Laser-induced degradation of lead pigments with reference to Botticelli’s Trionfo d’Amore

The recent analysis of the palette used in Botticelli’s Trionfo d’Amore by Raman microscopy has led to the erroneous identification of the spectrum of a degradation product, most likely that of massicot (orthorhombic PbO), as that of plattnerite (PbO2) [Anal. Chim. Acta 429 (2001) 279]. The error is shown to arise from the laser-induced degradation of both the painting and a reference sample of pure PbO2. The spectrum of undegraded PbO2 is presented, and the common problem of laser-induced degradation of lead pigments in art conservation studies utilising Raman microscopy is discussed.