David Harvey
Abstract
The use of photographic dulling sprays on reflective surfaces to eliminate glare is widespread: one needs only to tum the pages of the major auction and exhibition catalogues to appreciate the scope of use of this material. In July of 1997, conservators at the Metals & Arms laboratory at Colonial Williamsburg discovered that the Scottish silver Newbattle Kirk Cup made by George Cleghorne (ca. 1644-1646) had been coated with a commercial photographic dulling spray by a volunteer photographer. The photographer had applied the spray, photographed the silver cup, and then wiped the surface with a cloth. The cup was further affected in storage by an HVAC failure during a thunderstorm in which the relative humidity spiked to 90% within a 24-hour period.
The silver cup had many black tarnish spots that, when viewed under low magnification with a binocular microscope, appeared as etched tide rings around seams and pores in the silver. The micron-sized, abrasive crystals from the dulling spray were driven into every seam, pore, and scratch in the silver. A new scratch pattern appeared where the photographer had wiped the surface.
Traditional silver cleaning and polishing techniques would exacerbate the situation; the micron sized crystals had to be released from the silver substrate before tarnish removal could be undertaken. A treatment plan was formulated using a non-ionic Pluronic surfactant in solvent and focused ultrasonic energy from a Misonix XL 2007 ultrasonic wand. After the particles were completely released from the surface a traditional silver cleaning treatment was carried out.
Although the treatment was successful, it was extremely time-consuming. Any time saved in photographing the cup with the dulling spray was far outweighed by the labor-intensive treatment. Furthermore, some irreversible damage to the object did occur. This is a problem that can and should be prevented, and it is hoped that dissemination of this paper will help raise the awareness of our colleagues in museums and auction houses who photograph historic and artistic metal objects.