with high-quality solvents; it is a simple operation, but it requires some attention and skills.

Remember that washing baths should never contain brass chips or powder (if present they must be promptly removed) since they catalyse the decomposition process.

Checks

Regular checks are recommended by all solvent manufacturers to maintain the cleaning system in optimal conditions and to ensure effective degreasing operations.

Some of these checks are very simple and do not require special equipment or chemical know-how; they can be carried out by the operators themselves.

Here are the most well-known control methods:

  1. Acid acceptability test
  2. Scratch test
  3. Aqueous extract pH test

The scratch test is generally used to assess the stability of solvent with aluminium and therefore it does not fall into our scope of analysis; the acid acceptability test is normally used to assess the amount of stabiliser present necessary to protect the solvent from acidification.

The simplest method known is the aqueous extract pH test; the necessary material can easily be found.

To carry out this test put 50 ml of chlorinated solvent in a clean container previously rinsed in distilled water, add the same volume of distilled water previously brought to pH 7 with a normal-hundred HCl solution, and shake for about two minutes.

Leave to separate and finally dip electrodes of the pH-meter into the water and measure.

The pH should be as close as possible to 7. Lower values indicate that the acidification process has already started and that the solvent must therefore be regenerated.

All manufacturers can rely on laboratories with qualified experts at the customers’ disposal for technical tests or consultancies; users may even be supplied a “test kit” for a quick and easy assessment of solvent stability.

Toxicity

Every person responsible for the operation and maintenance of degreasing equipment based on the use of solvents should be well-trained to its correct use.

Every user should precisely know all the risks related to the use of chlorinated solvents; it is only this way that, with some precautions, they can be used safely.

Trichloroethylene and Perchloroethylene are marked by a similar photochemical reactivity, but Trichloroethylene develops a significant amount of photo-oxidation derivatives which may lead to the release of a photo-chemical “smog”.

Among these products, the most important one are: chlorine, hydrochloric acid and phosgene.

The most dangerous one is phosgene; besides being highly toxic, it has no property based on which it can be identified and has delayed toxic effects.

Not in all chlorinated solvents the decomposition process releases an amount of phosgene hazardous for health.

Trichloroethane for instance releases very limited amounts of phosgene and only during arc-welding processes.

Users of chlorinated solvents are highly recommended to abide by the following vital instructions:

  • Use solvents with a limited toxicity.
  • Use of appropriate and controlled equipment.
  • Use of distillation plants.
  • Development of preferential business relations with solvent manufactures able to guarantee an excellent technical service.

Table n.4 shows the toxicological properties of chlorinated solvents most commonly used in metal degreasing. 

Table 4

 Smell Effects
Perceptibility threshold (ppm) Weak (ppm) Irritating (ppm) None (ppm) (8 hours) Eyes Irritation (ppm) Respiratory Diseases (ppm) Coordination Lack (ppm)
1,1,1-
Trichloroethane
100 350 1.000 500 1.000 2.000 1.000 (30-70 min.)
1.500 (15-60 min.)
2.000 (5 min.)
Trichloroethylene 100 200 600 100 400 (weak) 1.000 (strong) 1.000 400 (20 min.) 1.000 (6 min.)
Perchloroethylene 50 150 400 100 400 600 200 (8 hours) 400 (2 hours) 600 (10 min.)

Production control and use of chlorinated solvents

In November 1992 in Copenhagen, during the fourth Meeting of the European Community, the application rules of the Montreal protocol were modified. The protocol laid down the rules to be followed in production control and use of Chlorofluorocarbons, Hydrochlorofluorocarbons, Carbon Tetrachloride and Trichloroethane.

Trichloroethane had already been included in the group of products regulated by the 2° Review Meeting held in London in June 1990.

Here are Trichloroethane control measures according to the latest application rules:

Production freeze: January 1, 1992 at 1989 levels

50% reduction: January 1, 1994 at 1989 levels

Total elimination: January 1, 1996.

The only derogation still in force apply to Underdeveloped Countries to meet the needs of their domestic markets.

It should be noted that the Montreal protocol provides for general rules only, therefore some countries might decide to set more restrictive rules to accelerate the reduction and elimination of Trichloroethane.

Second Section
Problems related to the use of chlorinated solvents in the production and utilisation of tips for ball-point pens.

The first part of this document has provided a broad illustration of metal degreasing methodologies and of the problems that might arise in the utilisation of chlorinated solvents.

This second part will analyse the practical implications of a number of problems recently emerged in the production of refills.

