Physicochemical approaches to gold and silver work, an overview: Searching for technologies, tracing routes, attempting to preserve

Abstract

Abstract Gold alloys and silver alloys have always been widely employed in the production of significant objects. With high reflectivity, precious metals are perceived as both materials and colours, and can be skilfully combined to produce metallic polychrome effects. Because their structure and composition contain information on their manufacture, use, disclaim and degradation, items in gold and in silver enclose major information on the technologies employed by past societies and on exchange networks. This information can be acquired using appropriate analytical protocols, established according to the nature of the query and the characteristics of the objects. By using physicochemical techniques, it is possible to identify the technologies, materials and tools used by the artisan and, in particular cases, to situate the sources of raw materials and the workshops producing the objects, as well as to follow the trade routes. The aim of this work is to outline major achievements in the study of goldwork and silverwork based on the different physicochemical methods that are available, and to refer the analytical difficulties that have to be faced when studying objects made from precious metals. Based on several examples, three topics are addressed. The first concerns the major role of the techniques of exam when describing shaping, decorating, assembling and finishing; the second considers the search for metallic polychrome effects in some cultural areas; and the third discusses the challenging question of fingerprinting. A fourth section is dedicated to a short reflection on the difficulties related to the identification of the atmospheric corrosion mechanisms of precious metals.