I have read some on anti-tarnish silver alloys. I know there are
several and some might be more affordable than using 5% palladium by
weight in silver, but would that do any good? Has anyone ever tried
that? I have heard from one source that the palladium content needs
to be over 60% for the alloy to be called “tarnish resistant”. Now,
metallurgically speaking, a text I read said that palladium is
miscible in silver at basically all temperatures over the melting
point of silver (960C).
I don’t want to be annoying, just seeing what options are out there
for tarnish resistant silver.
The bottom line is if you are going to work with sterling (92.5% Ag)
alloys you cannot achieve tarnish free alloys there is just too much
silver present and not enough alloy. Argentium is probably the best
of the tarnish resistant sterling alloys available and it will still
tarnish, just slower than standard sterling. Silver sulfide is what
makes up most of the black compound we call tarnish, this is formed
by silver being in contact with sulfur compounds in the air or much
more rapidly by contact with strong sulfur compounds like liver of
sulfur. A good test for whether a alloy will tarnish is immersing it
in liver of sulfur, if it takes on a color from the immersion then
it will tarnish. Using palladium in place of all or most of the
copper in sterling will minimally improve the tarnish resistance but
it will make it a very soft (and expensive) alloy. This is true of
virtually all alloys that don’t contain a significant amount of
copper, as it is the two phase alloy that copper forms with silver
that gives sterling its hardness. Since standard sterling is just
barely hard enough for jewelry use making a softer alloy is not a
good idea. Again Argentium overcomes this by its ability to be
precipitation hardened after fabrication is complete.