Supervised by Dr Judith Lee, Conservation Scientist, Tate; Dr Bronwyn Ormbsy, Principal Conservation Scientist, Tate; and Professor David Payne, Professor of Materials Chemistry, Imperial College London.
October 2023 –
An example of an oil painting in Tate’s collection with known salt crystals on the surface is Avinash Chandra’s Hills of Gold 1964 (Tate T00724) © The Estate of Avinash Chandra.
Industrially produced artists’ oil paints differ from traditional oils through the advent of factory production processes, changes in formulations (such as the types of oil used) and an increase in the numbers of additives and pigments used. This has resulted in artists’ using oil paints in myriad ways, often producing large-scale works with no varnish layers which are effectively open to the elements. Recent research has uncovered the presence of unexpected salt formation (such as epsomite), which can cause oil-based painted artworks to become water sensitive, impacting the effectiveness of current cleaning methods. These salts are known to form in paintings where magnesium-based fillers are used, particularly cadmium yellow and French ultramarine oil paints, however we do not fully understand why. Temperature, lighting conditions, pollutants, relative humidity and priming layers are all known to contribute to or be associated with salt formation. This project aims to further understand the conditions under which epsomite and other salts form, to help inform optimal storage and display conditions, and possible mitigating measures to slow crystal formation and development. Case-study paintings with known salt formation and experimental mock-ups will be investigated using a range of imaging as well as chemical, mechanical and surface analysis instrumentation at Tate and Imperial College.