Plating and Surface Treatments on Ancient Metalwork

Abstract

This paper presents an overview of techniques employed in antiquity—in different regions and at different times—for decorating metals by plating or applying surface treatments. Quite often the intention was to disguise metals and alloys to give the impression of better-quality materials. In other cases, the treatments produced special decorative effects and unusual colors.

This paper deals with plating with gold and silver, various methods of gilding and silvering, depletion of gold and silver, and different kinds of artificial patination on various copper-based alloys. The best-known artificially patinated alloys are certainly shakudo-type alloys—that is, black-patinated copper-based alloys containing small amounts of gold and often silver and other metals. These alloys are inlaid with precious metals of contrasting colors and have been discovered in various archaeological contexts and historical times. Several other patinated alloys of various colors, including red, yellow, brown, orange, and olive, often rather similar to Japanese irogane (the word means “colored metal”), have been identified in recent times. The ancient methods of patination of iron will be briefly discussed. Ancient texts related to surface treatments will be commented upon.