Victor Gonzalez

Victor Gonzalez is a CNRS researcher in the PPSM laboratory at ENS Paris Saclay. He received a PhD in Chemistry from the Sorbonne University in 2016, conducted at the C2RMF in Paris. He worked in the Netherlands, first as a post-doc in the Material Science Department of TU Delft, and then as a junior scientist at the Science Department of the Rijksmuseum in Amsterdam. In 2021, he became a Marie Curie fellow at the PPSM laboratory before joining the CNRS in 2023. His work is aimed at chemically revealing the production methods and dynamics of ancient pictorial matter, through the development of innovative analytical methodologies based on a combination of X-ray and optical techniques.

ABSTRACT

Deciphering the Synthesis, Use and Alteration of Historical Pigments at the Multi-scale

Victor Gonzalez⁽¹⁾

(1) Université Paris-Saclay, ENS Paris-Saclay, CNRS, PPSM, 91190, Gif-sur-Yvette, France

Omnipresent in paintings since the antiquity, inorganic pigments are key materials of art history. Collecting accurate chemical information on them is essential to achieve a better understanding of ancient pictorial practices, as well as to develop new conservation strategies. However, this objective faces several scientific challenges. First, pigments were obtained in the past following complex chemical syntheses, whose parameters are not always known to us. Secondly, painters were combining these materials in variable formulations, and applied these formulations with their own unique artistic techniques, resulting in a strong heterogeneity of the hybrid [pigment(s) + binder] paint systems. Finally, paintings are dynamic objects: chemical interactions within paint layers can result in the in situ formation of non-original organo-metallic and/or inorganic compounds. The presence of these neo-formed materials can threaten the optical and/or physical integrity of artworks.

This communication will present recent research aimed at deciphering the past synthesis, formulation by artists, and potential alteration mechanisms of historical pigments. A special focus will be put on the advantages of multi-scale chemical analysis to tackle the chemical complexity of the composite paint systems. At the micro-scale, the analytical power of synchrotron radiation, notably using structural analysis via X-ray Powder Diffraction (XRPD), enables to discriminate between the multiple inorganic compounds present in paint layers, and also to provide detailed information on their composition and microstructure. At the macro-scale, the development of chemical imaging prototypes, based on X-ray or photoluminescence, enables the charting of crystalline species on the entire surface of historical paintings. The talk will illustrate the complementarity of structural and molecular data collected at the multi-scale on carefully designed model samples, historical paint fragments and entire artworks. The case of lead and cobalt-based pigments and their associated alteration products will be specifically discussed.