Ink is a

gel A gel is a semi-solid that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady-state, although the liquid phase may still di ...

sol Sol or SOL may refer to: Astronomy * The Sun Currency * SOL Project, a currency project in France * French sol, or sou * Argentine sol * Bolivian sol, the currency of Bolivia from 1827 to 1864 * Peruvian sol, introduced in 1991 * Peruvian sol ( ...

, or

solution Solution may refer to: * Solution (chemistry), a mixture where one substance is dissolved in another * Solution (equation), in mathematics ** Numerical solution, in numerical analysis, approximate solutions within specified error bounds * Soluti ...

that contains at least one colorant, such as a

dye A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution an ...

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compo ...

, and is used to color a surface to produce an

image An image is a visual representation of something. It can be two-dimensional, three-dimensional, or somehow otherwise feed into the visual system to convey information. An image can be an artifact, such as a photograph or other two-dimensiona ...

, text, or

design A design is a plan or specification for the construction of an object or system or for the implementation of an activity or process or the result of that plan or specification in the form of a prototype, product, or process. The verb ''to design'' ...

. Ink is used for

drawing Drawing is a form of visual art in which an artist uses instruments to mark paper or other two-dimensional surface. Drawing instruments include graphite pencils, pen and ink, various kinds of paints, inked brushes, colored pencils, crayons, ...

writing Writing is a medium of human communication which involves the representation of a language through a system of physically Epigraphy, inscribed, Printing press, mechanically transferred, or Word processor, digitally represented Symbols (semiot ...

with a pen,

brush A brush is a common tool with bristles, wire or other filaments. It generally consists of a handle or block to which filaments are affixed in either a parallel or perpendicular orientation, depending on the way the brush is to be gripped durin ...

, reed pen, or

quill A quill is a writing tool made from a moulted flight feather (preferably a primary wing-feather) of a large bird. Quills were used for writing with ink before the invention of the dip pen, the metal- nibbed pen, the fountain pen, and, eventually ...

. Thicker inks, in paste form, are used extensively in letterpress and lithographic

printing Printing is a process for mass reproducing text and images using a master form or template. The earliest non-paper products involving printing include cylinder seals and objects such as the Cyrus Cylinder and the Cylinders of Nabonidus. The ea ...

. Ink can be a complex medium, composed of

solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...

s, pigments,

resin In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on natu ...

lubricant A lubricant (sometimes shortened to lube) is a substance that helps to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces, t ...

solubilizer Micellar solubilization (solubilization) is the process of incorporating the solubilizate (the component that undergoes solublization) into or onto micelles. Solublization may occur in a system consisting of a solvent, an association colloid (a co ...

surfactant Surfactants are chemical compounds that decrease the surface tension between two liquids, between a gas and a liquid, or interfacial tension between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming ...

particulate matter Particulates – also known as atmospheric aerosol particles, atmospheric particulate matter, particulate matter (PM) or suspended particulate matter (SPM) – are microscopic particles of solid or liquid matter suspended in the air. The ter ...

, fluorescents, and other materials. The components of inks serve many purposes; the ink's carrier, colorants, and other additives affect the flow and thickness of the ink and its dry appearance. In 2011, worldwide consumption of printing inks generated revenues of more than 20 billion US dollars. While demand by traditional print media (including newspapers) is shrinking; more and more printing inks are consumed for packaging.

History

Many ancient cultures around the world have independently discovered and formulated inks for the purposes of writing and drawing. The knowledge of the inks, their recipes and the techniques for their production comes from archaeological analysis or from written text itself. The earliest inks from all civilizations are believed to have been made with '' lampblack'', a kind of soot, as this would have been easily collected as a by-product of fire. Ink was used in Ancient Egypt for writing and drawing on

papyrus Papyrus ( ) is a material similar to thick paper that was used in ancient times as a writing surface. It was made from the pith of the papyrus plant, '' Cyperus papyrus'', a wetland sedge. ''Papyrus'' (plural: ''papyri'') can also refer to a ...

from at least the 26th century BC. Egyptian red and black inks included

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...

and

ocher Ochre ( ; , ), or ocher in American English, is a natural clay earth pigment, a mixture of ferric oxide and varying amounts of clay and sand. It ranges in colour from yellow to deep orange or brown. It is also the name of the colours produced ...

as a pigment, in addition to

phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phospho ...

, sulfate,

chloride The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the element chlorine (a halogen) gains an electron or when a compound such as hydrogen chloride is dissolved in water or other polar solvents. Chloride salts ...

