Basically inks are aqueous, liquid, paste or powder, and consist of colour, binder, additive and carrier. However, they can also be composed of solvents, pigments, dyes, resins, lubricants, solubilizers, surfactants, particulate matter, fluorescers, waxes, drying agents and other substances.

Inks are made from pigments and dyes which can be of animal origin like insects, molluscs, octopuses, chameleons and snails. Pigments or colours derived from animal or plant cells are called biological or organic pigments, whereas in the case of dyes they are termed natural dyes. Therefore, biological and organic pigments, as well as natural dyes used to make inks, can very well be of animal origin.

Gel ink is of high viscosity or thickness and the pigments are typically copper phthalocyanine and iron oxides, and the gel is made up on water and biopolymers such as xanthan gum and tragacanth gum, as well as some types of polyacrylate thickeners.

Ballpoint pens use a paste ink based on a dye solute in an alcohol solvent. Particles of carbon black and/or titanium dioxide (black and white mineral origin pigments) are segregated from each other by a polymer that is absorbed and then the solvent is applied to make the ink flow.

Fountain pens and liquid-ink roller-ball pens use a dye solute in a water-based solvent. The ink could be a combination of tannic, gallic and dilute hydrochloric acid with an iron salt, phenol, and a blue or black dye. Also include a drying agent, an adhesion promoter, a colour developer and/or a preservative.

Some inks are made thicker, such as printing ink.

Most ink cartridges used for printers do not contain any animal derived products or use animal substances during the manufacturing process. But, some amount of animal testing on new ink components and to classify for waste is carried out as admitted by the Hewlett-Packard Company.

Highlighter pens or markers use an oil-based ink that is very opaque and overlays colours beneath it. A typical translucent highlighter is fluorescent yellow having been coloured with pyranine, a water soluble chemical dye. (Yellow is popular because it does not produce a shadow when Xeroxing. Other colours, including black used to hide information, are made.)

Correction pens and fluid consists of opaque, white substances used to mask text. Upon application they evaporate fast into the air which we breathe, and are similar to nail polish remover. Some such VOCs (volatile organic compounds) used are dangerous to human health and harmful to the environment. To avoid their misuse, mainly by teenagers as cheap intoxicating inhalants, India banned the retail sale of bottled correction fluid and nail polish remover, but allows its sale in devices that dispense small controlled amounts. So now correction fluids without chemical solvents (they take longer to dry and two coats may be needed) are available.

Felt-tip pens used to contain strong smelling VOCs like toluene and xylene solvents but now the ink is made on the basis of alcohols. The ink in permanent markers that write on glass, plastic, wood, metal and stone, lasts for years contain VOCs.

Invisible or disappearing ink is used with a decoder pen for children to play with. The ink is also used as security ink or for espionage. Some are developed by heat and work like litmus paper; others by chemical reaction and glow bright under UV light. The former could contain animal origin fluids like blood serum or ingredients such as honey, wine and milk – even colas, soap water, sugar, lemon, and other juices could be used.

The binder in India/black indelible ink is shellac. A unique violet indelible ink used to mark the voters’ fingers (it turns black on drying) made for the Election Commission of India is a mix of shellac, dyes, chemicals, aromatic material, biocide and silver nitrate (7-25%). Manufactured by the Mysore Paints and Varnish Ltd (earlier known as Mysore Lac and Paints) the formula is a closely guarded secret. They export this India indelible ink to more than 60 nations.

Scale insects lac, cochineal and kermes, produce dyes in shades of red, but shellac is used in India ink as a binder to make it more durable once dried.

In 2014, for the 16th Lok Sabha elections, the company supplied 21,65,000 litres of indelible ink. Vials of 5 ml are considered enough for 350 voters, and 7.5 ml vials for 450 voters. 2006 onwards the ink has been applied from the top end of the left forefinger nail to the bottom of the first joint. Earlier, it was applied to the joint between nail and skin.

The company also exports this ink for voting to Sierra Leone, Ghana, Turkey, Afghanistan, Pakistan, Nepal, Denmark, South Africa, Malaysia, UK, Fiji and the Republic of Benin.

Interestingly, India ink called masi in the 4th Century BC was made of burnt bones, blood, tar, pitch and soot. Today, tattoo ink could contain similar ingredients, or be made from iron oxides, metal salts and plastics.

Tyrian or imperial purple dye is obtained from bodies of certain molluscs and royal blue from snails. Melanin is ink from the octopus and sepia of any cephalopod. They are in shades of red to dark brown. Sepia is made from the ink sacs of cuttlefish which are dried and ground to a fine powder, and then mixed with shellac. True sepia ink as it is called, is still available and is used by some artists.

Walnut juice was used to make walnut ink which Rembrandt, Leonardo and Rubens are said to have used for some of their sketches. Since the clear milky juice of walnuts turns dark when it is exposed to air, in Ancient Rome it was also combined with leeches, ashes and charred things to make dark hair dye.

A lake pigment is manufactured by precipitating an inert binder or mordant, usually a metallic salt. Lake pigments such as carmine lake was originally produced from the cochineal insect.

It is possible to produce botanical natural colours red from beetroot, tomatoes, annatto-seed and pomegranate, pink from raspberry, orange from oranges, paprika and orange carrots, purple from blueberry, ube, acai and purple carrots, yellow from gardenia fruit, saffron, marigold and turmeric, green from alfalfa, chlorophyll, matcha, spinach and parsley, blue from spirulina and purple/red cabbage, brown from coffee, cocoa and cinnamon, black from activated charcoal, and black cocoa. However, these are basically used for food colours, not the sources used by paint manufacturers in India. Worse still, they sell pony hair brushes as well as natural and white bristle (hog/pig hair) artists’ brushes.