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Project

Diagnostics for Artworks.

This SEP grant is used to further develop a multi-analytical approach and explore the applicability of electrochemistry complemented with FTIR spectroscopy to the analysis of the reactivity of historical pigments in particular. Electrochemistry examines the reactions occurring at the interface of the electrode and the solution with high selectivity and sensitivity. Degraded pigments generally change oxidation state (redox reaction), caused by various factors such as the environment or chemical composition. These factors can be reproduced and controlled through electrochemistry, thereby identifying the related redox reactions. FTIR spectroscopy provides complementary information on the molecular changes, helping to identify the degradation mechanisms of the pigments. This project is part of an international collaboration and aims at promoting the interaction between the various aspects of diagnosis, bridging the gap between "micro" point-wise analysis methods and "macro" global techniques. It concerns a concerted effort to optimise and extend these methods across a wide range of cultural heritage objects. Pooling them together in a complementary way will lead to widespread benefits across the community. The specific research aim of the SEP experiments is to detect the specific markers of degraded geranium lakes in order to obtain information about the degradation mechanism of the pigment and the structure of the resulting products. Samples from oil paintings of Van Gogh showing problems of discoloration in the red regions will be studied, together with mock-ups of the pure geranium lakes and mixtures with other pigments and binding media combining accelerated ageing and natural ageing. Experiments will be done by Optical Microscopy and FTIR microscopy (MCT detector with a globar source collecting 256 scans with a spectral resolution of 4 cm-1) coupled to complementary techniques (such as photoluminescence and SEM-EDX). Those experiments will be complemented by electrochemical experiments to investigate the degradation processes of the lake material. Geranium lakes will be characterized by cyclic voltammetry and/or differential pulse voltammetry. To ensure the full understanding of the electrochemical behaviour, the experiments will include the main precursor. The expected outcomes of this project are: I) characterize the reactivity of geranium lakes, providing a deeper fundamental knowledge in the chemical nature of these compounds, II) develop specific protection strategies for painting layers applied in historical objects contributing to a better preservation of the cultural heritage and III) to prepare a new ITN application as partner, including the results of the above experiments to further strengthen multi-analytical approaches, central in the application. A postdoctoral fellow will be appointed, also taking the opportunity to explore which European initiatives can be set up in this research domain.
Date:1 Dec 2020 →  30 Nov 2022
Keywords:IR SPECTROSCOPY, PIGMENTS, ELECTROCHEMISTRY
Disciplines:Electrochemical methods, Spectroscopic methods, Material science for conservation-restoration