At the beginning of 1993, talking to a solvent technician working for a multinational company in the sector of chlorinated solvent production, we learnt that two years ago approximately all chlorinated solvent manufacturers had to give up the use of stabilisers like 1,4-dioxan because of toxicological problems. Such stabilisers were deemed highly toxic because of their very dangerous vapours.

Moreover, dioxan is considered noxious to the mucous (eyes and lungs) and is absorbed by the skin.

All the problems occurred in the production of refills all over the world which caused a lot of troubles to both users and manufacturers date back to that period, but only very recently an explanation could be found.

All industrial sector using chlorinated solvents to degrease metals ran into the same problems.

The identification of their cause was neither simple nor immediate; solvent manufacturers did not have sufficient information at their disposal and the problem was totally unprecedented. Up to that moment REINOL had never encountered problems in the use of inks for ball pens.

Several tests were carried out both internally and by external laboratories to come to a correct data interpretation. They were made necessary by the far-reaching implications of the issue and by the difficulty in finding a solution.

Analysis of the first anomalies occurred and search for the cause of writing blocking.

The first complaints arrived in July 1991; a Korean customer complained for the presence of defective refills: they usually started to write, but after a while, the writing specimen became irregular until it totally stops.

By insisting on moving them some refills started to write and became gradually normal again.

The stop of writing into the refills is normally due to the following reasons:

1) The ink thickens and increases viscosity.

To check this instance, our laboratory measured viscosity with a computerised viscometer Haake Rotovisco Rv-20 equipped with a PK5-1.0 probe.

Thanks to this equipment our laboratory is able to carry out the analysis of ink viscosity even with a limited number of refills.

The ink of these defective refills revealed value in compliance with the warranted characteristics.

2) Ink crystallisation.

We analysed at the microscope a counter sample of ink sent back by the customer, but no crystallisation was observed; the ink on the slide was limpid and pure with no alteration.

3) Formation of a plug at the bottom of the tube due to a wrong ink formulation or to an early ageing on ink itself.

All tests carried out excluded the possibility that ink might have formed a dry plug at the bottom of the tube (in this case the consistency of ink was always normal) and also excluded the formation of corrosion in the tip shoulder area.

The latter observed at the microscope always appeared perfectly clean and free from any oxidation (see picture n. 1).

In this respect it is worth remembering that raw materials used in the production of inks are made of chemically pure compounds and their formulas are by their very nature constant and invariable; in the opposite case, their specific features would be totally upset.

In the case of dyes, for instance, the substance colour depends on the specific arrangement of atoms in the molecule.

All coloured organic substances are unsaturated compounds, that reduced with hydrogen loose their colour.

A few cases will now be illustrated to better explain the above-mentioned concepts:

Phtalic Imide Isatin

In this case it was enough to change the arrangement of the -NH group and the carbonyl group (>C=O) to completely modify the characteristics of the product obtained (phtalic imide is colourless whilst isatin is orange).

Yellow Colourless Colourless

To check the quality of the ink we replaced a number of tip with new ones and then proceeded to the various ageing tests.

All refills treated this way could write normally.

The only unexplored instance left was ink flowing in the tip internal duct and more specifically the ink close to the ball.

We carried out a new test in our laboratory, we removed the ball and collected the ink on a slide for subsequent observation at the microscope.

The ink turned out to be turbid, with unknown clotted particles.

Our customer carried out a well-structured laboratory test with the following results:

1) The ink analysed at the microscope was limpid.

2) The ink contained in refill tips had white insoluble spots(see Annex A: Customer’s “TEST REPORT”).

Moreover, tips showed a corroded area on their outer wall as it can easily be observed in pictures n. 2 and 3.

At the same time, when the first problems arose, our laboratory sent some refills to SGS Laboratories Ecology Department for a more accurate examination.

SGS Ecology
Technical evaluation of possible metal enrichment of ink in contact with brass parts.
Since the defect (writing blocking) was believed to be due to the presence of brass powder not totally extracted during washing, zinc, copper and lead samples were taken from three different areas in the refill.

Three samples were obtained:

  1. in direct contact with the ball
  2. in the bottom part of the tip
  3. in the polypropylene tube at 5-6 cm. from the tip.

The latter was considered the reference sample since it does not come into contact with the metal parts of the refill itself.

The different samples obtained were mineralised with an acid mixture (HCl -HNO3) and a hot process so as to destroy the organic matrix and produce a solution.

To check the presence of metals a plasma spectrophotometer with sequential reading was used.

Results showed (see Table n. 5 and Annex B) a greater concentration of the three metals in the bottom part of the tip which according to the SGS laboratory is due to the presence of brass powder caused by a “non perfect cleaning of the tip after the lathe operations”. This powder creates a wider contact surface and increases the likelihood of brass mineralisation. To confirm or reject the assumption put forward by the SGS Laboratory we had to experimentally reproduce the defect in our laboratory.

