Ink

An ink is a liquid containing various pigments and/or dyes used for coloring a surface to produce an image or text. Ink is used for drawing or writing with a pen or brush or quill. Thicker inks, in paste form, are used extensively in letterpress and lithographic printing.

Ink is a complex medium, comprising solvents, pigments, dyes, resins, lubricants, solubilizers, particulate matter, fluorescers, and other materials. The components of inks serve many purposes; the ink’s carrier, colorants, and other additives are used to control flow, thickness, and appearance of the ink when dry.

Types of ink

Early varieties include Egyptian ink, various natural dyes made from metals, the husk or outer covering of beans or seeds, and sea creatures like the squid (known as sepia). India ink is black and originated in Asia. Iron gall ink was used by many of the old masters for drawing. Walnut ink is erroneously thought to have also been used by old masters, however, there is no proof of this. Walnut Inks, if they were used, would have faded fairly quickly and would therefore be unsuitable.

Pigmented inks

Pigmented inks contain other agents that ensure adhesion of the pigment to the surface and prevent it from being removed by mechanical abrasion. These materials are typically referred to as resins (in solvent-based inks) or binding agents (in water-based inks).

Pigmented inks are advantageous when printing on paper because the pigment stays on the surface of the paper. This is desirable because more ink on the surface means that less ink needs to be used to create the same intensity of color. Pigmented inks tend to be more resistant to washing out than dye-based inks. For this reason these inks are frequently recommended for applications where erasure is undesirable. Gel inks are particularly resistant to erasure and frequently bear recommendations from forgery experts.

Pigments are the main components of ink, containing the different colors. The size of the pigment is very important for the ability to diffuse in the solution inks. Qualities such as hue, saturation, and brightness or lightness are inherent in the ink, and vary dependent on the source and type of pigment.

Dyes in inks

Dye-based inks are generally much stronger than pigment-based inks and can produce much more color of a given density per unit of mass. However, because dyes are dissolved in the liquid phase, they have a tendency to soak into paper, thus making the ink less efficient and also potentially allowing the ink to bleed at the edges of an image, producing poor quality printing.

To circumvent this problem, dye-based inks are made with solvents that dry rapidly or are used with quick-drying methods of printing, such as blowing hot air on the fresh print. Other methods include harder paper sizing and more specialized paper coatings. The latter is particularly suited to inks used in non-industrial settings (which must conform to tighter toxicity and emission controls), such as inkjet printer inks. Another technique involves coating the paper with a charged coating. If the dye has the opposite charge, it is attracted to and retained by this coating, while the solvent soaks into the paper. Cellulose, the material that paper is made of, is naturally charged, and so a compound that complexes with both the dye and the paper's surface will aid retention at the surface. Such a compound in common use in ink-jet printing inks is polyvinyl pyrrolidone.

An additional advantage of dye-based ink systems is that the dye molecules interact chemically with other ink ingredients. This means that they can benefit more than pigmented ink from optical brighteners and color-enhancing agents designed to increase the intensity and appearance of dyes. Because dyes get their color from the interaction of electrons in their molecules, the way in which the electrons can move is determined by the charge and extent of electron delocalization in the other ink ingredients. The color emerges as a function of the light energy that falls on the dye. Thus, if an optical brightener or color enhancer absorbs light energy and emits it through or with the dye, the appearance changes, as the spectrum of light re-emitted to the observer changes.

A disadvantage of dye-based inks is that they can be more susceptible to fading, especially when exposed to ultraviolet radiation as in sunlight.

A more recent development in dye-based inks are dyes that react with cellulose to permanently color the paper. Such inks are not affected by water, alcohol, and other solvents. As such, their use is recommended to prevent frauds that involve removing signatures, such as check washing. Currently this kind of ink is most often offered for use in fountain pens. The most popular manufacturer of this ink is Noodler.

History of ink

Approximately 5000 years ago, an ink for blacking the raised surfaces of pictures and texts carved in stone was developed in China. This early ink was a mixture of soot from pine smoke, lamp oil, and gelatin from animal skins and musk. Other early cultures also developed many colors of ink from available berries, plants and minerals.

