A Critical Review on the Analysis of Metal Soaps in Oil Paintings |
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Authors: | Prof. Francesca Caterina Izzo Matilde Kratter Dr. Austin Nevin Prof. Elisabetta Zendri |
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Affiliation: | 1. Sciences and Technologies for the Conservation of Cultural Heritage, Department of, Environmental Sciences, Informatics and Statistics, Ca' Foscari University of Venice, Via Torino 155/b, 30173 Venice, Italy;2. Head of Conservation The Courtauld Institute of Art, Vernon Square, Penton Rise, Kings Cross, WC1X 9EW London, United Kingdom |
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Abstract: | Up to 70 % of the oil paintings conserved in collections present metal soaps, which result from the chemical reaction between metal ions present in the painted layers and free fatty acids from the lipidic binders. In recent decades, conservators and conservation scientists have been systematically identifying various and frequent conservation problems that can be linked to the formation of metal soaps. It is also increasingly recognized that metal soap formation may not compromise the integrity of paint so there is a need for careful assessment of the implications of metal soaps for conservation. This review aims to critically assess scientific literature related to commonly adopted analytical techniques for the analysis of metal soaps in oil paintings. A comparison of different analytical methods is provided, highlighting advantages associated with each, as well as limitations identified through the analysis of reference materials and applications to the analysis of samples from historical paintings. |
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Keywords: | conservation science FT-IR ion migration metal soaps paint degradation Raman spectroscopy |
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