Table 5

 Parameters C (mg/kg) B (mg/kg) A (mg/kg)
Lead < 0,5 40,9 < 0,5
Copper < 0,5 46,1 < 0,5
Zinc 6,6 67,1 < 0,5

To this aim, we formulated a number of different inks mixing with them some brass powder resulting from the tip lathe operations.Refills assembled with these mixtures wrote with no defect at all, neither immediately nor after the ageing test.

Given the tiny amount of defective product, the analysis of A samples did not produce reliable results.

At this point, we had to go into greater details using an electronic microscope to find out the nature and origin of the clot inside the tip.

We entrusted the Chemical Laboratory of the Chamber of Commerce in Turin with this task.

With the aim of identifying the nature of the clots which are probably the root cause of the hole obstruction in our brass ball point refills, a scanning electron microscope (JEOL 6400) equipped with an EDS probe was used (X-ray energy dispersion spectrometer TRACOR Z-MAX 30). See Annex C.

The EDS analysis, as it can be easily observed (Chart n. 2 and Picture n. 18), highlighted as basic elements agglomerates of copper with zinc and chlorine. Their arrangement perfectly overlaps with that of the clot removed from the tip (see Picture n. 4).

In some cases the procedure highlighted only the presence of copper particles and this puzzled operators.

The same instrument was used to measure the various elements present in a brass tip free from corrosion (see Chart n. 1). In this case no particle of chlorine was observed.

After a first microscopic observation with a magnification power of x100, the magnification was increased to 1.500 to assess the crystalline structure of the elements making up the unknown agglomerate (see Picture n. 5).

Then we started looking for the element with the same crystalline structure observed at the microscope. After the analysis of several pure particles and artificially created products, the optimal result was obtained using some brass powder (see Picture n. 6).

The size of particles forming the agglomerates is about three micrometers and their crystalline structure matches that of pure electrolytic copper powder.

One of the doubts expressed by our experts referred to a possible contamination of ink at its finale stage, caused by an imperfect purification during the final stages of the production process. This could have led to an accumulation of insoluble particles inside the ball feeding duct during refill centrifugation.

To side-step this problem, one of the first checks carried out at the end of the production process is the centrifugation of some refills assembled with the ink under study. This operation which takes a long time (30 minutes approximately) is followed by a microscope analysis of the ink located behind the ball to verify the actual absence of insoluble parts.

To this purpose our experts prepared an X-ray 120 magnification map of insoluble residues obtained during ink purification at the centrifugation and filtration stage scattered in an area of 0,85 square centimetres (it should be pointed out that REINOL utilises a single process, with two filtrations and one centrifugation stage).

The map (see Annex C) highlights the presence of particles containing iron, silicon, calcium, sulphur and aluminium in a smaller percentage, and just one single copper particle.

If we compare the results of this map with the previous one, we can notice the actual efficacy of the purification process: indeed none of the particles present in residues is found in ink at its final stage.

Based on these results one could think that refills stopped writing because of an excess of brass powder or chips due to an insufficient cleaning and washing; however, the fineness of particles (3 micrometers) and the unusually high quantity could have been traced back to a bad washing of tips, but also to a cause which remained unknown for the moment.

The chlorine found during the EDS analysis (see Chart n. 2) was not taken into account at that stage simply because the hypothesis of corrosion had not been considered yet.

Verification of results and conclusions

Experimental test were needed to reproduce the same circumstances in the laboratory and to check whether the root cause of the writing defect was in brass contamination or in other substances normally used in the ball tip production process and in the subsequent refill assembly.

Inks were therefore contaminated with different percentages of the following products:

– very fine powder obtained from the machining of tips. Due to the greater surface in contact with ink, it is much more reactive than the tip brass;

– new blending oil used for the machining of tips;

– used blending oil with brass chips.

These mixtures were then used in the assembly of some control refills that were subsequently subjected to a number of tests, ageing tests included.

All refills thus obtained and assembled were operating perfectly. This meant that the writing blocking in defective refills was not due to the presence of brass (powder or chips) caused by a bad washing of the tip itself.

Some observations had already led us to think that the final explanation was to be found in a different direction, namely:

– The defect occurred both in tips supplied by experienced and excellent manufacturers and in products supplied by minor manufacturers with little experience in the field.

– The same defects recurred using ink supplied by different manufacturers.

During our study, we received refills from all over the world. They were filled with both our products and with inks supplied by competitors – they all had the same defect.

The time frame could be easily identified and it was the same for all manufacturers.

