Ball: Bright Earth

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Philip Ball, Bright Earth : Art and the Invention of Color. New York : Farrar, Straus and Giroux, 2002. 382 pages, 66 color plates.

For me Bright Earth went beyond interesting: it was exciting. It was one of those rare books I wanted to read as fast as I could and then felt sad when I had finished. I suspect that's because it answered so many questions, some that I didn't even know I had had for years and years. But beyond that, it answered them in interesting ways that were fun to read.

The subtitle of the book, Art and the Invention of Color, sounds ridiculous at first – hasn't color always existed in the world, for all to see? – but is, in truth, less ridiculous than it sounds. He's talking about color as we humans perceive it and use it.

The vast profusion of pigments available to artists today – not to mention commercial paint suppliers – are a very recent addition to the palette that colormakers could create. Many now-familiar colors were invented in the late 19th century after William Perkin's synthesis of mauve touched off an explosion in aniline dyes and the beginnings of organic chemistry. Most everyday colors that we routinely encounter came later, in the 20th century. Accustomed as we are to clothing and cars and other products available in an unimaginable array of shades and tints, the availability of what seems to be any-color-on-demand is a very recent phenomenon.

Although rose quartz acquires its color from titanium or manganese impurities, no such metals tint the rose itself. The colorants in living organisms are organic compounds: discrete molecules containing perhaps several dozen atoms each, with backbones of interlinked carbon atoms. Until the nineteenth century, nearly all dyes were natural products, which is to say, organic substances derived from animals or plants. In addition to being used for coloring textiles, they tinted inks and, fixed to particles of a colorless inorganic powder, were the coloring agents of so-called lake pigments.

Tyrian purple, the imperial color of Rome, was drawn out of shellfish. Blue indigo was the frothy extract of a weed. Madder red came from a root, cochineal from an insect. Today virtually all dyes are synthetic organic molecules, their carbon skeletons custom-built by industrial chemists. While barely a dozen natural dyestuffs proved stable enough to be useful to the ancient and medieval world, more than four thousand synthetic dyes now bring color to our industrialized. societies. [p. 33]

The ancient Greeks painted in four colors and found it more than ample. Various cultures at various times in history have not distinguished colors that modern eyes do. Through medieval times only a handful of pigments were available. Some new pigments started to appear in Renaissance times, but all that was upset for awhile by the ascendancy of oil paint over egg tempera: pigments behaved differently in linseed oil than they did in egg yolk, and painters had to adjust.

The color of the robe worn by the Virgin Mary in painted representations through history is largely a record of which pigments were rarest and most expensive in any particular era. Different schools of painting often arose with changes in pigment technology, most notably, perhaps, the Impressionists. Also, theories about color perception, and apparently color perception itself, has changed through time and affects the style of paintings from different periods. Medieval iconographers, Van Eyck, da Vinci, Michelangelo, Rembrandt, the pre-Raphaelites, Monet, Seurat, and van Gogh all painted with the colors that were available but most thought they were capturing some truth about color in nature and how humans view light and dark.

This emergence [of showing objects in relief, with shadows and highlights] of light and shade as features of the painter's landscape is one of the distinguishing aspects of Renaissance art. For the first time people and things cast shadows. The consequence is plain to see: it is as if, with Giotto, the artist's imagined world suddenly leaps to life.

Needless to say, there is more to the Renaissance than the introduction of a technique for painting three-dimensionally. Giotto's approach is a symptom of a profound change in philosophical outlook that affected all areas of learning in the West. The reason medieval artists did not represent figures and scenes as they "really" appeared is not because they lacked the ability or perceptiveness to do so but because such a goal was irrelevant to them. Painting was a way of telling a story without words. What mattered was that each of the important characters could be clearly identified in the scene, in positions and at a scale that suited their status, and in colors that encoded symbolic meanings and redounded to the splendor of the Lord. [p. 104]

One thing, it seems, that has never been possible is to represent accurately the colors of nature. Pigments have always been limited in their capability. Dyes cannot capture every color imaginable, nor can printer's inks, largely because their "primaries" (the trio of red, blue, and yellow) are not pure enough – the reason why modern color printing always adds black: because the primary inks alone do not combine to a convincing black.

