*3.2. Binding Media and Other Identified Compounds*

The FTIR spectra from all the examined paint samples depicted characteristic bands at around 2925, 2850, 1730, 1460, 1160, and 720 cm<sup>−</sup>1, confirming a consistent use of drying oil. Furthermore, the presence of zinc soap was confirmed by an absorption peak at 1539 cm−<sup>1</sup> in *Countryside in France* (sample 7) and *Landscape in Switzerland* (sample 20), while lead soap was found in French lady (sample 16) by an absorption peak at 1514 cm<sup>−</sup>1. The formation of metal soaps can be explained by the probable reaction of free fatty acids from the oil binder with metals present in the lead- and zinc-containing pigments [51,52]. The detection of the acrylic resin in three of the investigated samples may correspond to the varnish applied during the conservation treatments [43,53,54].