The EDS analysis clearly highlighted the presence of chlorine particles that do not belong to the composition of brass, nor to the formulation of inks.

The use of unwashed tips, dirty with oil, did not produce any defect, even after one year and a half of tests. Tips remain shiny and clean.

At page 49 Picture n. 7 shows a tip as it usually appears.

Our laboratory was developing a project for a very important customer. For the project it used ink formulated in the laboratory and tips of a very high quality. But there again, after about six months, all assembled refills stopped writing. This was the clue to look for different causes. The defect could no longer be ascribed to a bad ink formulation, that in this case had been produced in the laboratory with the help of precision micro-balances and therefore with an error rate of 0,001 grams for 100 g. of finished products!

The clue to the solution was provided by the observation of a number of tips with clear signs of acid corrosion on the inner duct of new tips coming from different manufacturers as it can be noticed in the following pictures:

– Pictures n. 8, n. 9, n. 10, n. 11, n. 12, n. 13, n. 14, n. 15

– Picture n. 24

In this case corrosion is caused by the etching of hydrochloric acid formed through hydrolysis of the chlorinated solvent and is due to phenomena explained in the previous section.

It should be noted that hydrochloric acid is by far the most aggressive in etching brass followed by nitric acid, whilst sulphuric acid produces a weaker effect.

The term brass encompasses a wide range of Copper and Zinc alloys, where the latter is in a percentage not exceeding 50% (usually this percentage varies from 11% to 50%).

Zinc reacts easily to acid and develops hydrogen:

Zn + 2H+ < = > Zn++ + H2

and

Zn + 2HCl < = > ZnCl2 + H2

The greater the amount of impurities in Zinc, the easier the above-mentioned reaction.

Zinc chloride is deliquescent substance, that is a highly hygroscopic salt with the property of turning into a solution by absorbing water from the surrounding atmosphere. This situation highly increases the reactivity of chloride itself.

Even copper melts in any acid if exposed to air.

With hydrogen halide acids, like for instance hydrochloric acid, copper oxide forms insoluble copper salts which precipitate:

2Cu + HCl < = > 2CuCl + H2

This acid etching is followed by the formation of zinc, lead and copper salts.

Brass oxidation and the consequent formation of the so-called “saline efflorescence” leads to the formation of insoluble particles mixed with ink in the duct behind the ball. An example of this acid etching on brass, with the consequent formation of saline crystals, was already registered in nickel-plated tips at the end of the machining process in 1984 (see Picture n.17).

To avoid this problem, manufacturers started to machine tips only after the nickel-plating process.

In other cases acid etching may be caused by factors not linked to washing products but to the raw materials used during the forming process (Picture n. 17).

The ensuing copper and zinc oxides are highly reactive to certain ink ingredients and produce insoluble substances, usually copper and/or zinc carboxilates. These compounds alter the normal rheology of the ink, decreasing its ability to flow into the capillary duct.

The degeneration process occurs in three distinct stages:

Stage 1: At this stage a weakening of the writing specimen occurs; it is due to a narrowing of the tip inner duct and therefore to a smaller amount of ink flowing through.

Stage 2: Salts continue to increase with consequent writing “gaps”.

Stage 3: It is the final stage of the degeneration process when tips just cease to write altogether.

Some refills however, if subjected to centrifugation, start to write again reasonably well, gradually improving until the ink flowing out has not brought out with it all saline particles.

The salt content of these refills is smaller and has not caused a total duct occlusion yet.

In refills which do not start writing again the salt content has totally blocked the capillary duct.

If we slightly blow the refills, writing starts and gradually becomes normal again. Even after ageing test, the performance of refills processed this way remains normal.

This is in line with the results of some tests carried out by our competitors. They demonstrated that by replacing or washing the tips of defective refills, but using the same ink, the problem did not crop up again.

Furthermore, there is the possibility that in some tip lots, the capillary duct might have already been totally obstructed.

In the light of these data, the results of all the tests carried out by external laboratories fine an easier explanation:

– The high copper and zinc percentage in the tip ink stressed by the SGS analysis confirms the high content of the two metals in ionic form, which therefore passes into ink.

– Copper and zinc particles found in all tests carried out by the Chemical Laboratory of the Chamber of Commerce are in fact Zinc and Copper salts, as it can be easily observed from Charts n. 1 (EDS analysis carried out on a brass tip with no writing defect: no chlorine, copper or zinc particle is found to be part of the brass alloy) and n. 2 (EDS analysis of the waxy clot behind the ball of a tip belonging to a defective refill: the two above-mentioned salts are not only made of copper and zinc, but also of a certain amount of chlorine.

– This explains why replacing the tips of defective refills with new tips all anomalies are avoided.