Actually, "theoretically perfect" inks are an impossibility. Just as with the sensitizing dyes in photographic film, the ideal three-color printing inks would each absorb a third of the visible spectrum in nonoverlapping chunks. But the physics of the light-absorption process doesn't permit this: real inks have smooth-edged absorption bands that encroach into one another's territory. this limits their ability to capture colors accurately when superimposed.

You can judge for yourself from any color prints in old books how effectively (or otherwise) printing inks edged their way toward "theoretical perfection." For those too young to have firsthand recollection, it is hard to escape the notion that the events of the world in the post-World War II years took place in an overcharged Technicolor glow of ruby-red lips and phthalocyanine-blue skies, just as World War I was conducted in monochrome.

The extent to which a print is true to the original is always going to be determined by the quality of the inks. They are the chromatic building blocks from which one must try to re-create every color under the sun, and this can never amount to more than an approximation. Vermilion, for instance, has its own unique hue, its characteristic plucking of the spectrum's many strings. To emulate it using cyan, yellow, and magenta – each of which plucks its own blend of harmonics – is analogous to an attempt to reproduce a trumpet sound by mixing, in different proportions, the notes sounded on a piano, a flute, and a tube. One might aim for the same result with a different trio of instruments and obtain an approximation more or less faithful. Thus one's impression of the rich vermilion of a medieval triptych, as viewed in an illustrated book, is utterly dependent on the printer's choice of inks (among other things). The one thing we can say for sure is that this impression will never be identical to the one you would have from standing before the painting itself. [pp. 292—293]

Likewise, modern color-television monitors have whole ranges of unreachable colors for similar reasons: in their needed trio of blue, red, and green, pure green phosphors haven't been found. And pity the poor programmer who has to try to translate the patchwork of colors available on a computer monitor into a different patchwork of colors available on a color printer and satisfy the customer whose understanding of additive color mixing (light and computer monitors) versus subtractive color mixing (pigments, inks, and dyes) is probably inadequate to understanding the challenges.

Colors and pigments and color names and where those pigments come from and what the properties of the paints are fascinate me. Is "cobalt blue" really made from cobalt and why is it blue? What are the sources of pigments and the names for "alizarin crimson" and "vermilion" and "ultramarine" and "rose madder" and "burnt umber"? What do "lake" pigments have to do with lakes? (Nothing at all, it seems; "lake" is a corruption of "lak", which described the process whereby dyes were fixed to a metallic oxide to create the "lake" pigments.)

And meanings change, sometimes significantly, over time. It would be a grave mistake in reading older writing about color to assume that one understands the meanings of even the most obvious color names. For instance, "pink":

Another organic yellow common in northern European painting in the seventeenth century offers us a further glimpse at the mercurial propensities of color terms. "Pink" was a pigment of diverse provenance—recipes identify it as an extract of weld (mignonette), broom, or unripe buckthorn berries—but often of an indisputably yellow hue. Pinks were in fact defined neither in terms of their ingredients nor of their color—for there were also green pinks, brown pinks, and rose pinks. It appears that the noun refers instead, like "lake," to the method of synthesis. Pinks were comprised of an organic colorant carried on an inorganic powder. The distinction from lakes is subtle, technical, and a testament to the attention given to the chemistry of the production process by seventeenth-century colormakers. Lakes are generated through a chemical reaction, as hydrated alumina is precipitated from a solution in the presence of a dye. Pinks, meanwhile, result from a purely physical process in which the dye is attached (mordanted) to an inert white substrate, typically chalk, alum, or baked and ground eggshell. They are thus a kind of pseudolake, distinct from true lakes in that no alkali is used in the making. <be><be> A recipe for pink is listed by Edward Norgate in the seventeenth century, and yellow pink was popular throughout that century and the next, particularly mixed with blue to make "green pink." Rose pink, prepared from brazilwood, was considered different from the lake pigment derived from the same colorant. Toward the late eighteenth century, yellow pink fell into disuse, and although "brown pink" remained in circulation into the nineteenth century, "pink" gradually became synonymous with the light red "rose pink" until eventually the connotation changed from one of manufacture to one of color. [pp. 139--140]

It's a long, long list of colorful stories, and each and every color, it seems, has a story to tell, enough for a thousand-and-one nights. Those stories are nicely recounted in this book, but the big story is much bigger than just a list of names. Colors and color perception and pigments and commerce and religion and physics and chemistry and art are all wrapped up together in one compelling and comprehensive narrative. I couldn't put it down.

-- Notes by JNS