What is tarnish and why is Argentium Silver tarnish resistant?
What is tarnish?
Why is Argentium Silver tarnish resistant?
Accelerated tarnishing trials
Tarnish test video
Frequently asked questions
Related documents
What is tarnish?
Tarnish is the term given to the discolouration of metal surfaces, caused by exposure to, or contact with sulphur compounds in the atmosphere and sulphur-containing materials/substances, e.g.:
- Air pollution
- Rubber bands
- Latex
- Some foods (including eggs, mayonnaise, salad dressing, onions)
The silver and copper in sterling silver react with oxygen and sulphur to form tarnish compounds.
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Why is Argentium Silver tarnish resistant?
Argentium Silver alloys contain a small quantity of germanium. The germanium oxidises preferentially to the silver and copper in Argentium Silver, to form a transparent germanium oxide surface layer. This protective oxide gives excellent tarnish resistance.
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Accelerated tarnishing trials
The series of photographs below show samples of standard sterling silver (left) and Argentium 930 Silver (right), photographed at 30 minute intervals whilst being exposed to hydrogen sulphide fumes.
Start of test 30 minutes exposure 60 minutes exposure
Independent accelerated tarnishing trials have been carried out by CATRA (Cutlery & Allied Trades Research Association). Their report can be downloaded from the list of files at the end of this section.
Accelerated tarnishing test video
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Frequently asked questions
Q. Will finishing processes permanently remove the protective germanium oxide?
A. The protective germanium oxide is able to replenish itself through the migration of germanium atoms to the surface; tarnish resistance can therefore be sustained, even when the surface is abraded or polished.
Q. How do heating processes help to improve the tarnish resistance of Argentium Silver alloys?
A. Heat encourages the germanium atoms to migrate to the surface where these atoms react with oxygen to form the protective germanium oxide.
Q. Why do Argentium Silver articles benefit from a wipe with a silver cloth?
A. Some silver cloths contain 'thiols'. These compounds form a strong chemical bond with Argentium Silver and help to give the surface extra protection from everyday pollutants, finger-marks and water-marks. Argentium thiol products are in the process of development. Goddard's Longterm Silver Cloths and Tiffany & Co. polishing mitts are recommended.
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Related documents
'Tarnish resistant Argentium Silver' data sheet (pdf download)
CATRA* report 956994: 'Tarnish Testing of Silver Alloys' (pdf download)
* CATRA (Cutlery and Allied Trades Research Association) website: www.catra.org
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