Catherine Defeyt recently defended her first thesis at the Faculty of Philosophy and Letters and the Faculty of Sciences. As a researcher at the European Archeometry Centre at the University of Liège, she has been studying phthalocyanine blue pigments (CuPc) in the field of artistic heritage using non-destructive scientific techniques, with a number of goals in mind. It is not simply a matter of providing information likely to improve the conservation or restoration of works according to the crystalline form of CuPc contained within, but also to reveal chronological markers that allow more precise dating.

What’s the story behind this painting? What does it represent? Why has the painter used such a bright range of colours? What was their state of mind when they created this masterpiece? These are the questions that buzz around the mind of the viewer observing a pictorial work, questions that arouse their curiosity and stimulate their imagination. But beyond these ponderings concerning the work’s aesthetics, its historical existence or its artistic legitimacy, other questions exist relating to an even more mysterious dimension, invisible to the naked eye, but which are just as informative regarding the work’s identity. These refer to its “guts”, its “genetic code":  Which pigments were used in this painting? How have they withstood the ravages of time? How do they manage to absorb the light to reflect it more intensely? Catherine Defeyt, researcher at the University of Liège’s European Archeometry Centre (EAC), is one of the scientists who is endeavouring to reveal one of the most impenetrable facets of a painting, by going beyond its formal appearance to probe the depths and thus uncover the innermost secrets of its very substance.

Passionate about the conservation and restoration of artworks, this young researcher has devoted her doctoral thesis to the study of copper phthalocyanine blue, a pigment that appeared in the 20th century and which is still widely used today in artists’ paints. Its excellent colouristic properties have earned it a place on the palette of many well-known painters such as Kandinsky, Yves Klein, Roy Lichtenstein, etc. Catherine Defeyt chose to explore the characteristics of copper phthalocyanine within the context of one of courses taught as part of the MA in History of Art and Archeometry at ULg. She first studied copper phthalocyanine green before focusing her doctoral research on copper phthalocyanine blue (CuPc), under the direction of David Strivay and Muriel Verbeeck.

“If a pictorial layer of a painting contains phthalocyanine blue and I use aromatic solvents commonly used in conservation/restoration, what are the risks of modifying the aspects of the work?” This question was formulated with a view to providing new indices, useful for the conservation and restoration of paintings containing this pigment, which is sensitive to the action of certain solvents. It was the starting point for the researcher’s reflection, and the cornerstone of her thesis.