Scientific analysis and historical aspects as tools in the legal investigation of paintings: A case study in Brazil

The faker makes use of several strategies to give credibility to his work, as for example by copying artist's style or by using artificial aging techniques. The characterization of artistic materials, such as pigments, binding media and supports through chemical and/or physico-chemical analysis, coupled with art historical information is essential to establish the non-authenticity of works of art. This paper presents a contribution in a legal case regarding paintings attributed to important Brazilian and European artists such as Candido Portinari, Juan Gris, Camille Pissarro, and Umberto Boccioni, among others. In the investigation, modern synthetic painting materials were identified in all the ground layers of the suspected paintings. The use of diverse instrumental analytical techniques such as Fourier transform infrared spectroscopy, polarized light microscopy and pyrolysis-gas chromatography/mass spectrometry enabled this characterization. The results demonstrated the presence of titanium dioxide, calcium carbonate and kaolin as inorganic components of the paints, and polyvinyl acetate copolymerized with vinyl versatates or diisobutylphtalate as binding media in the ground layers of the paintings. The results obtained, along with art historical information and art technological studies, were very important in the judicial process, due to the possibility to use titanium dioxide and polyvinyl acetate copolymerized with vinyl versatates as chronological markers.