Due to the recent enquiries regarding ‘Deoxed (sic) silver’ I
thought an explanation of the reasons for the development and some of
the attributes of this material may be useful. Regards, Tony Eccles
Apecs Bright Sterling Silver
Patent no’s. Australian, 688773. Us app 08/637/,802
UK, German, French, Swiss 0752014, Italian 20620BE/2002
The object in formulating and developing this alloy was to overcome
the problems encountered by silversmiths throughout the centuries
associated with the removal of firescale at the finishing stage of
their work. This usually requires vigorous mechanical removal. Also
the objective was to provide a firescale free sterling silver with
the working attributes as close as possible to standard sterling
silver.
This has been achieved with Apecs Bright sterling silver.
Apecs Bright sterling silver is designed to alleviate the problems
associated with firescale or firestain usually found when final
polishing standard sterling silver. An added benefit of this alloy is
its improved tarnish resistance. As with all silver and its alloys it
will tarnish but the tarnish usually takes longer to develop and is
not as intense as standard sterling silver. Firescale and tarnish are
inhibited by the use of either one or both of two elements Silicon
and Germanium. One American alloy developed in 1990 uses silicon
only, as the operative element but is quite soft; it is good for
master pattern making. An alloy developed in England uses germanium
only, as the operative element but needs quite a lot of this
expensive element to achieve the desired result. Apecs Bright Sterling
Silver uses both Germanium and Silicon to achieve a firescale free
alloy in both casting and plate material. The use of Silicon enables
a reduction in the amount of Germanium necessary to achieve the
required working properties, also a reduction in cost over the
Germanium only alloy. Because Germanium is used and is an expensive
element the cost of these alloys is marginally dearer than standard
sterling silver. This small increase in cost is more than offset by
the ease with which it can be polished as well as the higher lustre
achievable due to the well known whitening effect of Germanium.
Although the casting alloy(G7) works in all other aspects as it
should, continuous casting of the alloy proved difficult so a new
alloy was developed (G31) which overcomes this problem. This alloy is
a 950/1000 silver. Although we call Apecs Bright silver firescale
free, firescale can be induced if careless methods are employed. For
instance, the use of fierce or strongly oxidising flame for
soldering.
As with changes in any alloy there will also be small changes to
working practices to be made. For instance the usual oxidising
noticed when annealing standard sterling is not apparent when
annealing Apecs Bright sterling. Consequently if due care is not
taken it is easy to over-anneal or even melt the metal until one is
used to handling it. It is best, at first, to anneal in a low light
to get used to the look of the temperature colour. It should only be
quenched below red heat as cracking is possible. As cast it is
slightly softer than standard sterling silver. With 50% work it is
about the same hardness. With 75% work it is harder.
Vickers Hardness Ingot Cast 50% 75%
Standard sterling
925/1000 85.6 141.6 156.6
Apecs Bright
G7 925/1000 80.5 158.6 172
Apecs Bright
G31 950/1000 80.8 147 160
Apecs Bright sterling silver at present is only obtainable from
Apecs Investment Castings P/L in Melbourne Australia and United
Precious Metals Refining (UPMR), Buffalo NY USA. The UPMR alloy is
designated #57 sterling silver. Partnerships are in negotiation in
Italy. Interest from other areas is invited.