Decay markers for the preventative conservation and maintenance of paintings

A large variety of pictorial models capable of simulating the ancient polychromes of wall paintings and paintings on mobile supports has been prepared and aged by appropriate procedures under different climatic conditions, such as exposure to UV radiation or chemical pollutants (i.e. NO x, SO x). A comparison of the physicochemical properties of these models, particularly concerning their material components, with those resulting from the ageing procedures revealed significant differences that can be used as possible “decay markers”. Micro-FT-IR, NIR, UV–vis, SEM-EDS, XRD and, where possible, Mössbauer spectroscopy have been used in order to identify surface and/or bulk variations in the physicochemical properties of the samples prepared. Decay markers have been found for aged models containing linseed oil, copper resinate, lead white and zinc white. Moreover, interactions between organic and inorganic components have been revealed. The data obtained have been evaluated also by comparison with the results obtained by other techniques, albeit complementary, (i.e. GC–MS, XPS) on the same pictorial models, within an inter- and multi-disciplinary collaboration