, and carboxylate ions; meanwhile,

lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...

was used as a drier. Chinese inks may go back as far as four millennia, to the Chinese Neolithic Period. These used plants, animal, and mineral inks based on such materials as

graphite Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large ...

that were ground with water and applied with

ink brush Ink is a gel, sol, or solution that contains at least one colorant, such as a dye or pigment, and is used to color a surface to produce an image, text, or design. Ink is used for drawing or writing with a pen, brush, reed pen, or quill. Thicke ...

es. Direct evidence for the earliest Chinese inks, similar to modern inksticks, is around 256 BC in the end of the

Warring States period The Warring States period () was an era in History of China#Ancient China, ancient Chinese history characterized by warfare, as well as bureaucratic and military reforms and consolidation. It followed the Spring and Autumn period and concluded ...

and produced from soot and animal glue. The best inks for drawing or painting on paper or silk are produced from the resin of the pine tree. They must be between 50 and 100 years old. The Chinese inkstick is produced with a fish glue, whereas Japanese glue (膠 ''nikawa'') is from cow or stag. India ink was invented in China,Smith, Joseph A. (1992). ''The Pen and Ink Book: Materials and Techniques for Today's Artist''.p. 23. New York: Watson-Guptill Publications. . though materials were often traded from India, hence the name.Gottsegen, Mark D. (2006). ''The Painter's Handbook: A Complete Reference''.Page 30, New York: Watson-Guptill Publications. . The traditional Chinese method of making the ink was to grind a mixture of hide glue, carbon black, lampblack, and bone black pigment with a

pestle and mortar Mortar and pestle is a set of two simple tools used from the Stone Age to the present day to prepare ingredients or substances by crushing and grinding them into a fine paste or powder in the kitchen, laboratory, and pharmacy. The ''mortar'' () ...

, then pour it into a ceramic dish to dry. To use the dry mixture, a wet brush would be applied until it reliquified. The manufacture of India ink was well-established by the

Cao Wei Wei ( Hanzi: 魏; pinyin: ''Wèi'' <

Middle Chinese

: *''ŋjwei^C'' <

dynasty (220–265 AD). Indian documents written in

Kharosthi The Kharoṣṭhī script, also spelled Kharoshthi (Kharosthi: ), was an ancient Indo-Iranian script used by various Aryan peoples in north-western regions of the Indian subcontinent, more precisely around present-day northern Pakistan and ...

with ink have been unearthed in Chinese Turkestan. The practice of writing with ink and a sharp pointed needle was common in early South India. Several

Buddhist Buddhism ( , ), also known as Buddha Dharma and Dharmavinaya (), is an Indian religion or philosophical tradition based on teachings attributed to the Buddha. It originated in northern India as a -movement in the 5th century BCE, and ...

and Jain sutras in India were compiled in ink. In

ancient Rome In modern historiography, ancient Rome refers to Roman civilisation from the founding of the city of Rome in the 8th century BC to the collapse of the Western Roman Empire in the 5th century AD. It encompasses the Roman Kingdom (753–509 B ...

atramentum Atramentum or atrament, generally means a very black, usually liquid, substance. For example, an octopus may emit a puff of atrament (see cephalopod ink). In ancient Rome, the term ''atramentum'' signified any black colouring substance used for a ...

was used; in an article for the '' Christian Science Monitor'', Sharon J. Huntington describes these other historical inks: Oak galls and iron(II) sulfate - California State Archives

Oak galls and iron(II) sulfate - California State Archives

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), were mixed with tannin from
gall Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths of plant tissues, similar to be ...
nuts (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 In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the Post-classical, post-classical period of World history (field), global history. It began with t ...
Europe (about AD 800 to 1500) wrote principally on
parchment Parchment is a writing material made from specially prepared untanned skins of animals—primarily sheep, calves, and goats. It has been used as a writing medium for over two millennia. Vellum is a finer quality parchment made from the skins of ...
or
vellum Vellum is prepared animal skin or membrane, typically used as writing material. Parchment is another term for this material, from which vellum is sometimes distinguished, when it is made from calfskin, as opposed to that made from other anima ...
. One 12th 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.

The reservoir pen, which may have been the first

fountain pen A fountain pen is a writing instrument which uses a metal nib to apply a water-based ink to paper. It is distinguished from earlier dip pens by using an internal reservoir to hold ink, eliminating the need to repeatedly dip the pen in an inkw ...

, dates back to 953, when Ma'ād al-Mu'izz, the

caliph A caliphate or khilāfah ( ar, خِلَافَة, ) is an institution or public office under the leadership of an Islamic steward with the title of caliph (; ar, خَلِيفَة , ), a person considered a political-religious successor to th ...

of Egypt, demanded a pen that would not stain his hands or clothes, and was provided with a pen that held ink in a reservoir. In the 15th century, a new type of ink had to be developed in Europe for the

printing press A printing press is a mechanical device for applying pressure to an inked surface resting upon a printing, print medium (such as paper or cloth), thereby transferring the ink. It marked a dramatic improvement on earlier printing methods in wh ...

