Microchemical investigation of ancient silver and gold plated luxury objects

By means of the combined use of different analytical techniques, the micro-chemical structure of silver- or gold-plated objects dating back to the Greek, Roman, Barbarian, Dark and Middle Age periods have been studied in order to identify the different used plating techniques, and to elucidate some aspects of the manufacturing techniques. The attention has been focused on coins and luxury objects such as jewels, coins, buckles and decorative items. This innovative approach has been utilised in order to gain further insight into the micro-chemical structure of the external regions of the objects, as well as of the bulk metallurgical features. The results indicate that several methods were used in ancient times by the craftsmen, including the simple mechanical application of a thin malleable gold foil, or the most complex and sophisticated method based on the use of mercury i.e., the so called fire gilding. This latter method was used to coat copper or silver core with a thin film of precious metals and could be considered the most important advance in the technology of gilding to be made in antiquity.