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Annealing Platinum-Ruthinium


#1

Hi Everyone, I have a perplexing problem and hoped that one of you
brilliant jewelers had a suggestion.

I was sponsered by a metal supplier to make a woven bracelet (that I
have done in 24K already) in platinum. I have woven Pt 900, which
to my understanding is Irridium. I use it extra soft and
occasionally have to torch anneal it to soften it more. No Prob.
The supplier suggested (to qualify for the pureness expected by some
countries) that I use Pt 950 instead. The alloy is Ruthinium I
believe. So when I got the 52ft of 28gauge metal to weave it was
too springy, even at a extra soft anneal. I called and they said I
could kiln anneal it myself. I was told 1650 f minimum, 1800 f max
for 15-20 minutes then slow cool. OK, thats exactly what I did and
now my PT-RU is soft enough but is quite black. I am pretty sick
about it and wonder what to do next.

thanks for any suggestions,
t lee


#2

I can’t help you on getting your color back (someone else on list
will help with that I’m sure) but why don’t you just use pure
platinum. It’s quite nice and soft and you will exceed everyone’s
quality needs. Daniel R. Spirer, GG

Spirer Somes Jewelers
1794 Massachusetts Ave
Cambridge, MA 02140
617-491-6000
@spirersomes
www.spirersomes.com


#3

t lee,

Pt/Ru doesn’t oxidize. Ru is pt group metal. So, unless the metal
was contaminated in the kiln I would seriously question the
composition of the alloy. The only 95% pt alloys that I am aware of
that would oxidize are alloys of copper or cobalt, neither of which
are generally used in fabricating. They have a lower melt range
than pt group alloys which make them better for casting. However,
wire can be made out of such alloys and a test to confirm the
composition should be made. Co alloys are slightly magnetic unless
heat treated so try taking a magnet to the wire and see if there is
any attraction.

As far as what can be done to remove the black if you haven’t
already tried you may want to torch heat a portion of the wire to
see if you can “burn off” the black (this won’t help if it is a
non-pt group alloy). If it is a Co or Cu alloy, pickling will help
remove the oxides. You could also coil the wire very loosely and
put it through a cycle of one of those magnetic tumblers, though it
may come out slightly less polished than it was at first and a
tumbler that will hold 50’ of wire may be hard to come by. You
could also attach thhe wire to a vise and go over it with 4/0
sandpaper. On the first pass over the wire don’t let the paper get
charged with metal, just work on removing the oxide layer. After
this initial sanding go back over the wire with the paper that has
been charged with metal. The first pass will remove metal, the
second pass will burnish it and take it to a higher polish than you
may at first guess. You may even want to make a third pass with a
piece of leather charged with 1500 platinum polishing compound.
This is a lot of work but may be one of your only options.

Call me if you have any questions, Larry Seiger 888.551.0063