Multilayered Portraits

In many of Leonardo’s portraits, it is almost impossible to say when one colour ends and another starts – and this is evident in some crucial parts of his paintings, such as the mouths of his sitters.

For example, the Laboratoire du Centre de Recherche et de Restauration des Musées de France, in collaboration with the European Synchrotron Radiation Facility, reported that Leonardo used up to 30 layers of varnish to achieve the subtle shading around the mouth of the La Bella Principessa (a portrait attributed to Leonardo by Martin Kemp as recently as 2011).