Research by Tate's conservation scientists has detailed the effects of keeping works of art in stable, as opposed to varying, temperatures and relative humidities; more recently we have been considering the effects of oxygen on works or art on paper.
'Anoxia' means 'lack of oxygen'. Works of art are, of course, always stored and displayed in air, which includes 21% oxygen. Oxygen in air has largely been accepted as a necessary evil, but current research is questioning this idea. Exposure to oxygen leads to deterioration of most materials through two processes: oxidation and hydrolysis. Light exposure and the presence of moisture play an important role in any degradation: display in gallery lighting and normal air eventually leads to deterioration of each component of the artwork. This is why paper-based works of art are displayed for only limited periods: at Tate, a maximum of two years' display in controlled conditions is allowed in every four year period.
Tate has been investigating the possibility of anoxic display, as well as storage, since the late 1990s. Paper conservators have built frame packages with light-sensitive materials inside to demonstrate how fading of colours can be slowed in low-oxygen conditions. The first step was to build and test a reliable enclosure that could maintain a low-oxygen and/or inert gas atmosphere for up to ten years. Additionally, the enclosure had to be of sufficiently low cost that it could be used for entire exhibitions, and it had to slot onto existing Tate frames. This was achieved during a one-year project carried out in 2004-5 by a former Tate framing technician.
Tate Conservation Science has now obtained funding to carry out in-depth research into the effects of anoxia on paper, pigments and dyes. The project began in September 2006 when two doctoral researchers joined the section for a three-year period. One is a chemist and paper maker. His project includes a review of all previous studies into the effects of anoxia on materials relevant to Tate's collection, especially modern and historic paper. He will carry out experiments to fill in knowledge gaps in the chemistry and degradation of cellulose and lignin, both found in paper, and improvements to the framing package. The latter include monitoring of oxygen concentration without having to open up the frame to do so, selection of the best oxygen concentration for different types of materials, and investigating whether previous and/or proposed conservation treatments affect conditions inside the anoxic package. Detailed analysis of the atmosphere inside a sealed frame is also planned.
The second researcher is a physicist specialising in optics. His project will be to build and use an instrument to measure the light-fastness (fading rate) of pigments and dyes to assess the behaviour of simulations of works of art in anoxia, and later to assess the lightfastness of real works of art on paper at Tate.
At present, due to the lack of detailed knowledge, all works of art on paper are regarded as equally sensitive to light. This research project will lead to a far better understanding of how much light exposure, with and without anoxia, is safe for different types of material. This in turn should make possible safer display of the Tate Collection - and perhaps also allow longer or more frequent display of iconic but delicate artworks. As a result of the research it may be possible to use anoxic display cases to show works on paper such as studies and sketches together with oil paintings at the same light levels (oil paintings normally can be shown at higher light levels than works on paper, so the two types of materials are lit at different levles). The project will also involve an investigation of the commercial potential of innovative framing systems. Results of this Tate research will be made available world-wide.
Initial work was supported by Tate Conservation (Science and Paper sections), and visiting researchers Kikuko Iwai (Japan) and Kate Toyne (United Kingdom) made a significant contribution. The Leverhulme Trust supported framing research by Brian McKenzie. The Public Sector Research Exploitation Fund is currently supporting anoxic researchers Jacob Thomas (paper chemistry) and Andrew Lerwill (optics), in addition to providing support and equipment costs for the research. Stephen Hackney, Conservation Manager, Science, is the principal investigator, dealing with external relations and budgeting, and Joyce Townsend, Senior Conservation Scientist, is research manager. All are based at Tate Britain, in a new laboratory created specially for the project.
February 2007
