The motivation of this project is to minimise the effects of pollution on Europe's rich heritage of works of art in silver. The chemical reaction of silver artifacts with indoor pollution results in aesthetically disfiguring tarnish which necesssitates regular cleaning in order to maintain the true appearance on which the beauty of these works of art rely. However, a small amount of silver is removed with each cleaning operation. This is most pronounced in inscribed or plated items. The sharpness of the inscriptions is reduced and plated objects may lose their silver coating entirely. Furthemore there are examples (silver threads on historic textiles or Daguerrotype photographs) where the safe removal of silver tarnish is a very difficult issue.
For the protection of silver in display and storage environments different strategies for protection against tarnishing may be appropriate. This proposal seeks to use two metthods to protect silver; absorbents and transparent plastic enclosures. The former method is applicable to display or storage, the latter, for aesthetic reasons is restricted to storage areas. The use of a protective enclosure containing a pollution absorbent would be a compelling combination of pollution mitigation measures, as yet not advotated for silver collections. The results of an international questionnaire confirm that research on these methods of silver protection is now required.
In addition, it is necessary to be able to quantify the concentrations of pollutants in display and storage cases accurately in order to assess the threat to silver collections. Quantification of the relevant pollutants (hydrogen suphide and carbonyl sulphide) at the very low ambient concentrations (down to parts per trillion) which cause silver tarnishing is not standardly available.
The objectives of the project are, therefore, to reduce the disfiguring effects of pollution on silver, thereby avoiding deleterious and time consuming cleaning. These objectives will be achieved by means of collaborative research between Partners who have experience in materials testing (The Netherlands Institute for Cultural Heritage), absorbents for hydrogen sulphide (Glasgow University) and pollutant monitoring (Oxford Brookes University). They will investigate:
1. The development of new, state-of-the-art; absorbents which will remove the relevant reduced-sulphur compounds from display cases and storage cabinets.
2. The assessment of transparent polymeric packing enclosures for isolating individual silver artifacts from the pollutant gases in storage environments.
3. The refinement and development of simple diffusion tube passive samplers to enable the quantification of hydrogen sulphide and carbonyl sulphide gases at the low levels found in silver display and storage environments.
The project will accomplish its objectives by research and development of the appropriate methodologies both in the laboratory and in a range of museum locations with different showcase construction and environmental conditions.
Funding SchemeCSC - Cost-sharing contracts
OX3 0B Oxford - Headington
G12 8QQ Glasgow