Green pigment in paintings turns brown with time

To anyone living in the 21st century, it might not be obvious that Renaissance paintings were once much colorful than they look now. “If you look at the paintings of, say, Leonardo da Vinci, they are very, very dark,” says Didier Gourier, a chemist at the French National Centre for Scientific Research and an author of the study. “But they didn’t always look this way.”..

Presented with incredibly high-resolution images of the paint chips, they contrasted the color changes in verdigris sampled from the center of Bronzino’s painting against verdigris sampled right next to the frame, a shaded area that would have offered protection from light. Their suspicions were proven right when they found the frame-protected paint was far less deteriorated. When Gourier magnified a cracked paint sample from “Pietà,” he found that each crack had darkened, likely due to the diffusion of oxygen in the cracks. “The darkening is not systematic,” Gourier says. This inconsistency helps researchers pick out now-brown verdigris from originally brown paint, he says.

More at Atlas Obscura, via Neatorama.