The finely ground substance that provides color when mixed with liquid to form paint is called pigment. It does not dissolve, or it would by dye. A pigment can be used in different media, such as oils or watercolor, with some provisions: fresco pigments, for example, need to be alkaline-resistant to cope with lime plaster. Traditional Renaissance pigments came from minerals such as rocks and earth–which were made into artificial compounds, such as lead-tin yellow–or came from organic sources. Indigo, for example, was made from a plant and cochineal from insects. Vegetable-based pigments tend to fade with time, whereas other pigments may darken. The transparent green glaze from copper resinate gradually turns brown over the centuries.
The most prized blue is ultramarine, made from the mineral lapis lazuli. It had to be extracted from a single source of mines in what is now northeast Afghanistan. Ultramarine was so expensive that patrons specified, sometimes in a separate contract, where in a painting they wanted it to be used–usually on the Madonna’s cloak. Cheaper blues, such as smart, were used for the sky. The only intense red was vermillion, which was either made naturally from cinnabar, a mineral, or prepared synthetically. Lead-tin was an early yellow; yellow ocher was also popular.
Warm, natural siennas, umbers, and ochres, which make dull reds and mellow yellows, were the staple pigments of the Renaissance and Baroque palettes. Earth colors were stable in oil paint and cheap. They could either be used raw or roasted like coffee to create a richer color. Some artists, including Rembrandt, primed the panel or canvas with an earth color mixture that glowed through the subsequent layers of paint. Any cool colors used contrasted with the overall warmth of the painting.
Carbon-based blacks included charcoal and the warmer bone black, the precursor of ivory black. Lead white dominated easel painting and, in oils, acted as a drying agent. The faster an oil painting dried, the better it was preserved.
Renaissance painting was a team effort. Apprentices spent about four years learning their trade, starting with mixing colors. They could collect their own earth pigments and buy in the rarer ones. They had to grind the pigments until they were fine enough to be evenly suspended in the medium and make the strongest color possible. Once they had mastered preparing materials, apprentices moved on to drawing and painting.
At the end of the 18th century, a wider range of stable pigments was discovered and by the mid-19th century a huge number of strong new colors had emerged. Packaging methods also improved, making paints portable and far more easy to use. These advances transformed the ways in which artists worked and also opened up painting to the amateur artist.
Before the 19th century, artists had a limited range of pigments at their disposal. Towards 1800, chromium was discovered and chrome yellow, viridian (chrome green), and cadmium yellow, orange, and red became available to buy. Naples yellow replaced lead-tin yellow. In the 19th century, a whole raft of artificial dyes produced mauve and more stable blues and greens, such as emerald green (later found to be toxic) and cobalt blue. These pigments were strong in color, cheap, and synthetic, and they worked in every medium from oils to watercolor. Even ultramarine was now made synthetically, and called French ultramarine.
The invention of new painting and three dimensional media in the 20th century was matched by a vast range of pigments, textural possibilities, and finishes. Computer-generated art has widened the artists’s possibilities still further and technological advances gather pace in the 21st century.
Content for this article was taken from Art: Over 2,500 Works from Cave to Contemporary by DK Publishing. Copyright 2008.