Corroded tips probably account for a negligible and sporadic part of production.

To check the accuracy of our conclusions, we experimentally reproduced the defect in our laboratory. We dipped for few minutes some etch-free tips in a 0,1 normal solution of hydrochloric acid (which amounts to 3,5 g. of HCl dissolved in a litre of water). After a few days the tips had the same problems of those contained in defective refills; this is clearly shown in Picture n. 19 and 20.

Over a subsequent set of tests carried out at the Chemical Laboratory of the Chamber of Commerce, we tried to ascertain the origin of saline efflorescence using manifestly defective refills and tips coming from Korea.

Here are the findings of the analysis of saline formations:

1) Brass undergoes a selective oxidation of its components;

2) Displayed saline efflorescence is primarily made of Zinc and Lead salts.

Picture n. 21 and 22 are very helpful in explaining these findings.

At the same time a scanning electron microscope was used to observe a saline formation found in a recently produced tip (see Picture n. 23).

The EDS analysis clearly shows that this crystal is made of Zinc salts.

Result of the EDS analysis carried out on a new and corrosion-free brass tip.

Result of the EDS analysis carried out on the clot behind the ball of the tip of a defective refill.

Third Section
Photographic examination and subsequent discussion.
After dealing with chlorinated solvents and their use as degreasing agents in industrial mechanical machining operations and more specifically going into the details of their application in the industrial sector of writing instruments, we felt it appropriate to carry out a case by case analysis of an issue involving manufacturers of all countries world-wide.
To avoid causing any damage to the manufacturers hit by this problem, we decided not to reveal the origin of defective tips and refills.
Her are the areas mostly affected by the defect:

  • North America
  • China
  • Germany
  • Centre America
  • Italy
  • Korea
  • Sri-Lanka
  • Thailand

We would like to draw your attention on the fact these pictures account for only a part of all pictures examined and come from uniform lots in terms of the defect.

Picture n. 1 – 2 – 3 – 4 – 5 – 6 – 7 – 8 – 9 – 10 – 11 – 12 – 13 – 14 –
15 – 16 – 17 – 18 – 19 – 20 – 21 – 22 – 23 – 24
Fourth Section
Report of the meeting held on June 4 at the JET HOTEL at Caselle (Turin)

The following companies were present or represented:

We would also like to thank for their presence and collaboration offered during the study:

Mr.Tinazzi, Chemical Engineer of the Chemical Laboratory of the Chamber of Commerce who put at our disposal the scanning electron microscope mentioned several times during this work.

Mr.Beltramino of C.I.A.T. who thanks to his twenty-year experience in the field of chlorinated solvents has given us precious help in the understanding of problems related to the use of halogen derivatives.


Opening speech
(Massimo Gippa – REINOL)

At the beginning of meeting participants were given a warm welcome and thanked for their active participation.

All tests carried out to find out the cause of the defects occurred over the last two years made it clear that the problem could not be solved by our company alone, but that it required the co-operation of all manufacturers. Based on this consideration we decided to summon this meeting – indeed the issue turned out to be far more complex than it was originally thought.

Each participant received a dossier summing up the topics to be dealt with during the meeting (subsequently the dossier formed the basis to draw up this book which is not meant to be a technical manual, nor an exhaustive analysis of all possible issues. It is just intended to become a term of reference for the future, to remember the findings of this work and the way it was communicated to all participants).

the aim of this meeting is not just solving now a problem cropped up in the past and explain its causes. The objective is to lay the basis for a future technical co-operation to prevent the occurrence of new problems that could indiscriminately affect manufacturers of tips, ink and finished products and undermine the image of us all.

We did our best to summon all manufacturers of the items involved in the production process of a pen, since it is only through perfect collaboration that the problem can be totally eradicated.

Many of you , despite your interest in the matter, could not participate because of various reasons, but they will receive a full account of the meeting. The topics and issues examined are both of a toxicological and environmental nature.

Toxicological problems that brought to the elimination of certain products belonging to the production process of ball-point pens.

There are environmental problems too because difficulties in the disposal of manufacturing by-products let to an inappropriate use of the products themselves.

During the opening speech, the opportunity was taken to thank two persons whose work has been essential to advance our research study:

– Mr.Tinazzi (expert in the use of the scanning electron microscope put at our disposal by the Chemical Laboratory of the Chamber of Commerce);

– Mr.Beltramino (who, thanks to his twenty-years experience in the field of chlorinated solvents, was extremely helpful in explaining the problems related to their use).

We divided the meeting into three main topics for discussion:

Mr.Buzzetti started up illustrating the specific issue and the results of tests reported in the first part of this text.

