[Continue] Non-tarnish Sterling Silver

Jewelry Discussion
1 
A supplier here in New Zealand (Golden West) advertises a
non-tarnish stg silver. They say this about it:

-resists tarnish
-brighter finish
-easier to work
-hardness 58 HV
-melts 830C-895C (1526F-1643F)

    As they don't disclose what's in it, does anyone here have
any clues as to what's in the remaining 7.5%? Maybe tin is the
alloying component, but I don't think the sil/tin phase diagram
goes up to these temps at any point.

Brian:

I don’t remember seeing anything further on this, but 7% tin
would have a solidus of 850C, but a liquidus of about 920C. A 7%
zinc alloy would have a solidus of about 840C and a liquidus of
about 880C. Either of these are close.

If you hear (have heard) any follow-up could you please pass it
on?

Lee

2

Hi Lee, it sounds like you should be talking to Tony Eccles.
He’s quite a pioneer in alloying and has developed some beaut’
precious metal alloys south of the Equator. Try contacting him on
apecs@ozemail.com.au
kind regards, Rex from Oz

3

We have been using a non tarnish silver for a number of years.
The alloy has .05% pure aluminium in it. Remove .05% of the
total weight be removing copper and replace with .05% pure
aluminium. Add the aluminium to the mix just before pouring or
casting. Must be done in a reducing atmosphere, (lidded
crucible). O.K. for induction melting or Electro-melt furnace,
provided the crucible has a lid. Cannot be done with direct
flame (oxy/acetylene) melting. Always remember that with any
melt, use at least 50% new metal. We still have some pieces we
cast about five years ago. They have not tarnished. They have
dulled, but a rub with a finger will bring back the shine.

All the best. Chris

4 
   We have been using a non tarnish silver for a number of
years. The alloy has .05% pure aluminium in it

Amazing. When I was in high school about 29 years ago, a couple
of guys that were too cheap (poor?) to do a silver casting did
it in aluminum instead. I don’t remember what thier casting
looked like but I do remember being the next to use that
crucible. The contamination had me a little concerned. I ended
up getting the best casting that I ever got in high school. I’ve
never tried to duplicate it. I especially remember having an
oxidation free silver casting.

Bruce D. Holmgrain
Maryland’s first JA Certified Senior Bench Jeweler
@Bruce_Holmgrain
http://www.goldwerx.nu
703-593-4652