Answer:
Historians have commonly believed that paint used before the year 1500 did not contain copper. however, lab techniques have shown that copper is present in the paint of both the mona lisa, painted by leonardo da vinci (1452-1519), a widely-renowned and timeless piece that is one of the most valuable pieces in the louvre today, and in that of another painting known as the sine nomine, also from the same time period, whose painter is unknown—but not found in the paint of any other renaissance painting analyzed. this is strong evidence that the sine nomine was painted by da vinci, as well as evidence that the presence of copper in the paint of a r