Typically, silver for use in jewelry is refined to 99.9% purity. This is pure enough for creating standard sterling silver, which only has 7.5% copper added to it to attain the working qualities silversmiths and jewelers have become accustomed to over several hundred years. Although the working qualities of traditional sterling silver are wonderful, the major drawback is firescale/stain that is commonly formed when soldering or casting. To overcome this problem, anti-firescale sterling silver alloys have been developed over the last 10 years. These alloys are more complex, making it essential to know the quality of all alloying components as well as the major metal being alloyed. In working to improve the casting quality of our firescale-free silver alloys, some trace elements still present in the refined silver were discovered to be causing problems. This study discusses the presence of very small quantities of some trace elements - in particular tellurium, selenium, bismuth and antimony - which, although present in only a few parts-per-million, can represent a threat to the production of quality, stable, silver casting.

Author: Anthony Eccles, Gary Lunt