Fig. 2

FTIR-ATR spectra (asterisk) of six pigments (a–f) in linseed oil with 5% (w/w) Siccative de Haarlem after treatment with UVA for 726 h and placement in desiccator filled with water for 1080 h. Arrows indicate the presence of characteristic metal oxalate IR bands. Reference spectra of the oil film before treatment (black triangle) and of the corresponding metal oxalates (black circle) are also shown for each pigment. The B/P ratios are given in Table 1