Paints

Azo Dyes are artificial colourings synthesized from petroleum however other dyes could be of animal origin. Chitin from shrimps and crabs could be used as a dyeing assistant. A reddish dye called Tyrian/royal/imperial purple or imperial dye is obtained from the bodies of certain molluscs; another purple-blue indigo dye hyacinth purple/royal blue was derived from Phoenician sea snails. Dyes from insects like lac, cochineal and kermes are all in shades of red. Cochineal is used as crimson lake or pink, and charred ivory as ivory black in artists’ paints. This, despite the fact, that every plant can produce a dye, e.g. red from pomegranate and brown from barks.

Bone black (alternate names: animal black, animal charcoal, bone char, bone charcoal, drop black, ivory black Franfort black, German black, Paris black and ossa sepiae) is obtained from charring ground animal bones, mainly cattle and pigs. It is often labelled as an inorganic pigment because it consists of hydroxyapatite, calcium carbonate and carbon, all considered inorganic substances. Hydroxyapatite is also known as bone mineral since it naturally occurs from calcium apatite.

The following 4 paras are reproduced from the Natural Pigments website:

Bone black is animal charcoal prepared from bones, which have been exposed to high temperatures (550°C) without access of air. The bones are roasted in closed vessels. The residue of the ignition is a black matter, which when reduced to powder, forms bone black, sometimes incorrectly called ivory black. Ivory by carbonization will furnish a black, which, on account of its fineness and intensely black colour, is more esteemed than the ordinary bone black, but it is much more expensive and largely unavailable today.

In manufacturing bone black, the bones are first boiled in water or a solvent to remove the fat and then subjected to destructive distillation in closed containers, vented to remove the ammonia, called bone-spirit, together with a dark tarry liquid (bone-oil). When the bones cease to release vapours, the residue is charred bone or bone black. Bone consists of protein collagen with inorganic matter. As a result of the decomposition of the animal matter in this destructive distillation, the nitrogen and hydrogen, united as ammonia, and a part of the charcoal, in the form of carbonic acid gas, distilled over, while the remainder of the charcoal is left in the closed containers.

Carbon pigments formed by the pyrolysis of animal matter, such as ivory black and bone black, fall within the category of cokes as the protein collagen soften or liquefies before charring. Cokes are defined as a carbonized matter from a precursor in a liquid or plastic state. They thus do not show evidence of their former structure but rather from irregular, porous lumps. Ivory and bone contain a high percentage of inorganic matter, elephant ivory about 55%. The inorganic material, mostly as hydroxyapatite Ca5(OH) (PO4)3.


Maximilian Toch (an American paint manufacturer and industrial chemist) describes how ivory black differs from bone black, “Ivory black is prepared from charred ivory, and contains only about 20% of carbon black, the balance of it being phosphate of lime or bone material, but it is unlike any other black, on account of its intensity.” Today, ivory black is no longer made in commercial amounts so that pigments and paints named ivory black do not contain charred ivory but rather are a fine particle size grade of bone black with high carbon content.

Some black paints could also contain fatty acid pitch, a by-product residue of the soap industry. Lamp black (soot from oil lamps), and carbon black (petroleum/mineral origin) pigments in black colour are also available.

Tempera is a painting medium in which pigment is mixed with egg; similarly gouache is watercolour thickened with gum. Oil pastels contain animal fat. Wax crayons contain beeswax and possibly shellac. Animals are used for testing crayons etc., e.g. Camlin.

The key raw materials used by the wall painting industry are pigments, binders, solvents and additives. Titanium dioxide is widely used, and other raw materials like phthalic anhydride, pentaerythritol, methyl methacrylate, aromatics, etc. which act like binders, solvents and additives are derivatives of crude oil distillate. And since 75% of paints consist of binders, solvents and additives, three-fourths of the raw materials are derived from major distillates of crude oil. However, there are as many as 300 raw materials used by the paint industry.

Pigment is a substance such as chlorophyll (plant) or melanin (found in skin, hair, fur, and feathers) that produces a characteristic colour in plant or animal tissues. White pigment (not choona of shell origin) is titanium dioxide and black pigment carbon black (both mineral). Other mineral pigments used to make paint include iron oxide and cadmium sulphide for reds, metallic salts for yellows and oranges, and iron blue and chrome yellow for blues and greens. Shellac (animal origin) pigmented with white titanium dioxide is widely used by painters as stain sealer, wall board primer and knot and sap sealer on wood. Liquid lac that imparts desired levels of sheen is painted on wooden and metal pieces as a finisher. The lacquer may be clear/transparent or with colour added – it dries by solvent evaporation or a curing process that produces a hard, durable, protective finish. In comparison, varnish is usually a mix of shellac and synthetic resins dissolved in spirit/turpentine. Turpentine is fluid/solvent obtained by distilling resin extracted from living pine trees. Incidentally, French polish is not a material, but a process of wood finishing with varnish that mainly utilises shellac to produce chatoyancy (an optical reflectance effect similar to cat’s eye).


Solvents are usually mineral or petroleum in origin, whereas resins also utilised are of plant or mineral origin. Calcium carbonate (mineral or animal) and aluminium silicate are used as additives/fillers to give paints body. A reddish-brown ink or pigment called sepia is prepared from cuttlefish. Quinoline is a yellow dye which necessitates the use of glycerol in its preparation. Also, fish oils are very important to the paint industry. Casein binders are used in water-dispersed paints like distemper. Paints used for road marking may contain shellac. Magnesium stearate, very likely of animal origin, is used as a drier. However, primer is lead oxide of mineral origin.


Lead content in paints


Following a study by the Quality Council of India the Department of Industrial Promotion and Policy declared in April 2011 that it was likely to come out with a regulation restricting lead content in paints to be below the 90 parts per million (PPM) level as per the World Health Organisation standard.


Indian Yellow and other Colours


A special yellow colour called Indian yellow/purree/gogli is made by keeping a cow on a diet of only mango leaves for 2-3 days. This unnatural diet causes it to react in manner similar to an attack of jaundice: deep yellow urine, which is collected in an earthen pot and processed to yield the yellow colouring substance. It was however learnt from a handicrafts village of Orissa that the use of this colour had been discontinued due to cruelty.

Orissa’s Pattachitra painting also have the GI tag. They are paintings on cotton cloth which utilise gum made from a mixture of chalk and tamarind seeds for the base. The colours used are red/hingula (mineral), yellow/haritala (stone), indigo/ramaraja, white (conch shells) and black (burnt coconut shells). The final coat is of lacquer is applied while the painting is held over a fireplace with the back being heated. The brushes are made of hair from domestic animals tied to a bamboo stick.


Warli tribal folklore art paintings (Maharashtra) have been awarded the GI (geographical indication) label. Traditionally henna, indigo, ochre, black (charcoal), earthy mud, brick red and white (rice paste) colours (not permanent) were used for designs on walls or huge murals, but metallic colours on cloth and poster colours on paper are now utilised.


Lime or Choona or Ithil or Sipo Chuna

Calcium hydroxide together with chalk produces a low cost material for whitewashing walls.


For detailed information on Lime or Choona please read

http://www.bwcindia.org/Web/Awareness/LearnAbout/LimeorChoona.html
Brushes

Paints need to be applied and for this either brushes or rollers are used. Rollers are usually made of synthetic materials but that is not the case as far as brushes go because animal hair is widely utilized for many applications ranging from those used to paint walls to artist brushes.


For detailed information on Animal Hair and Brushes please read

http://www.bwcindia.org/Web/Awareness/LearnAbout/AnimalHairandBrushes.html
Page last updated on 07/02/22