Tests of laser cleaning on archeological metal artefacts

Abstract

Previously reported experiences on laser cleaning of metal surfaces of artworks such as statues and decorations altered by atmospheric pollution demonstrated the potential advantages of this technique. Here we present a study on the use of laser cleaning on excavated metal objects that typically show alterations and corrosion processes quite different with respect to exposed metal artefacts. Tests were performed on a selection of archaeological samples, such as coins, plates, clamps and ornaments collected from Italian sites. Metals considered in this study are bronze, copper, silver and lead. Different laser systems and different irradiation conditions were employed and compared. The results, evaluated by metallurgic diagnostics and objective observations, indicated that the laser cleaning process was selective and highly precise, allowing the preservation of fine surface details.