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Problem with melting platinum


#1

I’m relatively new to working with platinum and I’ve run into a
problem that I hope someone can help me with. I had some scrap
platinum that I tried to melt into an ingot. The way I was shown to
do this was, on the back of an old crucible, melt the pieces and as
they melt move the metal around with the force of the flame so the
pieces form together into a solid piece that can then be hammered
into a shape that can be sized on a rolling mill. This method was
demonstrated to me and I did it myself a while ago. I went to melt
the scraps today but mistakenly used the concave side of a crucible
that had flux in it. Before I went too far I was able to get the
platinum out of the crucible but some of the pieces got flux on them.
I didn’t think that would have much of an impact so I then started
melting the platinum the way I was shown, on the back of a crucible.
The melting was going fairly well and most of the platinum was melted
together but I was interrupted before I finished and I had to stop.
When I came back to finish melting and forming the melted shape, the
platinum was fairly well imbedded into the back of the crucible with
some amount of flux around the metal. I tried to continue melting but
I just couldn’t get the platinum I had just melted to melt again. The
flux melted but the platinum wouldn’t budge and I now can’t get the
platinum off the back of the crucible. I realize that I shouldn’t use
flux with platinum and the flux that is there was from my using the
wrong crucible. I was surprised that I couldn’t get the platinum to
melt again. The torch I was using is very hot and used many times for
melting platinum. Did I contaminate or alter the metal to raise its
melting point? Any ideas how to get the metal off the crucible,
preferably with out breaking the crucible?

Thanks for indulging a novice,
Larry.


#2

I would say to forget the old crucible, smash it up to retrieve your
platinum and get a Wesco melting dish, and blast the heck out of it
(don’t forget to use blue glasses) to get great platinum use the
inside of the dish and make it dance with the torch flame let it do
the waltz inside, it must get as bright as the sun, then with long
tongs grab the whole melting dish when red hot and dunk it in cold
water and flip it and do the same then you will be OK. Don’t mind the
steam it will go.

You will know your platinum is good if you see a galvanized
appearance on the top of the button after it has cooled. It even looks
like small earth quake cracks on the top sometimes that is OK.

Allan Creates
superringfit.com
P.F.F. Hinged Ring Shanks


#3

Platinum does form brittle compounds with silica and boron. It is
very likely you have contaminated the platinum with the flux (boron)
and crucible (silica) you mqy need to refine the platinum and start
over. You need to use a high heat Wesgo crucible as a working surface
for platinum melting or soldering not standard silica fire clay. You
can try the remedy that Allan suggests but if you have contaminated
the platinum it will not help and you will need to refine it.

James Binnion
@James_Binnion
James Binnion Metal Arts


360-756-6550