No alloy in the jewelry Market has till date undergone so many different corrosion tests, and in such harsh testing conditions. Our benchmark to this concern was that of the fashion accessory industry, in which the tests we used are well known.
ACCELERATED CORROSION TESTS
Six accelerated tarnishing tests were selected and used for the evaluation of the corrosion resistance of the new alloys, with different objectives:
RESISTANCE TO SULPHUR COMPOUNDS
Thioacetamide test according to UNI EN ISO 4538:1998 standard (duration: 24 hours).
Sulphur corrosion tests, in their many variants, are the most common way to assess silver resistance to tarnish. This because sulphur compounds are among the most common and relevant agents of aggression to silver; for long time this test was the only one performed and judgement of resistance was made on the base of its sole results.
RESISTANCE TO SWEAT
Perspiration test according to UNI EN ISO 12870: 2009 standard (made for spectacle frames) (duration: 24 hours).
Artificial Sweat test according to NFS 80-772:2010 standard (duration: 24 hours).
These methodologies assess resistance to contact with skin. The item is put in contact with a solution of artificial sweat, either directly to the liquid or to the solution vapour.
RESISTANCE TO ENVIRONMENTAL CONDITIONS
Damp Heat with leather according to UNI EN ISO 4611:2011 standard (duration: 96 hours)
Neutral Salt Spray test according to UNI EN ISO 9227:2012 standard (duration: 96 hours)
Well known in the fashion industry, these tests assess long-term exposure to chemical compounds
present in leather, and the effect of saline atmosphere in hot, humid environments.
RESISTANCE TO CHLORINE
Active Chlorine test according to an internal procedure (derived from UNI EN ISO 105-E03 for textiles industries) (duration: 24 hours).
Known also as “swimming pool test”, this procedure assesses the impact of corrosive chlorine based solutions, such as can be found in bleach, detergents and pool waters. TAA test and Perspiration test are used for a fast evaluation of the corrosion resistance; this tarnishing screening was made on lab samples mounted in resin and then polished. The samples that gave us good results in these two “screening tests” were then submitted to the other four tests.