In an article for the Christian Science Monitor, Sharon J. Huntington describes these other historical inks:

About 1,600 years ago, a popular ink recipe was created. The recipe was used for centuries. Iron "salts," such as ferrous sulfate (made by treating iron with sulfuric acid), was mixed with tannin from gallnuts (they grow on trees) and a thickener. When first put to paper, this ink is bluish-black. Over time it fades to a dull brown.

Scribes in medieval Europe (about AD 800 to 1500) wrote on sheepskin parchment. One 12^th century ink recipe called for hawthorn branches to be cut in the spring and left to dry. Then the bark was pounded from the branches and soaked in water for eight days. The water was boiled until it thickened and turned black. Wine was added during boiling. The ink was poured into special bags and hung in the sun. Once dried, the mixture was mixed with wine and iron salt over a fire to make the final ink.

In the 15^th century, a new type of ink had to be developed in Europe for the printing press by Johannes Gutenberg. Two types of ink were prevalent at the time: the Greek and Roman writing ink (soot, glue, and water) and the 12^th century variety composed of ferrous sulfate, gall, gum, and water.^[1] Neither of these handwriting inks could adhere to printing surfaces without creating blurs. Eventually an oily, varnish-like ink made of soot, turpentine, and walnut oil was created specifically for the printing press.

Modern ink applications

Up until a few years ago, consumers had very little interest in ink other than refills for their pens. Fountain pens became a novelty as the disposable ball point pen took over the market. The introduction of home computing led to home printing. Today, in developed nations, it is rare to find a residence or a business that does not have a printing capability. As a result, buying ink in the form of a cartridge has once again become a part of the day-to-day shopping experience, similar to buying a bottle of ink fifty years ago.

Ink refilling services for printer cartridges are offered by large, official printing companies as well as smaller, "unofficial" refill companies. Customers can often cut printing costs by using refill services from a refill company, or buying the new non-OEM brands instead of refilling.

Health aspect

There is a misconception that ink isn't harmful even if swallowed, but this is false. Once ingested, ink can be very hazardous to one's health. Certain inks, such as those used in printers, and even those found in a common pen can be harmful. Though ink will not cause death, it can cause side effects such as a damaged nervous system and severe headaches. These effects are caused by a chemical known as p-Anisidine, used in the process of creating the ink's color and shine. The poison control center has stated that any consumption of ink should be reported to a local hospital or poison control center.

Writing Inks and Preservation

The two most used black writing inks in history are carbon inks and iron gall inks. Both types create problems for preservationists.

Carbon Inks

Carbon inks were commonly made from lampblack or soot and gum arabic. Gum arabic keeps the carbon particles in suspension and adhered to paper. The carbon particles do not fade over time even when in sunlight or bleached. One benefit of carbon ink is that it is not harmful to the paper. Over time, the ink is chemically stable and therefore does not threaten the strength of the paper. Despite these benefits, carbon ink is not the ideal ink for permanence and ease of preservation. The ink has a tendency to smudge in humid environments and can be washed off an item. The best method of preserving documents written in carbon ink is to ensure it is stored in a dry environment (Barrow 1972). Recently, carbon inks made from carbon nanotubes have been successfully created. They are similar in composition to the traditional inks in that they use a polymer to suspend the carbon nanotubes. These inks can be used in inkjet printers and produce electrically conductive patterns.^[2]

Iron Gall Inks

Iron gall inks became prominent in the early 1100's and were used for centuries and thought to be the best type of ink. However, iron gall ink is corrosive and damages the paper it is on (Waters 1940). Items containing this ink can become brittle and the writing fades to brown. The original scores of Johann Sebastian Bach are threatened by the destructive properties of iron gall ink. The majority of his works are held by the German State Library, and about 25% of those are in advanced stages of decay (American Libraries 2000). The rate at which the writing fades is based on several factors, such as "the proportions of the ink ingredients, the amount deposited on the paper, and the composition of the paper" (Barrow 1972:16). The corrosion is caused by "two major degradation processes: acid catalysed hydrolysis and iron(II)-catalysed oxidation of cellulose" (Rouchon-Quillet 2004:389).

