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The detection of copper resinate pigment in works of art: contribution from Raman spectroscopy

Authors


  • This article is part of the special issue of the Journal of Raman Spectroscopy entitled “Raman in Art and Archaeology 2013” edited by Polonca Ropret and Juan Manuel Madariaga.

  • This article was published online on 2 March 2014. Errors were subsequently identified in the author affiliations. This notice is included in the online and print versions to indicate that both have been corrected [17 March 2014].

Abstract

Copper resinate is a green pigment widely used by the 16th century painters, as many surveys on Italian and European paintings proved. The pigment is a transparent green glaze, and its color is due to copper salts of resin acids. The oldest recipes suggest the preparation of copper resinate by mixing verdigris with terpenic resins as Venice turpentine (conifer resins) on hot ashes. The detection of copper resinate in paintings is up to this time an analytical challenge. We examined the Raman features of copper resinate (powder and in a mock paint film with linseed oil) and compared them with verdigris. Six laser sources (488, 514, 532, 633, 785, and 830 nm) were used in different laboratories to highlight the drawbacks and advantages of a specific excitation source. The obtained results were applied in the analyses of a famous Caravaggio's painting. For a detailed interpretation and full exploitation of the Raman spectra, Fourier transform infrared spectroscopy measurements were carried out as well. Copyright © 2014 John Wiley & Sons, Ltd.

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