July 23, 2020
For all its transcendental appeals, art has always been inextricably grounded in the material realities of its production, an entwinement most evident in the intriguing history of artists’ colours. Focusing in on painting’s primary trio of red, yellow, and blue, Philip Ball explores the science and stories behind the pigments, from the red ochre of Lascaux to Yves Klein’s blue.
Having taken many centuries to figure out what the primary colours are, we are now in the process of abandoning them. The very notion of primaries can now spark furious arguments among colour specialists. Some point out that the trio many of us learnt at school — red, yellow and blue — applies only to mixing pigments; mix light, as in the pixels of television screens, and you need different primaries (roughly, red, blue, green). But if you print with inks, you use another “primary” system: yellow, cyan and magenta. And in the rainbow spectrum of visible light, there’s no hierarchy at all: no reason to promote yellow light above the slightly longer-wavelength orange.
What’s more, even though painters learn how to mix colours — blue and yellow to give a green, say — they quickly learn that the results can be disappointingly muddy compared to a “pure” pigment with the intended colour: it’s especially hard to get a rich purple from red and blue. As a result, artists often think of colour not so much as an abstract property but in terms of the substance that makes it: madder red, ultramarine blue, cadmium yellow. To truly understand what colour means to the artist, we need to think of its materiality. Or to put it another way, what the artist’s palette is capable of producing has always depended on the materials at his or her disposal, and the ingenuity that went into procuring them.
That ingenuity has never been lacking. During the last Ice Age life was nasty, brutish and short, yet humans still found time for art. Tools dated to around one hundred thousand years ago have been found in Blombos Cave on the coast of South Africa: grindstones and hammer-stones for crushing a natural red ochre pigment, and abalone shells for mixing the powder with animal fat and urine to make a paint that would be used to decorate bodies, animal skins, and perhaps cave walls. The paintings made 15-35 millennia ago at Chauvet, Lascaux and Altamira attest to the genuine artistry that early humans achieved using the colours readily to hand: black charcoal, white chalk and ground bone, and the earthy reds and yellows of ochre, a mineral form of iron oxide.1
But the classic red pigments don’t rely on iron minerals, the hue of which is not the glorious red of a sunset or of blood, but of the earth. For many centuries, the primary red of the palette came from compounds of two other metals: lead and mercury. The pigment known as “red lead” was made by first corroding lead with vinegar fumes, turning the surface white, and then heating that material in air. It was used in ancient China and Egypt, Greece and Rome.
For the Roman author Pliny, any bright red was called minium — but by the Middle Ages that Latin term was more or less synonymous with red lead, which was used extensively in manuscript illumination. From the verb miniare (to paint in minium) we get the term “miniature”: nothing to do, then, with the Latin minimus, “smallest”. The association today with a diminutive scale comes simply from the constraints of fitting a miniature on the manuscript page.