As I said, organic pigments are constituted of what was, at some time, plant or animal matter. And again they divide into the natural and those resulting from sophisticated manufacture. The natural ones were made simply by crushing up insect or vegetable tissue (e.g. Cochineal, Gamboge, Indigo, Madder).As you might expect, these were hardly a safe bet for reliability, and except for restoration purposes they have long since been replaced by more stable compounds. I suppose that the one survivor into widespread modern use is Ivory Black, now made from charred animal bones, originally from ivory scraps.
The story is different with the manufactured or synthetic versions. The basis for these pigments is the residue of plants compressed in strata of rock millions of years ago – the hydrocarbon compounds we know as crude oil. In the 18th century chemists were starting to experiment with “coal tar” in order to make lake pigments, that is, coloured liquids which have to be given body with inert powder so as to be used as paint. The results were usually disastrously impermanent, as some portraits by Joshua Reynolds demonstrate. Throughout the 19th century manufacturers produced many “coal-tar” or aniline dyes for industrial purposes but lacked the means to test their permanence. Often, artists would use these brilliant lakes, only to find they would fade in 5-10 years. As a result, by the 1930’s their reputation stood very low. Twenty years later, three synthetic organic lake pigments were regarded as stable enough for artistic purposes: Alizarin Crimson, and Phthalo Blue and Green. The big change came with the adoption of uniform rigorous lightfastness tests by the American Society of Testing and Manufactures (i.e. the AMTS ratings you might be familiar with), the huge expansion of the plastics and chemicals industries in the 1950’s, and the demand for pigments lightfast enough to stand up to, say, tropical sunshine on a car body. Consequently the last fifty years have seen the development of brilliant and very lightfast organic pigments, many with names I find difficult to pronounce.
The quality of pigment that I, as a colourman, can obtain, has never been higher. And as I aim to produce what Chris Ofili has described as “beautifully honest” paint I intend to take advantage of all the advantages of modern paint chemistry. I am not in the business of making twee “old master” colour which will disappoint. Unfortunately, for many large paint manufacturers, the incentives have never been stronger to counter these advances in raw materials by favouring their own cost-benefit at the expense of the ultimate quality of the product. I aim to benefit artists, and not my accountants. Just thinking about making Burnt Umber on a three roll mill excites me. Perhaps I’ll just stop for the day, go home and start painting!