Art historians’ theory that Leonardo da Vinci used lead oxide powder to thicken the paint layers has been confirmed in a recent study of the Mona Lisa. Upon examining the renowned piece with X-rays, researchers identified the presence of a rare chemical compound called plumbonacrite. Intriguingly, Rembrandt also employed a similar technique. “In this case, we have a unique technique of creating a base layer,” stated Victor Gonzalez, the principal chemist at the French research institution, CNRS.

Leonardo da Vinci. Portrait of Mona Lisa del Giocondo.1503—1519