Pigments

If you had been a Renaissance painter, your art supply
cupboard might have looked something like this.

Today, when an artist sits down at his or her easel (do painters still work standing up anymore?) among the first tasks is to select the tubes of paint needed to complete the painting. Every artist has favorites, those they've fallen in love with and likewise, those they wouldn't touch with a ten-foot brush. In any case they give little though to what their paint is made of, how it is made, or where the different components originate. Most artists probably don't even give much thought to the varying cost of each color the choose, in that it's usually such a minor consideration as to the cost of creating their work of art. That's art now. Art then was a far different matter. Let's go back to the Renaissance era. Earth tones--ochers, sienas, umbers, blacks, whites, iron oxides, etc. were, in truth, "dirt cheap," and for the most part, readily available in most urban art centers. Bright colors were harder to come by--yellows, reds, gold leaf, and especially blues. The color we know today as ultramarine blue, then made from the semi-precious gemstone, lapis lazuli, was literally worth its weight in silver. Formal art commission contracts often specified how much blue (and gold) would be used in determining the cost of the painting.

Earth tone pigments. As the name suggests, they are
basically highly refined "dirt" (and thus, dirt-cheap)

For the benefit of those artists who have never even seen pure pigments before, let me begin at the beginning. A pigment is a material that changes the reflected wavelength of light through selective absorption. Although many materials selectively absorb certain wavelengths of light the materials artists have chosen (or developed) for use as pigments have special properties that make them ideal for coloring other materials. A pigment must have a high tinting strength relative to the materials it colors. It must be stable in solid form at room temperatures. And for the artist, permanence and stability are required properties. Pigments that are not permanent are called fugitive. Fugitive pigments fade over time, or with exposure to light. Some can also eventually blacken. Of course, pigments are used for coloring other items besides paint, including inks, plastics, fabrics, cosmetics, even foods. Most pigments used in paints are dry, usually ground into a fine powder. This powder is added to a binder (or vehicle), a relatively neutral or colorless material, that suspends the pigment and gives the paint its adhesion.

Prehistoric colors--rust red, carbon black, browns,
and sometimes dull yellows (ochers).
 

The very earliest painters had a quite limited palette (above), primarily, if not exclusively, what we call earth tones--various oxides and carbon black (burnt wood or bones). Before the Industrial Revolution, many pigments were known by the location whence they came. These pigments based on locally unique minerals and clays often bore the name of the city or region where they were mined. Raw Sienna and Burnt Sienna came from Siena, Italy. Raw umber and burnt umber came from nearby Umbria. These pigments were among the first to be synthesize, as chemists created modern colors that were more consistent than colors mined from the original ore bodies. The place names, however, remained. Often a contemporary mixture of pigments that replaces a historical pigment is indicated by calling the resulting color a hue, but manufacturers are sometimes negligent in maintaining this distinction.

Australian ochre pits have become a tourist attraction.

As an example, Indian yellow was once produced by collecting the urine of cattle that had been fed only mango leaves. Dutch and Flemish painters of the 17th and 18th centuries loved the stuff for its luminescent qualities, and often used it to represent sunlight. A patron of Vermeer is said to have remarked that that the artist had used "cow piss" to paint his wife. Since mango leaves are nutritionally inadequate for cattle, harvesting this pigment was eventually declared to be inhumane. Today, French ultramarine is manufactured from aluminum silicate with sulfur impurities. Similarly, royal blue, once referring to tints produced from lapis lazuli, has evolved into a much lighter and brighter color, usually formulated from phthalo blue and titanium dioxide (white), or from inexpensive synthetic blue dyes.

Ground pigments become brighter when mixed with various
mediums used in the manufacture of artists' colors.

One of the difficulties beginning artists (and some more experienced as well) have always had in dealing with color is that of equating pigment named paints with their understanding of the infamous color wheel (below). To make matters worse this "wheel," in its truest form, is actually a sphere when all the various tints and shades are accounted for. Thus, when you contemplate the complexities of this ancient color diagram you are, in fact, viewing a gross oversimplification. The "Real Color Wheel" (below) comes about as close as any simplification of the spherical nature of shaded (using complementary colors) and tints (using white) that I've ever encountered. I've attached some of the most common pigment designated paints around the edges. The outermost ring is comprised of tints with shades moving toward the center. The tiny white or black dots indicate some of the more common premixed shades also available under a variety of different names. Keep in mind that color designations will vary (sometimes greatly) among different manufacturers. Likewise, paints labeled "student grade" are formulated with colorless fillers (usually aluminum stearate) up to 2% by weight. That may not sound like much in terms of volume until you realize that aluminum compounds are quite light in weight while some of the more costly pigments are much heavier than others. The stuff is said to offer oil paints a more "buttery" consistency, but they also subtly effect the brightness of the colors.

Note: unlabeled hues are those usually mixed by the artist and seldom manufactured as tube paint.

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For more details regarding the diagram above, click here.