The "Holy Grail" of the silverware industry has been for a truly tarnish-free silver alloy that maintains the color, feel and working characteristics of conventional sterling silver alloys, notably 92.5 % silver (Ag) with 7.5% copper (Cu). The silver-copper alloys are prone also to "firestain," where oxidation of the copper in the surface layers leads to the formation of copper oxides on and below the surface when heating in air. Decades of research up to the late 1980s have largely failed to produce alloys that were commercially acceptable. In recent years, new sterling silver alloys have become available that could offer real opportunities for workers in the craft and industry. Many claims have been made in relation to these, including “tarnish resistance” and reduced incidence of firestain during manufacture. However, questions remain and a lack of understanding of good practice in terms of their application may limit their long-term value and adoption within the industry. The Goldsmiths' Company has undertaken a practical review of two of the alloys now commercially available in the UK with the aim of gaining a better understanding of their application characteristics in a workshop environment. To do this, the Company employed the assistance of four workshops (ranging in size from a designer-maker to a large workshop) and a mint, specializing in making medals, to undertake a series of tests using the new alloys. It also made a comparison with two conventional silver-copper sterling silver alloys supplied by two different companies. This paper reports the results of the review but it must be emphasized that this has been very much a preliminary study. The intention is not to endorse any particular alloy but simply to report the characteristics of the various alloys as found in the workshop exercises and laboratory tests. It contains some observations and opinions of those involved and these should not be construed as scientific facts.

Author(s): Mark Grimwade, Karin Paynter, Karin