A number of methods exist for tarnish testing sterling silver alloys. The basic tarnish test procedure consists of preparing clean or polished sample surfaces, exposing them to high sulfur levels for a specific time and then comparing the difference in color between the samples. The darker the sample, the less tarnish resistant it is. But from a marketing, sales and consumer standpoint, the more pertinent question is: "How long will it take for the silver alloy to discolor in ambient air?" This question has become more relevant with the advent of "tarnish-resistant" sterling silver alloys. This paper discusses a new tarnish test, which establishes the link between accelerated laboratory results and ambient conditions. This was accomplished by determining the kinetics of tarnish film growth and correlating film growth with the degree of discoloration. Once this correlation was established, the atmospheric conditions in various locations were entered into the model to simulate the amount of time it takes for several sterling silver alloys to tarnish.

Author: Samuel A. Davis