Science and art

There are many good reasons to talk about art at the Royal Institution. When Michael Faraday lectured here, art and science were still on speaking terms, and J. M. W. Turner came to consult with him about pigments. Humphry Davy studied the composition of pigments from Roman wall paintings. James Clerk Maxwell first demonstrated the principles of colour photography at the Royal Institution in 1861; and when the Institution was founded in 1799, it appointed the Yorkshireman William Savage to address the needs of the nascent colour printing technology, in particular by remedying the shortage of coloured inks.

How nice it is that art and science have once again come to represent a respectable combination. The Creating Sparks festival, hosted by the British Association last September in South Kensington, acknowledged this by looking at some of the many ways in which art and science overlap. But I notice a tendency to talk about this conjunction in abstract terms, such as whether or not the two activities draw from the same wellspring of human creativity. We hear about how scientific themes appear in art, and how art might be used to help convey scientific ideas. This is all very good; but I want to talk about connections far more concrete. I will talk about advances in art that could not have happened without science - and conversely, and perhaps more surprisingly, advances in science that stemmed from art. And let me be clear that by science, I mean both pure and applied science, because I think that the distinction often made between science and technology is a false one. The science of my talk is chemical science, which has always been an eminently useful and practical business.

The topic I shall address stems from a very simple question: from where do artists get their colours? Figure 1 shows a painting by Wassily Kandinsky, in which we can see a fantastic range and brilliance of colour. We tend to take these colours for granted now: one finds racks upon racks of bright paint tubes in any art shop. Look closely at the labels, and you will find that many of them contain complex synthetic chemicals. How long have they been available? Did Kandinsky have them? How about Monet, or Turner, or Rembrandt? In short, just how did art get its colours, and how has the invention of new colour affected the paths that art has taken?

It might seem a little strange to study art by looking at its materials. But it would not have seemed strange at all to painters of the Middle Ages or the Renaissance. They were deeply engaged with their materials, out of sheer necessity - for they made their own paints from the raw materials. These painters knew that the quality of their art depended vitally on the quality of these materials. Although that is still true today, few contemporary artists have a comparable relationship with the physical characteristics of their medium. One suspects there is a perception almost of something vulgar about such tangible aspects of art. This means not only that some artists have undertaken ill-informed and disastrous experiments with paints, but that art itself is in danger of losing touch with its roots as a practical craft - a craft that happens to have produced some of the most glorious expressions of the human spirit.

Colour in antiquity

It might have been more appropriate if Creating Sparks had happened this year, for this is the 150th anniversary of the Great Exhibition in Hyde Park, a truly monumental intersection of art and science. The Exhibition was housed in Joseph Paxton's Crystal Palace. The man responsible for decorating it was a designer named Owen Jones, and Jones decided that his colour scheme would emulate that of ancient times. The stereotypical image of the buildings and temples of classical Greece shows sun-bleached, bone-white stone. But Jones knew better. The Victorians had discovered to their astonishment that not only the walls of these buildings but the statues too were once painted in bright colours. Jones planned for the Crystal Palace to be painted in primary red, yellow and blue.

As it happened, his plan was thwarted, because interior-decorating paints at that time did not have the brightness he desired, and the results were a paler, watered-down version of his aspirations. But what about the paints of the classical world? What were they really like?

The most ancient art we know of, such as that painted fifteen millennia ago in the caves of Lascaux (Figure 2), employed pigments dug straight from the earth: ground-up minerals such as red and yellow ochre and chalk. These 'earth' colours are generally quite dull. The ochres are iron-rich minerals, akin to rust. For black, cave artists usually used charcoal. And so the most common colours were those that nature offered most abundantly: black, white, red and yellow.

In 1969, two anthropologists named Brent Berlin and Paul Kay claimed that colour words appear in all languages in the same sequence. Some aboriginal languages distinguish only two colours: black and white. Others have three: black, white and red. When a fourth term is added to the language, it is always either yellow or green, followed by the other of these two. So the quartet of black, white, red and yellow corresponds to a kind of universal four-colour scheme - you never find languages with, say, terms for only red, yellow, blue and orange, or just red and blue. Can it be just coincidence that these four basic colours are the ones that nature offers most readily?

The Egyptians used these pigments too; but they had a broader palette. Egypt in the third millennium BC had a surprisingly sophisticated chemical technology, some of which was learnt from Mesopotamian culture. Moreover, in Egypt the artists were priests, and art was a devotional practice. Artworks were awarded supernatural power through religious ceremonies. So the production of pigments was a socially important task.

One of the most renowned pigments of the ancient world was Egyptian blue, which is made by grinding up a copper-containing compound: calcium copper silicate (Figure 3). This substance is made by melting sand together with copper minerals and chalk. It was probably discovered as an offshoot of the manufacture of blue-glazed stones called faience, which were first made in Mesopotamia around 4500 BC. Faience was used for decorative purposes, and stimulated experiments with materials and kiln designs that probably also lead to the discovery of glass and of copper smelting, which ushered in the Bronze Age.

So this blue pigment probably arose by chance as a side-product from a technology developed for making something else entirely. This is a common pattern for pigment discovery, which recurs right through to the twentieth century. Without the social demand for substances such as glass, soap, metals, dyes and plastics, it is unlikely that many of the technologies for pigment manufacture would have evolved, or would have been economically viable. The artist's palette is partly a by-product of industrial technology.

The Egyptians also knew how to use simple chemistry to make artificial whites, yellows, reds and greens, such as verdigris, made by letting vinegar fumes corrode copper. So their colour scheme was really quite rich.

The Greeks knew of all these pigments, but they did not necessarily use them all. Some of the most renowned painters of classical Greece in 600-400 BC, such as Apelles and Nicomachos, chose deliberately to restrict their palettes to just four colours - and sure enough, these were black, white, red and yellow. It is not clear why this four-colour palette was adopted. One idea is that, as the Greeks moved beyond the flat, two-dimensional pictograms of the Egyptians to depict three-dimensional shading, they found it difficult to achieve a harmonious balance of tones with too many colours. Whatever the case, the austere four-colour palette was eventually deemed the dignified and sober choice for serious artists, a prejudice that persisted in Imperial Rome. Pliny in the first century AD condemned artists who used so-called florid colours - even the reds and yellows, he said, ought to be earth colours rather than brighter pigments such as cinnabar which, ever since Alexander the Great's conquests, could be imported from the East. Pliny feared that the sensuousness of Oriental colours would corrupt the supposed purity of artistic expression developed in classical Greece, which manifested itself in art as an elevation of the importance of form over colour. One can find this xenophobic prejudice even in the art theory of the twentieth century.

But unfortunately for Pliny, public taste was more 'vulgar', delighting in colour. His injunctions did not stop craftsmen from using bright colours for interior decorating, as we can see from the richly coloured wall fragments and murals that survive at Pompeii (Figure 4). Unfortunately, the mural techniques of the ancient world often don't preserve the colours well. Exposed to sun and air, they fade, discolour or flake off, leaving buildings and statues bare of their original colours and making the classical world seem now like a much more drab, pale place than it really was.

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