Johannes Gutenberg Johannes Gensfleisch zur Laden zum Gutenberg (; – 3 February 1468) was a German inventor and Artisan, craftsman who introduced letterpress printing to Europe with his movable type, movable-type printing press. Though not the first of its ki ...

. According to Martyn Lyons in his book ''Books: A Living History'', Gutenberg's dye was indelible, oil-based, and made from the soot of lamps (lamp-black) mixed with

varnish Varnish is a clear transparent hard protective coating or film. It is not a stain. It usually has a yellowish shade from the manufacturing process and materials used, but it may also be pigmented as desired, and is sold commercially in various ...

and egg white. Two types of ink were prevalent at the time: the Greek and Roman writing ink (soot, glue, and water) and the 12th century variety composed of ferrous sulfate, gall, gum, and water. Neither of these handwriting inks could adhere to printing surfaces without creating blurs. Eventually an oily,

-like ink made of soot,

turpentine Turpentine (which is also called spirit of turpentine, oil of turpentine, terebenthene, terebinthine and (colloquially) turps) is a fluid obtained by the distillation of resin harvested from living trees, mainly pines. Mainly used as a special ...

, and walnut oil was created specifically for the printing press.

Types

Ink formulas vary, but commonly involve two components: * Colorants * Vehicles (binders) Inks generally fall into four classes: * Aqueous * Liquid * Paste * Powder

Colorants

Pigments

Pigment inks are used more frequently than dyes because they are more color-fast, but they are also more expensive, less consistent in color, and have less of a color range than dyes. Pigments are solid, opaque particles suspended in ink to provide color. Pigment molecules typically link together in

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

line structures that are 0.1–2

µm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

in size and comprise 5–30 percent of the ink volume. Qualities such as hue, saturation, and

lightness Lightness is a visual perception of the luminance (L) of an object. It is often judged relative to a similarly lit object. In colorimetry and color appearance models, lightness is a prediction of how an illuminated color will appear to a stan ...

vary depending on the source and type of pigment.

Dyes

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, potentially allowing the ink to bleed at the edges of an image. 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 Sizing or size is a substance that is applied to, or incorporated into, other materials—especially papers and textiles—to act as a protective filler or glaze. Sizing is used in papermaking and textile manufacturing to change the absorption ...

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 Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...

, the wood-derived material most paper is made of, is naturally charged, and so a compound that complexes with both the dye and the paper's surface aids retention at the surface. Such a compound is commonly used in ink-jet printing inks. An additional advantage of dye-based ink systems is that the dye

molecule A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioch ...

s can interact with other ink ingredients, potentially allowing greater benefit as compared to pigmented inks from

optical brightener Optical brighteners, optical brightening agents (OBAs), fluorescent brightening agents (FBAs), or fluorescent whitening agents (FWAs), are chemical compounds that absorb light in the ultraviolet and violet region (usually 340-370 nm) of the ...

s and color-enhancing agents designed to increase the intensity and appearance of dyes. Dye-based inks can be used for anti-counterfeit purposes and can be found in some gel inks, fountain pen inks, and inks used for paper currency. These inks react with cellulose to bring about a permanent color change.

Health and environmental aspects

There is a misconception that ink is non-toxic even if swallowed. Once ingested, ink can be hazardous to one's health. Certain inks, such as those used in digital printers, and even those found in a common pen can be harmful. Though ink does not easily cause death, repeated skin contact or ingestion can cause effects such as severe headaches, skin irritation, or nervous system damage. These effects can be caused by solvents, or by pigment ingredients such as ''p''-Anisidine, which helps create some inks' color and shine. Three main environmental issues with ink are: *

Heavy metals upright=1.2, Crystals of osmium, a heavy metal nearly twice as dense as lead">lead.html" ;"title="osmium, a heavy metal nearly twice as dense as lead">osmium, a heavy metal nearly twice as dense as lead Heavy metals are generally defined as ...

Eisengallustinte selbstgemacht schriftbild

* Non-renewable oils *

Volatile organic compound Volatile organic compounds (VOCs) are organic compounds that have a high vapour pressure at room temperature. High vapor pressure correlates with a low boiling point, which relates to the number of the sample's molecules in the surrounding air, a ...

s Some regulatory bodies have set standards for the amount of heavy metals in ink. There is a trend toward vegetable oils rather than

petroleum oil Mineral oil is any of various colorless, odorless, light mixtures of higher alkanes from a mineral source, particularly a distillate of petroleum, as distinct from usually edible vegetable oils. The name 'mineral oil' by itself is imprecise, ...

s in recent years in response to a demand for better environmental sustainability performance. Ink uses up non-renewable oils and metals, which has a negative impact on the environment.

