I have never worked with Pt before, and was in need of some
advise. I have a design for a forged, anticlastic ring that is
not soldered. Forging around a sinusoid and finishing is the
only work needed. Can some one please tell me the annealing
temp. for pt and any other pertinent info. I might need to know.
Thanks for the help
Chris Slater
Kansas City
http://www.chrisslaterstudios.com
There is a great inexpensive German plat book. I unfortuantly
don’t have it in front of me, but it’s a black soft back book, I
believe it was around $30. It would be a good book for your
project. Annealing temp is 1800 degrees F. Best luck
Joel Retzlaff
It anneals when you heat it to a nice bright orange. Unlike
gold and silver, it takes more than an instant at this temp. Let
it heat soak for a little bit. Thick sections can take as much as
30 seconds. but it’s temp dependent. I heat it bright enough to
be glaringly bright, but still visible clearly to the unshielded
eye, which means still well below any sort of dangerous (in
terms of accidental melting) temps. At that temp, it anneals
very quickly. At a more normal bright red, say 1500-1600 is when
you’ll need to let it heat soak a bit.
However, I’d suggest not annealing much. Platinum work hardens
only slowly, and if this piece will need any of the sort of
spring tension one normally associates with anticlastic raised
work, you’ll want to not anneal, in order to develop as much work
hardening as possible. it’s difficult to work platinum so far as
to get it too hard to move. And it won’t ever really get cracky
or so hard that it won’t move at all, at least not with the
normal iridium/platinum alloys. An illustration… I make my own
wire by melting bits and pieces down into a sort of rough ingot,
just in a groove cut in a soldering block. This longish blob is
then rolled in a square mill. The first rollings require the
mill to be opened up quite a bit to fit the thing through. Then
as it works down, I close down the mill and proceed through the
grooves. The point is that I can, with normal care to avoid fins
etc, roll that thing through the entire range of grooves on my
square mill down to a .9 mm square wire. This will be now about
as hard as iridio platinum will get, but it won’t crack when
bent, and will still be decent wire. Now, to draw this down in a
drawplate it will need annealing, or it will break. But this is
a remarkable degree of reduction without failure of the metal. A
rough undisciplined shaped blob like that, in 14K or 18K gold
would probably not even have survived the initial rough rolling
just to a square shape in the first groove, without cracking
some.
The other suggestion I’d make is to be sure your tools are
properly finished, and to take as much care as you can not to
ding up the surfaces, especially visible inside ones. Platinum
is difficult enough to polish that if you create difficult to
reach areas in the anticlast which then are all dinged up,
you’ll have some trouble getting a good polish/finish in there,
risking things like accidentally creating thin spots in the metal
when you try to work out the dings. That all should be normal
working procedure anyway, but in platinum, it’s even more
important.
Hope this helps.
Peter Rowe