When Da Vinci and Botticelli painted their masterpieces, did they wonder if their works would last for hundreds of years? Did they ever think that even if they did, they might look different? Successful painters use the best paints that were available at the time, but they were formulated for their color, not their longevity. And in many of those paintings, what used to be a brilliant green is now a muddy brown.
“Noli me tangere,” which hangs today in a gallery of the Louvre, is one of many Renaissance paintings that features a copper-based pigment called verdigris. When fresh, its shade of bluish green is rare and luminous. But like many pigments popular in the 15th through 17th centuries, verdigris is toxic and unstable, Arthur DiFuria, an art historian at the Savannah College of Art and Design, explained in an interview with Copper.org, the website of a trade group that represents the copper industry. By the 19th century, verdigris had fallen out of fashion—mostly due to its poisonous nature—but no one ever figured out why the brilliant green pigment darkened so severely. Now, researchers in France have sleuthed the chemistry behind verdigris’s shadowy tendencies in a study in Inorganic Chemistry published in September, 2019.
To do that, they had to take tiny samples of the paint from famous paintings, which had to be a pain to arrange. Read what they did, and what they found out at Atlas Obscura.