The 19th century U.K. landscape painter J. M. W. Turner is known as “the painter of light,” as the layered colors and texture of his paintings helped him convey sunshine cascading through his scenes. Prior to Turner, oil painters had a difficult time conveying such layered colors, partly because of their paint. Early oil paints—a combination of oils, pigments, and resins—took weeks, if not years, to fully dry, making it impractical to layer additional colors on top. But Turner and others added paint matrix, called “gumtion” or “megilp,” a mixture of lead acetate, linseed oil, turpentine, and dried resin from mastic trees. The butter-colored, jellylike concoction enabled oil paints to dry within days, allowing painters to layer on extra colors. Now, researchers have figured out why the mixture works. The lead in the mix generates a highly reactive form of oxygen that reacts with the oils, speeding their drying time. It also catalyzes the formation of an elastic organic-inorganic gel that holds pigments in place when additional paint layers are added, the researchers report today in Angewandte Chemie. Turner and others at the time took advantage, adding new layers of paint on top to give their paintings a vibrancy not seen before.