Lorenzo di Credi's Portrait of a Woman at the Met is one of those paintings that stops you in your tracks.
Painted around the 1490s on a wooden panel, it would appear to be a wedding portrait, as the woman is holding up a simple gold ring. The similarities to Leonardo's Ginevra de Benci at the National Gallery in Washington are striking, in fact, it is now certain that the Leonardo panel at the National Gallery (in the smaller picture, below) was cut down at some point, removing clasped hands that could have been very similar to those in the above portrait. The slightly detached, almost vacant expression of the 'sitter' in both paintings seems to add to their mysteriousness and beauty. Even the unusual framing element of the halo around the head formed by the trees in the background is the same in both paintings. In Lorenzo di Credi's painting the halo is formed using a beautiful green pigment that was used extensively during the Italian Renaissance, known as copper resinate. It was achieved by mixing and boiling a bluish pigment, verdigris (copper acetate) in Venetian turpentine, a thick yellow resin. This yielded a uniquely transparent shade of green (although it often shows an unfortunate brownish discoloration/oxidation as it ages). Both paintings, as nearly all Italian painting up to about the 1520s were painted on poplar, a soft wood that had to be cut relatively thick, as it could warp relatively easily (northern painting in Germany and the low countries used oak panels that could be much thinner, and less susceptible to warping). In the 1520s canvas became much more popular as a painting support, since it was much lighter and more practical, because large paintings could be realized easily. Nevertheless, it always amazes how well early panel painting survived, a testament to the masterly, very complex preparation of these painting supports. The materials and techniques used were a mystery to painters in subsequent centuries, in fact, there are numerous books written during the 18th and 19th centuries, trying to uncover 'the secrets of the old masters'. Modern science has revealed many of these 'secrets', but ironically it showed that you don't necessarily require modern science to achieve stable and lasting works.