Primary Colors

With a palette of around 17 million colors at his fingertips, today's computer artists have virtually no limits to their basic materials. It's difficult to imagine, then, how painters of previous generations coped with a more limited range of hues. According to the Roman historian Pliny, artists in classical Greece, for instance, used only four colors: black, white, red and yellow. Pliny added that the restricted palette was the proper choice for sober-minded painters. Whether the artists of antiquity agreed is not recorded.

In his new book, Bright Earth: The Invention of Colour (Viking; 434 pages) science writer Philip Ball puts forward the theory that it is the materials that were available to painters — as much as the ideas and aesthetics of the age in which they lived — that directed the development of painting. He traces a history of art from earliest times to the modern era, but seen from a scientific perspective that relates the development of the chemistry of paints to progress in artistic styles and practices.

Humanity's ambition to portray the world was originally limited by the earthen tones and plant dyes that were immediately at hand. Taking those elements and adapting them for use in painting is an innovation that Ball dates back only 4,500 years. The oldest synthetic pigment is known as Egyptian blue frit and was produced by firing in a kiln a mixture of one part lime (calcium oxide) with one part copper oxide and four parts quartz (silica). The resulting hue was widely used in Egyptian wall paintings.

In the Middle Ages artists' palettes suddenly burst with color. This was thanks to the arcane art of the alchemists, sometimes also colorfully called chrysopoeian adepti, whose aim was to turn lead into gold and whose experiments consisted largely of heating minerals until they changed color. Thus, they often inadvertently uncovered the sumptuous hues of medieval painting.

The most highly valued color of the Middle Ages was ultramarine, the intense blue pigment made from lapis lazuli quarried in what is now Afghanistan. Because it was the most expensive color available it was considered the most suitable for portraits of the Virgin Mary, hence the custom of showing her always clad in blue. Not only was ultramarine's source material costly, but the process of turning it into paint was also complex and time-consuming. The ground-up stone was mixed into a paste of melted wax, oils and resins, which was then kneaded in several lye solutions to wash out the blue particles, which settled at the bottom of the liquid.

Although alchemists found the majority of colors in minerals like malachite (green), azurite (blue), orpiment (yellow) and realgar (orange), they extracted others from plants and even insects. One of the Middle Ages' most distinctive pigments, kermes — from which the word carmine derives — was extracted from a wingless insect, kermes vermilio, that lives on scarlet oaks around the Mediterranean.

As the range of colors expanded during the 15th century, so artists sought to break out of formulaic devotional art and into more natural representations. At the same time that perspective and light and shade appeared in painting, a new technique for binding pigments assisted the Renaissance artist's striving for naturalism. The result was oil paint. Flemish artist Jan van Eyck introduced the new medium, and with it new techniques of building up colors in layers. Until then pigments had been bound by quick-drying egg yolk, but now artists began to use drying oils — primarily linseed, nut and poppy — as binders, allowing more variation in intensity and hence greater depth of color.

From the Renaissance until the late 18th century little changed in paint technology. But then the science of chemistry was revolutionized, and with it art. Once scientists discovered that the elements consisted of things other than Aristotle's earth, air, fire and water, newly discovered chemicals opened up a vast new palette. Cadmium yielded a vibrant new yellow and orange, chrome gave a range of yellows and greens, and cobalt new blues. With the appearance of the new colors, artists like J.M.W. Turner began experimenting with new techniques. A Turner seascape made up of primary reds and yellows, mauves and orange had a contemporary critic spluttering it was as if "done by a Rembrandt born in India."

Turner eagerly seized on the new colors and was lucky enough always to use pigments that stayed true. But sometimes colors betrayed artists. Working in 16th century Italy, Giovanni Bellini, Raphael and Tintoretto used a copper resinate green made from verdigris combined with turpentine resin. But the resin sometimes reacted badly on exposure to light, turning the green black. Even modern pigments have been unstable. Mark Rothko used a recently formulated Lithol red for a group of two panels and a triptych that he donated to Harvard University, not realizing the damage that would be caused by exposure to light. The dark pink and crimson he chose in 1962 to represent Christ's suffering on the cross and Resurrection are today light blue.

The arrangement of chapters in Bright Earth is somewhat haphazard. Midway through, just after discussion of the impact that newly discovered pigments had on Impressionism, Ball dives off into a history of dyes, mentioning that many of today's major pharmaceutical companies started as dye manufacturers, then returns to his chronological study of developments in painting, printing and now computer graphics. Despite this mildly irritating flaw, the book is an intriguing synthesis of art and science. What Ball does in Bright Earth is what artists have always sought to do: open our eyes.