Treatment is a controversial subject. There is no treatment that will undo the damage already caused by the acidic ink. Deterioration can only be stopped or slowed for a period of time. There are some people who think it best not to treat the item at all for fear of the consequences. Others believe that non-aqueous procedures are the best solution. And then, there are some that believe an aqueous procedure may provide the answer for preserving items written with iron gall ink. Aqueous treatments include distilled water at different temperatures, calcium hydroxide, calcium bicarbonate, magnesium carbonate, magnesium bicarbonate, and calcium phytate. There are many possible side effects from these treatments. There can be mechanical damage, which would further weaken the paper. The color of the paper or ink may change and ink may bleed. Other consequences that might arise from aqueous treatment are a change of ink texture or the formation of on the surface of the ink (Reibland & de Groot 1999).

Iron gall inks are generally stored in a stable environment, because fluctuating relative humidity increases the rate at which formic acid, acetic acid and furan derivatives form in the material on which the ink was used. Sulfuric acid acts as a catalyst to cellulose hydrolysis, and iron (II) sulfate acts as a catalyst to cellulose oxidation. These chemical reactions physically weaken the paper, causing brittleness.^[3]

Sources

N.a. (March 2000), "Bach Scores Turning to Dust in German Library", American Libraries: 24–25
Barrow, W.J. (1972), Manuscripts and Documents: Their Deterioration and Restoration, Charlottesville: University Press of Virginia, ISBN 081390408 {{citation}}: Check |isbn= value: length (help)
Reibland, Birgit; de Groot, Suzan (August 15–21, 1999), "Ink Corrosion: Comparison of the Currently Used Aqueous Treatments for Paper Objects", Preprint from the 9th International Congress of IADA, p. 121-129{{citation}}: CS1 maint: date format (link)
Rouchon-Quillet, V.; et al. (2004), "The Impact of Gallic Acid on Iron Gall Ink Corrosion", Applied Physics A, 79: 389–392 {{citation}}: Explicit use of et al. in: |last2= (help)
Waters, C.E. (1940), Inks, U.S. Department of Commerce, National Bureau of Standards, U.S. Government Printing Office {{citation}}: Text "Circular C426" ignored (help)

Footnotes

^ Many recipes for iron gall inks are featured in A booke of secrets: shewing diuers waies to make and prepare all sorts of inke... tr. out of Dutch into Englishe by W.P. [i.e. William Philip], London, 1596.
^ Simmons, Trevor (2007). "Large Area-Aligned Arrays from Direct Deposition of Single-Wall Carbon Nanotubes". J. Am. Chem. Soc. 129 (33): 10088–10089.
^ Henk J. Porck and René Teygeler, Preservation Science Survey (Washington, D.C.: Council on Library and Information Resources, 2000).

References

"Think Ink!" by Sharon J. Huntington, Christian Science Monitor, September 21, 2004, retrieved January 17, 2006.
"A History of Technology and Invention" by Maurice Audin, page 630.
Ainsworth, Mitchell, C., "Inks and Their Composition and Manufacture," Charles Griffin and Company Ltd, 1904.
Martín-Gil J, Ramos-Sánchez MC, Martín-Gil FJ and José-Yacamán M. "Chemical composition of a fountain pen ink". Journal of Chemical Education, 2006, 83, 1476-78

External links

[1] Many recipes for iron gall inks are featured in A booke of secrets: shewing diuers waies to make and prepare all sorts of inke... tr. out of Dutch into Englishe by W.P. [i.e. William Philip], London, 1596.

[2] Simmons, Trevor (2007). "Large Area-Aligned Arrays from Direct Deposition of Single-Wall Carbon Nanotubes". J. Am. Chem. Soc. 129 (33): 10088–10089.

[3] Henk J. Porck and René Teygeler, Preservation Science Survey (Washington, D.C.: Council on Library and Information Resources, 2000).

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Ink