Book: Bright Earth
Author: Philip Ball
Price: (Penguin, ?9.99)
Colours today are cheap, abundant and short on meaning. It is a far cry from the Florence of 1485, when Ghirlandaio was contracted to paint an Adoration of the Magi with an ultramarine that cost more per ounce than the artist's monthly fee. Good colours were hard to come by, and were valued for themselves as much as for what they might represent. From all over Italy one might send to Venice for the best plant products and minerals; and Venice would have bought from the rest of the known world. Earths were available in Italy-ochre, sienna, and umber. But ultramarine ("beyond the sea") came from lapis lazuli mined in Afghanistan. Blue azurite and green malachite were copper minerals mainly found in Armenia. Indigo came from India.
The most precious textile dyes came from animals. The Romans valued purple above all, culled from a kind of sea snail known as Murex. (Small mountains of shells have been found at Tyre, testifying to an industry which took 10,000 molluscs to make a gram of dye.) In the 1400s, the most highly regarded dye was crimson, made from the kermes insect that lives on Mediterranean oaks.
Early Renaissance painters had only about 25 useful colours, each carrying a particular value, and they were seldom mixed except with white and black for shading. In Sassetta's Life of St Francis, in the National Gallery, St Francis gives one cloak away to a knight, painted in ultramarine; in the next painting he abandons a second cloak (painted in kermes, the richest of dyes) to his earthly father whom he is renouncing for the life of a saint. The symbolism of wealth would have been as evident to contemporaries as it is lost upon us. To look at pictures from that time with no sense of the pigments is like listening to a symphony without knowing the instruments of the orchestra.
Philip Ball, a chemist by training and science writer by profession, makes a fine story of pigment from the ancients to the present day. The oldest cave paintings used natural colourings mixed with vegetable oils. To this the Egyptians added some artificial colours such as blue frit and white lead. Pliny admired the Egyptians for their understanding of how to dye cloth red using resin from the lac insect and the root of the madder plant. Greeks and Romans inherited these techniques, adding discoveries from further east, such as Indian indigo, and cinnabar, a fine red mineral known in China long before.
From the Renaissance on, Ball tells the history of art as much as that of chemistry. Some of the art history is rather black and white but his account is rich in technical details-like the explanation of a non-naturalistic colouring technique in Michelangelo known as cangiantismo, and his way of making surfaces in shadow seem to glow with heat (shifting hues rather than tones for the darker regions, and mixing white to render the lighter regions).
Although a couple of new colours had emerged earlier (like Prussian blue, about 1705), chemical innovation really took off in the first half of the 19th century, with production of inorganic pigments such as chrome yellow (lead chromate, in use by 1809), cobalt blue (1802) and cadmium yellow (1840), all of which yielded families of related pigments. But it was the mid-century mauves and pinks that crowned the age of organic chemistry-and joined in curious ways with the rivalries of geopolitics. In 1856, while trying to synthesise quinine in an east London shed, the teenage student WH Perkin instead accidentally made mauveine. In 1869, Perkin found a commercial way to synthesise alizarin-the main colourant in natural madder root-just as German chemists made the same discovery. BASF and Perkin registered their patents a day apart and carved up the market between them-ruining the cultivation of madder plants in the south of France and profiting magnificently in the aftermath of the Franco-Prussian war. (The French reacted by requiring red army breeches to be dyed only with natural madder; a policy which held until 1915, when they went over to the less conspicuous blue.) The British and German chemists competed to develop new colours, registering thousands of patents a year. When the Germans found a commercial way to synthesise indigo, it destroyed the most lucrative export business in colonial India-and whole regions of the country were ruined.
There has been an explosion of writing on colour recently, with three books on blue, mauve and indigo within three years. For the materials of art, the National Galleries in London and Washington have led wonderful new research. No single book can treat everything-and Ball's topics are chemistry and western art, rather than trade, cultural difference or the popular marketplace. His subject-matter is closest to that of the fine little book Colours by Fran?ois Delamare and Bernard Guineau (Thames & Hudson). No one who liked one will fail to enjoy the other; but Ball gives more detail. There are slips. It is not true to say that Runge's colour sphere "did not find any place for grey": in fact, as with other colour systems that put white at the north pole and black at the south (with the most saturated colours around the equator), Runge put grey at the centre of his sphere. Also, two Giotto transparencies are printed back-to-front.
It would have been useful to include a glossary of the main pigments, their chemical composition, origin and periods of use. It might even have helped to list the old terms of household chemistry, like lye, soda and alum (I found myself reading with the help of a dictionary.)
The fulcrum of his story, Ball stresses, is the ambition chemists have had to predict colour from chemical formulae. The principles of this, however, were never properly understood before the quantum mechanics of the 20th century; and the exact colour of a complex molecule may still, in practice, be no easier to predict than whether it would make a good antibiotic. For all the advances that have given us house paints and car colour, I am more struck by the limits of our technology. A cheap pigment that behaves like lead white without being poisonous has still not been found. Titanium white has covering power and brightness but, in mixture with black, it gives a cool bluish grey, unlike lead white. Vermilion (mercury sulphide) has partly been replaced with cadmium red; but a standard artists' handbook says the new pigment "cannot replace its particular hue." Natural madder has a slight fluorescence that alizarin dyes don't possess. And, interestingly enough, the new colours really do for the most part look new. On some occasions, this is just what we want-like the synthetic blue of Yves Klein, or sweet colourings that no ordinary food would have. But some of the new colours liked by artists have actually proved short-term friends: Van Gogh's chrome yellow has faded, Rothko's lithol red is now an unpresentable mess. Of all the colours in our world, few meet all our hopes-for permanence, quality, non-toxicity and opacity. The ways we have found them are the pigments of a great story.
