Fig. 2

a François Quesnel, Portrait of a Lady (NG2617), about 1575, oil on oak, 36.9 × 27.6 cm; b paint cross-section from the purple–pink dress, showing the light orange priming consisting of lead white, a little red lead and a little zinc sulphate, on top of which is a light blue layer of smalt and lead white, followed by a pink layer of lead white, red lake and smalt, followed by a final deeper layer of red lake and smalt; c backscattered electron SEM image of the cross-section; d zinc EDX map showing the zinc sulphate in the priming, e potassium EDX map showing the areas where potassium is associated with zinc; f EDX spectrum from a zinc- and potassium-rich area showing that potassium is associated with the zinc; g silicon EDX map showing the location of the smalt particles. Images © National Gallery, London