MULTI-ANALYTICAL CHARACTERIZATION OF PHTHALOCYANINE ACRYLIC PAINTS THROUGH SPECTROSCOPIC, NON-LINEAR OPTICAL MICROSCOPY AND INTERFEROMETRIC TECHNIQUES

Conference on Lasers in the Conservation of Artworks, LACONA XII, Lacona XII – 10-14 September 2018 PARIS - France-. .-http://lacona12.orgWe report the results obtained from a mostly laser-based multi-analytical study on copper-phthalocyanine (Cu-Pc) acrylic paints. Many artists, among others Magritte, Picasso, Lichtenstein, Mondrian, Kandinsky and Pollock, have extensively used Cu-Pc pigments over the past century. In ancient paintings, Cu-Pc pigments are sometimes present in the form of overpaints, providing evidence of recent conservation treatments. As a rule, a pictorial retouching that infringes the ethical standards of restoration, e.g. overlapping the ancient paint or being excessively recognizable in terms of colour difference, has to be replaced. The removal of modern overpaints requires a selective cleaning, which greatly benefits from a precise quantification of the material present before the process starts, both for documentation and monitoring purposes. The preservation of the integrity of artworks is a priority during restoring operations and diagnosis, thus, the identification and quantification of the materials to be removed is commonly achieved through the application of non-invasive techniques