Carbon

Carbon inks were commonly made from lampblack or soot and a binding agent such as gum arabic or animal glue. The binding agent keeps carbon particles in suspension and adhered to paper. Carbon particles do not fade over time even when bleached or when in sunlight. One benefit is that carbon ink does not harm paper. Over time, the ink is chemically stable and therefore does not threaten the paper's strength. Despite these benefits, carbon ink is not ideal for permanence and ease of preservation. Carbon ink tends to smudge in humid environments and can be washed off surfaces. The best method of preserving a document written in carbon ink is to store it in a dry environment (Barrow 1972). Recently, carbon inks made from carbon nanotubes have been successfully created. They are similar in composition to 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.

Iron gall (common ink)

Iron gall inks became prominent in the early 12th century; they were used for centuries and were widely thought to be the best type of ink. However, iron gall ink is corrosive and damages paper over time (Waters 1940). Items containing this ink can become brittle and the writing fades to brown. The original scores of

Johann Sebastian Bach Johann Sebastian Bach (28 July 1750) was a German composer and musician of the late Baroque period. He is known for his orchestral music such as the '' Brandenburg Concertos''; instrumental compositions such as the Cello Suites; keyboard w ...

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 proportions of ink ingredients, amount deposited on the paper, and paper composition (Barrow 1972:16). Corrosion is caused by acid catalysed hydrolysis and iron(II)-catalysed oxidation of cellulose (Rouchon-Quillet 2004:389). Treatment is a controversial subject. No treatment undoes damage already caused by acidic ink. Deterioration can only be stopped or slowed. Some 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. Yet others think an aqueous procedure may preserve 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 further weakens the paper. Paper color or ink color may change, and ink may bleed. Other consequences of aqueous treatment are a change of ink texture or formation of plaque on the surface of the ink (Reibland & de Groot 1999). Iron gall inks require storage in a stable environment, because fluctuating

relative humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity depe ...

increases the rate that formic acid, acetic acid, and furan derivatives form in the material the ink was used on. 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 A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. Bre ...

Indelible ink

''Indelible'' means "unremovable". Some types of indelible ink have a very short shelf life because of the quickly evaporating solvents used. India, Mexico, Indonesia, Malaysia and other developing countries have used indelible ink in the form of electoral stain to prevent

electoral fraud Electoral fraud, sometimes referred to as election manipulation, voter fraud or vote rigging, involves illegal interference with the process of an election, either by increasing the vote share of a favored candidate, depressing the vote share of ...

. Election ink based on

silver nitrate Silver nitrate is an inorganic compound with chemical formula . It is a versatile precursor to many other silver compounds, such as those used in photography. It is far less sensitive to light than the halides. It was once called ''lunar caustic' ...

was first applied in the

1962 Indian general election General elections were held in India between 19 and 25 February 1962 to elect members of the 3rd Lok Sabha. Unlike the previous two elections, each constituency elected a single member. Jawaharlal Nehru won another landslide victory in his th ...

, after being developed at the National Physical Laboratory of India. The election commission in India has used indelible ink for many elections. Indonesia used it in its last election in

Aceh Aceh ( ), officially the Aceh Province ( ace, Nanggroë Acèh; id, Provinsi Aceh) is the westernmost province of Indonesia. It is located on the northernmost of Sumatra island, with Banda Aceh being its capital and largest city. Granted a s ...

. In Mali, the ink is applied to the fingernail. Indelible ink itself is not infallible as it can be used to commit electoral

fraud In law, fraud is intentional deception to secure unfair or unlawful gain, or to deprive a victim of a legal right. Fraud can violate civil law (e.g., a fraud victim may sue the fraud perpetrator to avoid the fraud or recover monetary compens ...

by marking opponent party members before they have chances to cast their votes. There are also reports of "indelible" ink washing off voters' fingers in Afghanistan.Afghanistan election: 'indelible' ink washes off voters' fingers
/ref>

References

Sources

* Ainsworth, Mitchell, C., "Inks and Their Composition and Manufacture," Charles Griffin and Company Ltd, 1904. * * Banerji, Sures Chandra (1989). ''A Companion to Sanskrit Literature''. Motilal Banarsidass. . * * 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. * * * Sircar, D. C. (1996).''Indian epigraphy''. Motilal Banarsidass. . *

External links

Forty Centuries of Ink (David N. Carvalho); A detailed online textbook

* ttp://www.djmcadam.com/ink-recipe.html Ancient and Modern Ink Recipes (David N. Carvalho)
Gorgeous Portrayal Of How Ink Is Made
– video at ''

The Huffington Post ''HuffPost'' (formerly ''The Huffington Post'' until 2017 and sometimes abbreviated ''HuffPo'') is an American progressive news website, with localized and international editions. The site offers news, satire, blogs, and original content, and ...

''
"A Light Note on the Science of Writing and Inks"
is a manuscript, in Arabic, from 1852. It discusses the process of making inks. {{Authority control Printing materials