Argentium sterling silver
Argentium silver is a brand of modern tarnish-resistant silver alloys, containing either 93.5% or 96% silver. Argentium alloys replace some of the copper in the traditional sterling silver alloy (92.5% silver + 7.5% copper) with the metalloid germanium. Argentium's patents refer to percentages of zinc and boron present in Argentium silver. Both Argentium alloys exceed the standard required for hallmarking as sterling silver and Argentium silver 960 meets the standard for hallmarking as Britannia silver (95.84% silver).
Origins and description
Argentium silver is the result of research by Peter Johns at the Art and Design Research Institute (ADRI), School of Art & Design, Middlesex University. The project began in 1990 with research on the effects of germanium additions to silver alloys. Germanium was discovered to impart the following properties to sterling silver:
- Firescale elimination
- High tarnish resistance
- Precipitation hardening and simple heat-hardening properties
- Increased ductility
- Increased thermal and electrical resistance (making alloys suitable for welding and laser forming)
- Environmental advantages (associated with not having to remove or plate over firescale)
Many of these properties significantly affect the traditional methods of working silver. For instance the absence of firescale eliminates tedious and time-consuming steps required by the silver worker using traditional sterling silver. It also eliminates the need for plating the final product which is often done on manufactured items because of the problems introduced by firescale. Tarnish resistance is of significant importance to both silver workers and the wearer of silver jewellery.
Argentium Silver is patented and trademarked by Argentium Silver Company, UK.
Traditional sterling silver has a solidus melting temperature of 802°C (1475°F) and a liquidus flow point of 899°C (1650°F). Argentium 935 silver has a solidus of 803°C (1477°F) and a liquidus of 903°C (1657°F), while Argentium 960 has a solidus of 905°C (1661°F) and a liquidus of 925°C (1697°F).
- Peter Johns (1997) Firestain Resistant Silver Alloys. Santa Fe Symposium On Jewellery Manufacturing Technology. ISBN 0-931913-25-X
- Johns, Peter and Davis, Sam (2007) The properties and applications of Argentium (TM) Sterling Silver. In: 31st IPMI Conference (International Precious Metals Institute)
- Eid, Cynthia (September 2006). "Road Testing Argentium Sterling". Art Jewelry: 25–33.
- "Firestain—The Nemesis of the Silversmith". The Goldsmiths' Company 'Technical Bulletin', Issue 3: 10–11. April 2006.
- Haag, Terry (February 2006). "Shine On Silver". Jewelry Arts & Lapidary Journal: 20–24.
- Martin, Eva (February 2006). "Step by Step – Argentium Silver Box Clasp". Jewelry Arts & Lapidary Journal: 36–42.
- Edge, A. M.; V. E. Edge; J. J. Edge (2005). "Investigation on the Quality of Enamel on Germanium Silver". The Goldsmiths' Company 'Technical Bulletin', Issue 2: 8–10.
- Eid, Cynthia (July 2005). "Argentium Sterling Silver". SNAG (Society of North American Goldsmiths) Technical Newsletter. 13.