St John the Baptist

Leonardo da Vinci, around 1508
Musée du Louvre

Saint John the Baptist is, like most of the works of Leonardo da Vinci, painted in oil on wood panel. The opaque and yellowing is due to the ageing of the thick layer of varnish. This thick varnish results in a highly reflective surface, making in-depth analysis difficult, not only with the naked eye, but also with photography.