Non-destructive characterization of paintings

The conservation of cultural heritage is a particular field where the use of non-destructive characterization methods is mandatory considering the uniqueness of the object under study. The analysis of paintings presents a number of challenges because of the high complexity of these systems. Depending on the style they are made of several superimposed layers on a support, normally a wooden panel or canvas. Several paint layers are often applied. Usually a varnish layer is applied after drying to protect and saturate the colours. For the studies in this work we have used a set of reference samples that includes two types of binders, tempera and oil, combined with a number of well-known pigments. These paints have been applied on a standard wood support covered by a layer of gypsum to assure a homogeneously coloured and smooth surface. The profiling technique was applied to resolve the structure of reference samples with a single paint layer prepared using the same pigment and two different binders tempera and oil ( see Figure). Besides distinguishing the type of binder, the method resolves the wood, the gypsum, and even the glue layer between wood and gypsum. Such a detailed information may be helpful in assessing the state of conservation of the paintings including the support structure.

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