A COMPARATIVE STUDY OF SILVER CLEANING ABRASIVES

The intent of this investigation was to identify a relatively safe and effective abrasive cleaning system for use on museum silver. This research, per- formed at the Getty Conservation Institute (GCI) and the Los Angeles County Museum of Art (LACMA), was coordinated with the actual cleaning, polishing, and lacquering of a large silver collection at the museum. Tarnished sterling silver samples were cleaned using 13 abrasives and 2 carrier fluids. The amount of silver removed, the relative amount of tarnish remaining, and the appearance of the silver surface after cleaning were assessed. Independent bench tests were per- formed by LACMA conservation staff to compare subjectively the results produced by the various abrasives, carrier fluids, and abrasive support cloths. It was found that calcium carbonate, gamma alumina, and chromium oxide suspended in deionized water containing a nonionic surfactant removed tarnish successfully and caused the least amount of damage to the silver. The mechanisms of polishing and factors to be considered in selection of museum silver cleaning systems are dis- cussed.