Color seems like an easy, marvelous thing when you get that 64 color box of Crayolas as a kid. 64 sticks of pure color. But, of course, color is complicated. It can be impermanent, difficult to obtain, and toxic. To understand the life and chemistry of colors is to peek under the hood. It’s not what catches your eye, but it’s the heart of the drama.

Many paintings are known to be fading; it’s the newer paintings that draw the most concern. To some extent, the older paintings had probably already faded, but the older paintings also used old tried-and-true methods. The works of Jan van Eyck (1390-1441) are considered to be about as colorful today as when they were painted. Van Gogh’s daisies are fading. Renoir’s red has been digitally re-envisioned to show its pre-faded look.

The 1800s were a boom time of chemistry and industrialization, and the art world participated in this expansion too. 12 elements, including sodium and potassium, were discovered between 1800 and 1810. As Chemistry exploded, and new colors exploded. Mauve, the first synthetic dye, was produced in 1856 from coal tar. Renaissance painters (or their apprentices) prepared their own dyes and pigments (think of those scenes from “The Girl with the Pearl Earring” where Scarlett Johansson is grinding various things); 19th century painters bought paint from chemists. Like the disintegrating trade paperbacks of the early 1900s, when industrialization took over an old process, it was faster and cheaper, but took a while to match other characteristics. Books from the early 1800s are often far more intact than the wood-pulp books that followed them.

Artists like Van Gogh knew the strengths and limitations of their new tools. Van Gogh wrote to his brother, noting that the Impressionist paints “fade like flowers,” so he used the brightest colors he could, doing what he could to counteract impermanence. Even now, not all paints are equally durable; here’s a table for watercolors including such measures.

Today, scientists are studying the precise chemistry that causes fading using X-rays. So far, nothing can be done to stop or reverse the fading; they can only be kept away from light. At least we have the tools to imagine their former glory.

Further reading: Victoria Finlay’s Color is a great read on the chemistry of color without diving too deep technically. I reviewed it on this blog a couple of years ago. This article about the history of oil colors is also really fascinating. And finally, if you’re a chemistry buff, the scientific article about Van Gogh’s fading yellow is open source, and available to the public here.