Raymond White and Jo Kirby
Technical Bulletin Volume 22, 2001
Mastic was the preferred varnish at the National Gallery in 1853, according to a report to a parliamentary Select Committee, and continued in favour for at least two decades of the 20th century. It was prepared more easily than a copal/oil varnish, formed a thinner film, dried faster, and was more readily removed by friction or by solvent action.
Dammar varnish was mentioned in this report and discussed immediately afterwards, but not before this date in Britain. Gas chromatography-mass spectrometry and Fourier transform infrared analyses of varnishes applied in the later 19th century confirmed that mastic was commonly used, sometimes with linseed oil and prepolymerized in some cases.
Chromatograms of mastic alone and with additives of drying oil, dammar, gum elemi, sandarac, African copal, and copaiba are presented and discussed with some colour details to illustrate their appearance now. Manila copal-containing varnishes with Venetian turpentine or oil of spike lavender were occasionally found; they had been applied well before 1850.
Additions of oleoresins such as fir balsam and Venice turpentine are discussed, but were not often found by analysis. Some varnishes could be associated consistently with particular restorers known to have worked for the National Gallery in the 19th century.
mastic resin, National Gallery (London, England), paintings, primary source documents, varnish
To cite this article we suggest using
White, R., Kirby, J. 'A Survey of Nineteenth- and Early Twentieth-Century Varnish Compositions Found on a Selection of Paintings in the National Gallery Collection'. National Gallery Technical Bulletin Vol 22, pp 64–84.
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