Photochemical colour change for traditional watercolour pigments in low oxygen levels

Lerwill, A, Townsend, JH, Thomas, J, Hackney, S, Caspers, C and Liang, H ORCID: 0000-0001-9496-406X, 2015. Photochemical colour change for traditional watercolour pigments in low oxygen levels. Studies in Conservation, 60 (1), pp. 15-32. ISSN 0039-3630


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An investigation for light exposure on pigments in low-oxygen environments (in the range 0–5% oxygen) was conducted using a purpose-built automated microfadometer for a large sample set including multiple samples of traditional watercolour pigments from nineteenth-century and twentieth-century sources, selected for concerns over their stability in anoxia. The pigments were prepared for usage in watercolour painting: ground and mixed in gum Arabic and applied to historically accurate gelatine glue-sized cotton and linen-based papers. Anoxia benefited many colorants and no colorant fared worse in anoxia than in air, with the exception of Prussian blue and Prussian green (which contains Prussian blue). A Prussian blue sampled from the studio materials of J.M.W. Turner (1775 − 1851) was microfaded in different environments (normal air (20.9% oxygen) 0, 1, 2, 3.5, or 5% oxygen in nitrogen) and the subsequent dark behaviour was measured. The behaviour of the sample (in normal air, anoxia, and 5% oxygen in nitrogen) proved to be consistent with the 55 separately sourced Prussian blue samples. When exposed to light in 5% oxygen in nitrogen, Prussian blue demonstrated the same light stability as in air (at approximately 21°C and 1 atmosphere). Storage in 5% oxygen is proposed for ‘anoxic’ display of paper-based artworks that might contain Prussian blue, to protect this material while reducing light-induced damage to other components of a watercolour, including organic colorants and the paper support.

Item Type: Journal article
Publication Title: Studies in Conservation
Creators: Lerwill, A., Townsend, J.H., Thomas, J., Hackney, S., Caspers, C. and Liang, H.
Publisher: Maney Publishing
Place of Publication: Leeds
Date: 2015
Volume: 60
Number: 1
ISSN: 0039-3630
Rights: © The International Institute for Conservation of Historic and Artistic Works 2015.
Divisions: Schools > School of Science and Technology
Depositing User: EPrints Services
Date Added: 09 Oct 2015 11:17
Last Modified: 09 Jun 2017 13:55

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