Artnet: Leonardo da Vinci Hid Invisible Drawings in His Sketches. Now High-Tech Scanners Have Brought Them to Light

Artnet: Leonardo da Vinci Hid Invisible Drawings in His Sketches. Now High-Tech Scanners Have Brought Them to Light. “Most striking of all are two blank sheets of paper that are now known to hold invisible studies for hands. High-energy X-ray fluorescence has revealed the sketches called Studies of hands for the Adoration of the Magi. The technology also clarifies how these incredible drawings managed to vanish in plain sight over the centuries. Because of the high content of copper in da Vinci’s metal stylus, a chemical reaction transformed the lines into transparent copper salt.”