Subsequently, Mr.Tinazzi explained test procedures and will show the first findings.

Finally Mr.Beltramino went into the issue of chlorinated solvents, their properties and the most appropriate way of using them to avoid risks of any kind.

The opening speech was closed expressing the hope that the meeting could be helpful to all of us, not just to collect information on what REINOL discovered, but to promote an exchange of the experiences gathered so far by the different manufacturers.


Problem analysis
(Pietro Buzzetti – REINOL)
The need to carry out a very detailed analysis of the problem and to organise a conference to discuss the results and summon the highest possible number of tips, ink and finished product manufacturers is dictated by the unprecedented nature of the situation.

Since the problem was registered exactly the same way despite the use of materials (tips and inks) supplied by different manufacturers, it was originally felt that the cause had to be searched for in a defective component of the writing instrument.

Right from the start our engineers took into account all possible variables of the production process of defective refills, with special attention to inks; all raw materials used were thoroughly analysed (moreover they were never changed over the last few years). Every single finding of the test confirmed that the cause had to be found elsewhere.

The engineers’ work was not easy: a sight analysis of assembled refills was made more difficult by the presence of the dye.

Thanks to the help of the Chemical Laboratory of the Chamber of Commerce and to a fortuitous case, we were able to identify the cause of the writing blocking in a lot of new tips coming from Far East, which already showed macroscopic signs of corrosion.

Mr.Buzzetti went on to describe what is reported in the second section of this text and to show the slides the copies of which are to be found in the third part of this volume.

At the end of his contribution, after mentioning the usefulness of the electronic microscope in our research several times, Mr.Buzzetti asked Mr.Tinazzi (Chemical Engineer of the Chemical Laboratory of the Chamber of Commerce) to illustrate the analysis methodology used and to explain in simple words the operation of the instruments applied during the tests.


Analysis methodology and final results
(Silvio Tinazzi – CCIAA)

Mr.Tinazzi started of f with a description of the research methodology used between January 1992 and June 1993 and briefly showed the instruments applied: a scanning electron microscope JEOL 6400 with a resolution power of about 100 A at 35 Kv and magnification potential up to 300.000x.

The scanning electron microscope (SEM) displays three-D images with a remarkable depth of field. Its monitor does not record primary electrons which would affect the sample being studied and possibly cross it, but the secondary electrons emitted by the sample following the clash of primary electron beams. Moreover secondary electrons, in contrast with primary electrons, are not to be focused but just collected.

Another advantage of this instrument is its wide range of magnification power (you can start from a very low magnification like 10-15x) that provides a more detailed analysis leaving the depth of field unchanged (notice the sharpness of Picture n. 21).

Since each element has a specific emission spectrum, X-ray were used to analyse the various materials. The detection system used in the tests carried out at the Chemical Laboratory of the Chamber of Commerce in Turin consists of an EDS probe (X energy dispersion spectrophotometer TRACOR Z-MAX 30).

With the conventional X-rays detection instruments elements like Carbon, Nitrogen, Oxigen, Fluorine, Litium, cannot be detected. For this reason a NORVAR window has been used through which these elements can pass despite the low energy of their radiations.

This system is made of two plates with a thin silicon-lithium crystal in-between: when an X radiation hits the crystal, its ionises it and generates a current specific to that element.

In the final tests carried our by the Chemical Laboratory of the Chamber of Commerce, tried to verify whether the defects registered up to that moment could be traced back to a single cause, that is the acid corrosion of ball-point pen tips caused by the inappropriate use of chlorinated solvents during washing. Based on this a thorough examination of the following samples was carried out:

a) Defective refills. nickel-plated tips and competitors’ ink (Annex D Sample 1)

The tip taken from a defective refill was lightly washed with butanol so as to extract ink without affecting inner parts.

The washed tip was subsequently observed at the electronic microscope with two well-defined landmarks:

– Ball seat (See Picture n. 25);

– Inner wall behind the capillary duct (see Picture n. 26).

The analysis of Picture n. 25 reveals hollow formations and uneven profiles due to a starting corrosion process which becomes even more evident in the inner part of the tip where hollowness is much more visible and widespread (Picture n. 26).

b) Artificially polluted Reinol ink (see Annex D samples 2 and 3)

To conform the origin and chemical-physical constitution of this gelatinous mass, we artificially polluted our black ink 101/MG for ball-point pens with Zinc and Copper Chloride.

The ensuing mixture was analysed at the electronic microscope (Picture n. 27 and 28).

Especially in the case of contamination with Copper Chloride, the mass corresponds to the one already observed during previous observations of ink present in defective refills (Picture n. 5 and 30).

c) Defective refills: X-10 tips and Reinol ink (see Annex D sample 4).

