A novel silver alloy with special properties
Invented at Middlesex
Argentium sterling silver is a modern sterling silver alloy which modifies the traditional alloy (92.5% silver + 7.5% copper) by replacing some of the copper with germanium.
Solving a very old problem
How do you change and improve a product that has been successful for eight hundred years? Research by Peter Johns from the School of Arts and Education at Middlesex University set out to do this.
For countless centuries silver has been used for personal adornment, decorative and tableware items. According to experts at the British Museum, about 5,000 years ago it was realised that silver alone was too soft for practical usage and man first deliberately added copper to make a more durable alloy. In the late twelfth century the English Royal Mint was having problems with it’s silver coinage. Henry II invited smelters from Eastern Europe with a reputation for the quality of their silver alloys, to improve his coins at the mint. They established a standard using 92.5 percent silver and 7.5 percent copper. The alloy became known as “easterling silver”, probably because the smelters had come from the east. Eventually the name was shortened to “sterling”, the name that is used today.
The problems of tarnish and firestain
Sterling silver is a beautiful, durable and easily worked alloy, however it also has a very well known drawback, it needs regular cleaning because of tarnishing. The most common reason for silver tarnishing is a reaction with sulphurous gases in the atmosphere. A problem that has got much worse since the Industrial Revolution. Sterling silver also has another defect that often has to be disguised to make the final product fit for sale. It is called firestain, a reddish-purple oxidation that appears on the surface of sterling silver when it is heated in the presence of oxygen. Silver has a unique ability to allow oxygen to penetrate below the surface of the alloy when it is heated to make silverware and jewellery. As the oxygen penetrates, the copper oxidises deep into the alloy where it cannot be dissolved with a normal acid pickle. Removing deep firestain is a time consuming task that can add considerable cost to the finishing of a product. A quick solution is often used that is hidden from the public because they may be shocked to know that their “solid silver” has been silver plated to cover an unsightly surface blemish. The plating is often described as a ‘flash’ because it is so thin and is soon worn away and the firstain is again revealed.
Why have these problems in sterling silver not been solved before? The main reason is hardness. As soon as even a small amount of copper is removed and is replaced by another element, the alloy becomes too soft for commercial use. Just before WW II, aluminium was investigated to prevent firestain and to give tarnish resistance. Although the research achieved these goals the alloy proved nearly impossible to use. This was because of the tenacious nature of aluminium oxide prevented solder flowing when joining components together.
Peter Johns’s research
In 1990, Peter started to research the benefits of alloying the element germanium with silver. Germanium was found to give it unique properties.
Argentium silver is the result of research by Peter Johns at 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:
- 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 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 International Limited.
The pace of change in the jewellery industry has increased at an extraordinary rate in the last few years. Competitive pressure requires production of better quality jewellery with more innovative designs. The Argentium Silver research project has contributed to an increase in the amount of research being carried out by silver producers throughout the world. Argentium has also shown the industry how to apply technology and processes to silver which have not been possible before. This provides new opportunities in application and design.
The first silver/germanium alloy patent, ‘Novel Silver-based Ternary Alloy’, was filed in 1991. This was in advance of any of the other alloys which have since been developed in competition. Johns has developed intellectual property in this and related areas. To date, a total of 16 patents are granted and pending in Europe, USA and Internationally.
United States Patent 6,168,071 (granted) protects the intellectual property covering:
- Grain refining of Sterling Silver alloys containing germanium, to improve physical properties.
- Diffusion bonding and welding processes with Argentium Silver (these processes are difficult to achieve with traditional Sterling Silver).
Diffusion bonding is a method of joining metals together without the addition of a solder or ‘filler’ welding material. Craftspersons using traditional jewellery equipment can easily perform this process with Argentium Silver. The ability to diffusion bond and weld Argentium Silver opens new avenues for the design and production of silverware and jewellery.
The Argentium company
By 2004 the University had established a spin out company under the management of its own commercial division. Professional marketing support was also recruited from within the University. A strategy was developed to establish Argentium as the first ‘endorsement’ brand in the field of jewellery alloys. A new name was also registered world wide, ‘Argentium Silver’. In 2004 Argentium Silver won the first AJM award for innovation at the New York Expo. It is given for products “that are making a difference now and will in the future”.
From 2004 – 2008 Argentium Silver consolidated its marketing position and established a reputation as the premier sterling silver alloy in the US market. Production reached over three million troy ounces annually. In 2008 Argentium Silver was sold by Middlesex University to private investors. The new company is named Argentium International Ltd. The company statement reads
Argentium International are dedicated to establishing Argentium as the global leader and industry standard for premier silver – ideal for those who value quality and wish to rise above the crowded commodity driven jewellery and silverware market.
Argentium® Silver Citations
Citations are an important indicator of the spread of information about Argentium® Silver. They indicate who is reading about the work, who is examining the alloys developed and how international that discussion and exposure is. The majority of citations have been in authoritative publications and at key conferences by keynote speakers.
2009 Book by Mark Grimwade. Title: “Introduction to Precious Metals”. Published by Brynmorgen Press, Brunswick, Maine 04011, USA. ISBN:978-1-929565-30-6.
2007 Technical article by Nancy Howland. Title: “Mystery Silver”, written for ‘Art Jewelry’ Magazine. Publication: November 2007, Pg. 58-60.
2007 Article by David Federman. Title: “Taking on Tarnish”, written for ‘Modern Jeweler’ Magazine. Publication: July 2007.
2007 Presentation by Samuel A. Davis. Title: “A New Paradigm for Tarnish Testing of Sterling Silver Alloys", given at ‘The Santa Fe Symposium on Jewellery Manufacturing Technology 2007', Albuquerque, New Mexico, USA, held 22nd-26th May 2007. Proceedings published by Met-Chem Research Inc.
2006 Technical article in The Goldsmiths’ Company’s ‘Technical Bulletin’. Title: “Firestain – The Nemesis of the Silversmith”. Publication: Issue 3, April 2006, Pg. 10-11.
2005 Presentation by Dr. Sarah Silve (Research Fellow Brunel University) at ‘The Santa Fe Symposium on Jewellery Manufacturing Technology 2005', Albuquerque, New Mexico, USA, held 22-26 May 2005. Title: “Laser Bending of Silver". Proceedings published by Met-Chem Research Inc.
2001 Review in ‘Materials World’, The Journal of the Institute of Metals. Title: “One-stop Continuous Casting Coverage” (Book review of “A Practical Approach to Continuous Casting of Copper-Based Alloys and Precious Metals”). Publication: February 2001, Volume 9, No. 2, Pg. 33.
2000 Book by Dr. Robert Wilson. Title: “A Practical Approach to Continuous Casting of Copper-Based Alloys and Precious Metals”. Published by 10M Communications Ltd, ISBN 1-86125-0991.
2000 Article in ‘Crafts – Decorative and Applied Arts Magazine’. Title: “Conference Report” (Re. ‘A Sense of Wonder’ Jewellery Conference). Published by The Crafts Council. Publication: November/December 2000, Issue 167, Pg. 67.
Research outputs on Argentium in the University Repository
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