CULTURE: X-Rays Reveal Da Vinci Technique on Mona Lisa

Leonardo da Vinci created the intricate shadows on the Mona Lisa's face by using a meticulous technique called sfumato that results in thin layers of oil and resins, new X-rays of the painting reveal. Da Vinci took the technique to new extremes: His 30 or so layers added a tiny amount of paint, the equivalent of half the width of a human hair, reports Gizmodo. "With this mixture it was possible to create a very impressive aspect of the painting—a realistic, like a 3-D painting," says one of the researchers.