We first examined the tip to check whether corrosion had already started or not.

The tip taken from a defective refill was lightly washed with butanol so as to extract the ink present without affecting inner walls.

The washed tip was subsequently observed at the electronic microscope with special attention to the part behind the capillary duct that in the previous examination had already yielded the most representative results (see Pictures n. 29).

Here again, the analysis of the walls reveals a clear on-going corrosion process, though less significant and widespread as against the tips of sample n. 1 (point a).

To obtain more accurate results, we also analysed the tip ink content already extracted at the washing stage.

The first microscopic observation showed that the ink mass was not homogeneous, but it had in it a gelatinous area which at a subsequent microscopic analysis (Picture n. 30) revealed the same physical structure detected in previous tests (see Picture n. 5).

We were able to set the constitution of this area thanks to the use of an EDS microprobe (Picture n. 31): the result points to the presence of copper and chlorine causing the gelling of ink.

The chlorine produced through an improper tip washing reacted with copper forming copper chloride. The latter reacts with ink carboxyl and generates carboxylates (metal soap). The final rheology is different from the original one and ink does not flow down smoothly in the duct.

To bear out this theoretical assumption the same analysis was carried out with ink of the same refill but taken from a different area, with no contact with the tip.

In this case the EDS test (see Picture n. 32) did not reveal the typical copper and chlorine peaks, meaning that the two elements are present only inside the tip and not in the original ink formulation.

d) Tips treated with hydrochloric acid (see Annex D sample 5).

To make sure that the root cause of all problems was really an acid etching of the tips produced during washing, we decided to reproduce the defect in the laboratory.

1 part of distilled water was mixed with 1 part of Methylene chloride previously extracted from the washing tank of a tip manufacturer.

The mixture thus obtained was shaken, and after the separation of the two solvents, water was used to dampen some good quality defect-free tips.

After 48 hours the tips of that lot were put directly under the electronic microscope to be observed.

Behind the capillary duct (Picture n. 33) you can already see the formation of saline efflorescence (whitish ramifications) which will react to the ink introduced into duct, leaving original sites empty and consequently forming hollow areas.

e) Non corroded X-10 tips (Annex D sample 6).

To obtain a further confirmation of this, a new test was performed with tips belonging to a lot of defect-free refills.

In this case there was no corrosion in the ball seat (Picture n.34), and even on the inner wall only rare corrosion sites are to be observed (Picture n.35).

– Corroded X-10 tips (see Annex D sample 7).

To confirm the presence or absence of oxidation in new tips, not yet filled with ink, the electronic microscope was used to observe new tips taken from lots with defective refills.

There are clear signs of corrosion and hollowness both in the ball seat (Picture n.36) and on the wall behind the capillary duct (Picture n.37). Please note the inappropriate machining of the ink feeding duct; it is obstructed and will not permit a normal ink flow.

There are already numerous crystalline formations of copper and zinc chlorides on the wall behind the inner duct, and if used to assemble refills they will react with ink.

Mr.Tinazzi closed his contribution showing to participants the above-mentioned pictures taken during recent tests.


Introduction to chlorinated solvents
(Beltramino -CIAT)

Mr.Beltramino, who has a twenty-years experience in this specific sector, was invited to the meeting as expert in chlorinated solvents.

He opened his speech with a quick explanation of the main characteristics of chlorinated solvents and how they are industrially obtained.

After a short introduction, he quickly moved to the specific use of these solvents, emphasising the need of their appropriate use – “though stabilised chlorinated solvents are highly unstable”.

It is very important to underline that chlorinated solvents, if correctly used and controlled, can yield exceptional results, if they are not properly used however, they can cause a lot of troubles.

The need was stressed to carry out regular checks of washing baths to prevent all the problems mentioned during this discussion.

To explain the remarkable strength of chlorinated solvents, reference was made to the borderline case of a plant manufacturing metal parts that had had serious corrosion problems because washing baths were very close to the production plant.

In that case it was enough to separate the washing department from the manufacturing one to sensitively limit the defect.

Mr.Beltramino moved then to illustrating the most well-known methods to control solvents and detect their acidity. Some of these methods have already been covered before.

The cleaning of the equipment is of paramount importance: the presence of brass powder in the bath may act as catalyst of the decomposition process and increase the acidity of the product.

The presence of oil in the washing bath proportionately increases the solvent boiling temperature. This require an increase in distillation temperature with a consequent greater risk of thermal decomposition.


