I do contract work for a couple different manufacturers and one
of them has outside platinum casting done. The problem is they
use a ring streatcher to size up their rings and they keep
ruining them, they just break up. My question is can you anneal
platinum? Thanks for your help, Matt the Catt
Matt and Catt,
Yes you can anneal platinum. You have to bring it up to orange
or white hot and hold it for 30 seconds approximately and then
about ten seconds later quench in water. Try this and see if this
helps. Of course no stones!
Russ
I have the opposite question…can you actually temper
platinum? I believe that it’s known as a favorite of setters as
it’s one of the “dead” metals. Anyone care to enlighten me???
Reguards;
Steve
Platinum can certainly be annealed. That is probably not the
problem here, however. Platinum castings, in my experience have
a large grain with boundaries that tend to seperate. This is not
conducive to getting good sizing jobs done by stretching. In my
experience, the best bet is to cut the shank and weld a piece of
platinum in. Good luck! Bruce
platinum? I believe that it’s known as a favorite of setters as
it’s one of the “dead” metals. Anyone care to enlighten me???
Seve, I am sure this will bring out many responses which I look
foward to…I do not consider myself a platinum expert but the
concept of dead setting I always was told meant the setter could
coax the metal ( prong ) dead against the stone . Flush , that is
to say…absolutely no space underneath the prong. This is easier
with high carat gold and platinum. I have merely heard it called
dead setting… anyone else ?
Terry Parresol
Steve,
Sure you can anneal platinum. Bring it up to orange color or
white hot and keep it there for about 30 seconds and quench when
all the color goes back out.
Your welcome.
Russ
concept of dead setting I always was told meant the setter could coax the metal ( prong ) dead against the stone . Flush , that is to say..absolutely no space underneath the prong.
Not quite, though certainly this is easier with platinum than
with other metals. The term dead means a lack of elasticity or
springiness, so that when you bend platinum, it stays where you
bent it, without springing back. Thus prongs bent toward a stone
stay tight, without springing away from the stone when you
release the pressure. If you’ve started with a properly cut
seat for the stone, and tighten the prongs correctly, and finish
them aff correctly, you can indeed get them set very close to the
stone with greater ease than with other metals.
As to annealing platinum, it’s somewhat similar to annealing
gold and silver except that you need higher temps. A bright
orange is ideal. White hot is too much, as the metal will start
to get coarser crystals (and with platinum’s already coarse
crystal structure, you don’t need that…) Also, unlike gold
and silver, annealing is not instantaneous. You need to let it
“soak” at that bright orange temp for a while. How long depends
on the thickness of the metal. for 1 mm thick sheet, a good 20
seconds is probably about right. Thin wire will be much less.
Remember when annealing: The metal should be clean first. This
means remove the oil and/or steel residues from rolling mills, be
sure there is no oil or fingerprints or gold/silver filings or
residues on the metal.
the easiest way to affect the above is simply to quickly dip the
metal in your ultrasonic (or traditional boil out solution) and
then steam it off if you’ve got a steam cleaner.
When holding the metal, use carbide or tungston tipped tweezers.
Steel can be used, but will leave a dark stain that MUST be
sanded off before heating to higher temps such as soldering
temps.
Just as with soldering, use a sharp oxidizing flame, and don’t
put the hot metal on a charcoal block, or other contaminated
surface.
Quenching from a lower, red heat, is just fine. Usually water,
not pickle, to avoid spattering.
hope this helps.
Peter Rowe
Russ: Fascinating! But tell me…is’nt platinum a non-ferris
metal and as such, like gold, impossible to temper by merely
heating? Please don’t think I’m trying to be smart, I’m just
curious.
Best;
Steve
Terry:
You are correct. In what I have heard and experienced in
working with platinum, it has no temper. You can hammer it and
push prongs made of it against a stone and there is very little,
if any “spring” to it. A very pleasent characteristic of the
metal. The origional post made me ask the question of the
possibility to temper it. Any info, Jurgen?
Best;
Steve
I have the opposite question…can you actually temper
platinum?
Steve, Platinum work hardens only slowly when you roll or draw
or forge it, but it does indeed work harden. So you can temper
it that way. For iridium platinum, ruthenium platinum, or cobalt
platinum alloys, that’s about your only option.
But we’ve all seen Steve Kretchmers’ tension set rings, and
similar stuff from Neissing (spelling?) These things are done
with tempered, highly elastic metal. You don’t get that with
ordinary platinum Steve Kretchmer developed his own alloys of
platinum that would allow an age hardening/tempering operation,
so after he makes the ring, he can heat treat the darn things to
a highly springy, elastic and hard state. Like that, once a
stone is sprung into the gap in his tension sets, they don’t
loosen without an outrageous amount of abuse. The alloy he uses
for his tension sets themselves, so I believe, he’s kept to
himself. But he’s also developed a less tricky version, more
easily handled and annealed and tempered (etc) that will also
heat treat to harden, though not by quite as much as his own
proprietary one) This alloy, which he’s named platinum-SK, is
now being carried/sold by Hoover and Strong.
Peter Rowe
Peter:
Thanks for your info. I have seen the ads for Kretchmer’s "S"
platinum and wondered just what it was like to work with. I
understand it polishes easier as well but frankly, since I
started using Guesswein’s plat. polishing system, that is’nt a
problem any more. I’ll have to get some for my next project.
Best;
Steve