Jane Williams and Julie Lauffenburger
Abstract
This study evaluates the effect of erasers on cleaning marble surfaces by methods that have been used to evaluate other stone cleaning treatments. Many conservators already use erasers to clean stone surfaces, ranging from ancient sarcophagi to modern portrait busts but there has not yet been a comprehensive evaluation of the technique and of the individual erasers. In circumstances where localized control of cleaning is desired or where stone is particularly vulnerable to water or solvents, erasers used in electric erasing machines may offer an effective alternative to aqueous cleaning treatments for stone. This study focused particularly on whether the erasers would alter the stone surfaces or leave residues on the surface. A group of erasers were selected that are commonly used by conservators or are readily available in art supply stores for use with electric drafting eraser machines. Information was collected from the manufacturers on the composition of the erasers and was compared to the analyses of the erasers using SEM-EDS. Oddy tests were used to study the reactivity of the materials on unpolished and polished surfaces of Carrara marble tiles. The surfaces were then examined using a reflectometer, UV light, and a microscope at high magnification. Surface tension observations were used to help evaluate the presence of residues left on the marble from erasers.