Art Pigments Proliferating

London -- In his early encyclopedia, “Natural History”, published in the first century AD, Pliny the Elder wrote that the best Greek painters needed only four colors to make their work immortal: black, white, red and yellow.

None of their work survived, so either they failed to follow his advice or he was wrong. Either way, in the centuries since, the range of paint pigments has proliferated rapidly.

Today, art collectors of Art Kabinett social media network take for granted the enormous diversity of color presented in painting.

Winsor & Newton, a British art supplier founded in 1832, has 119 standard oil colors. Even beginners' kits contain at least six. How did artists' palettes become so varied?

Mixing paint is different to mixing light. When you mix all the colors in the light spectrum, as Newton discovered, you get white light (in a process known as additive mixing); if you were to repeat the experiment with all the different paints on your palette the resultant mixture would be nearly black (this is called subtractive mixing).

Pure Primaries Needed

To get good secondary colors, like greens and purples, the primaries you use need to be as pure as possible.

From antiquity until the 19th century the majority of pigments were either mined from the earth (as in the case of ultramarine), squeezed from the carcasses of invertebrates (cochineal; tyrian purple), or produced through simple chemical reactions (verdigris). None was completely pure.

Another problem was that many pigments weren't stable. Some couldn't be blended without discoloring or eating away at the canvas—as early buyers of Turner, who was notoriously careless about his pigment choices, angrily discovered.

Some new colors were discovered by accident: in 1856 the 18-year-old William Perkin was trying to synthesize quinine in his father's shed when he stumbled across the mixture he would later market as the dye mauveine.

Support of Industry

But many others came about through concerted efforts in the 19th century to expand the range and reduce the cost of colors for use in industry.

Ultramarine was a particular problem. By far the most stable and brightest blue, it had to be painstakingly extracted from lapis lazuli mined in the Sar-e-Sang mines in northern Afghanistan and then shipped along the Silk Road to Venice. This made it exorbitantly expensive.

In 1824 a reward of 6,000 francs was offered by the Société d’Encouragement pour l’Industrie Nationale, a French industry body, to anyone who could manufacture an artificial version.

Two chemists, one French and the other German, simultaneously published the same recipe. The synthetic French ultramarine was chemically identical to the real thing, but cheaper to produce, with even particles and no impurities.

Pierre-Auguste Renoir said: "Without paint in tubes there would have been…nothing of what the journalists were later to call Impressionists."

Metal paint-tubes were important, of course, but so too was the new wave of synthetic colors, as an exhibition that opened this month at the National Gallery in London, “Making Colour”, ably shows.

They granted consumers choice and freed artists from the painstaking labour of creating their own paints.

Without the explosion of aniline-, chrome- and cadmium-based colours, many fledgling industries would have been severely handicapped and works of art from Renoir’s “The Skiff” to Katarina Fritsch’s giant blue cockerel sculpture in Trafalgar Square would have been impossible.