Attentive use of chlorinated solvents and new washing methodologies
(Rosso – R.P.R. RIGHELLA)

When Mr.Beltramino ended his presentation, Mr.Rosso from R.P.R. (a company manufacturing tips for ball-point pens and refills of various kind), asked all participants to co-operate with Reinol in the future, so as to make it easier to perform tests and detect the cause of possible writing problems.

Mr.Rosso continued his speech asking Mr.Beltramino to explain the reason why such a serious defect has cropped up only very recently even though companies had been using the same working method fro twenty years.

Mr.Beltramino explained that the dismissal of the stabiliser known as 1,4-dioxan had, at least at first, increased the number of problems due to the corrosion of metal parts in every sector of the metal and steel industry.

In the past, the strong stabilisation power of 1,4-dioxan had counterbalanced the effects of inadequate washing.

At this point, Mr.Rosso reply asking for what reason the manufacturers of chlorinated solvents had not let the others know that this stabiliser had been replaced.

According to Mr.Beltramino, not only had these products been presented to all final users, but each manufacturer of chlorinated solvents tends now to emphasise the super-stability of hyper-stability of its solvents.

The owner of R.P.R. himself, who had been informed of the problem a few months before (he had taken part in the final stage of the tests together with Reinol), replaced the old solvent with another one, more suitable to that specific use and is still considering the use of special equipment to vacuum wash his tips (with this method the presence of steam is eliminated because the air re-entered in the machine is previously de-hydrated).


Importance of the equipment used for washing parts
(Claudio Nicol – DIPRO & Pagani – UNIVERSAL)

Thanks to a twenty-years experience in the field of washing machines using chlorinated solvents, Dr.Nicol could join to help the audience understand the issue better.

In his opinion, it is unthinkable that in certain companies the problems under study do not occur, since the use of chlorinated solvents is often inappropriate and the equipment, in most cases, unsuitable.

It is very important to update machines and equipments with necessary modifications, so as to limit as much as possible the thermal shock to which every solvent is subjected during heating stage.

He further recommended to avoid heating the solvent with heating elements that are the main cause of thermal decomposition.

to demonstrate this, he gave the example of washing machines for garments where the solvent was directly heated with heating elements. The latter became corroded and unusable in very short time. By contrast, heating carried out with steam coils, ensured a longer life of the equipment (even as long as ten years) manufactured in zinc-plated steel at the time.

Here again the pH control play a very important role.

Based on his personal experience, Dr.Nicol advised against the used of vacuum plants: results do not seem to live up to the expectations, especially with respect to separation at the aqueous stage.

This was also confirmed by Mr.Pagani of Universal. He also recommended to try and avoid the presence of water when working in total absence of thermal shocks.


Corrosion of machined but unwashed parts
(Christophe Dumusois – HAUSER)

The very interesting contribution by Mr.Dumusois stressed that Hauser too performed studies on the corrosion of roller tips.

The question was raised how can corrosion attack tips machined without using oil, unwashed and, what is more surprising, attack the un-machined part of the tip.

Mr.Buzzetti with the support of Mr.Rosso explained that over his latest visit to Boillat (manufacturer of brass bars), these problems had been touched upon. Apparently the manufacturers of brass themselves carry out the pickling of brass bars using chlorinated solvents (at the end of the extrusion process).

The reason why Mr.Dumusois observed corrosion in an un-machined part of the tip can be easily explained. In this case corrosion started at the brass bar manufacturing stage already.


Can the ink pH play an important role in corrosion?
(Mr.Santini – Premec)

At this point Mr.Santini raised a very interesting question: can the ink pH play an important role in corrosion?.

He pointed out that among German manufacturers there are two schools of thought in the formulation on ink fro ball-point pens: one prefers inks with an acid pH, the other a neutral or slightly alkaline pH.

Mr.Buzzetti replied that Reinol is familiar with both options and, in fact, it adopts both for the following reasons.

Many years ago tips were obtained from a brass tube by pressing. Brass used have a very high copper content, therefore inks with an acid pH were very good, whereas inks with a neutral or slightly alkaline pH had a limited shelf-life, a year approximately. In some cases neutral or alkaline inks yielded the best results, for instance when using tip manufactured in aluminium alloys.

Now both inks are being produced, but with corroded tips they raise the same problems.

Moreover the same defects have been registered in refills with ink formulated according to both theories.

Picture n. 25 – 26 – 27 – 28 – 29 – 30 – 31 – 32 –
33 – 34 – 35 – 36 – 37

Conclusion

At the end of the meeting Reinol stated that a number of customers showed interest in the setting up of a centralised laboratory specialised in research and study of these issues and in products quality control.

To meet this need, Reinol suggested to utilise an already existing structure with highly qualified personnel specialised in this sector and made its own laboratory available.

 

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