Is the operation of casting on platinum a matter of making the
appropriate holding grove and attatching a sprue and encasing in plaster
and running the regular method of burnout and casting OR is there any
helpful hints anyone has to offer?
Thanks again Ron
Hi Ron, I always attatch runners to any delicate spots on the wax. Make
sure you use plaster especially for platinum casting. Use a centrifical
casting machine and throw it as hard as possible. I cast bulky pieces at
1600deg. F. and delicate pieces at 1750. You must use a crucible made for
platinum and absolutely never melt platinum without dark glasses. Don’t
use sunglasses, they will not protect your eyes at all. Good luck Tom
Arnold
Hi Ron, if by “casting on” platinum you are referring to bi-metal
casting, then the answer is actually quite simple. Completely finish the
platinum section to a high polish. Make sure you have some sort of
mechanical interface to the wax, such as a wire, a groove or some such.
Next attach your wax to the Pt. Be sure the wax is slightly larger than
the Pt, so that there is room for finishing. The reason for
pre-polishing the platinum is the fact that it takes a bit more effort
to polish the platinum and it is possible to over-polish the gold in
trying to polish the pt. Now use regular investment for a gold type
burn-out and cast your metal on to the platinum. The metal should give
you a good metallurgical bond and your mechanical interface will help
too. There are some tricks that will solve minor problems, but over all
it is a straight forward process. I hope it helped and you can always
call me for more My #is 949 760-8279. We also have
completed a technical video on platinum bench techniques, that will
truly help the bench jeweler with working in platinum It is called “The
Platinum Expert” and you can obtain a copy by sending $40.00 to PGI, 620
Newport Ctr Dr. Suite 800, Newport Beach CA 92660
Have a platinum dayPLATINUM GUILD INTERNATIONAL USA
Jurgen J. Maerz
Manager of Technical Education, JA certified Master Bench Jeweler
I always attatch runners to any delicate spots on the wax. Make
sure you use plaster especially for platinum casting. Use a centrifical
casting machine and throw it as hard as possible. I cast bulky pieces
at 1600deg. F. and delicate pieces at 1750. You must use a crucible made
for platinum and absolutely never melt platinum without dark glasses.
Don’t use sunglasses, they will not protect your eyes at all.
While using a horizontal casting machine for casting is possible, a much
more successful and safer way is to use the vertical high torque modell
available in the industry. In case of a spill, the metal is confined to
a narrow band, going toward the ceiling, rather than at waist hight wall
to wall. The sheet metal cover is not really a 100% protection. Also,
because of gravity and the way the machine works, a far denser casting
is achieved.
Your fuel should be hydrogen/ oxygen or propane / oxygen. NEVER use
Acethylen or mapp gas for casting platinum. In some cases it is possible
to use natural gas/ oxygen, but only if you can bring up the line pressure
with a regulator.The goggles MUST be at least a #10. I actually recommend
a 11 or 12. There should always be a second person there for safety. If
you need technical help with Platinum casting please call me at #949
760-8279. For all of you who have the number of the Platinum Guild, please
note our area code has changed from 714 to 949
Have a platinum day
PLATINUM GUILD INTERNATIONAL USA
Jurgen J. Maerz
Manager of Technical Education, JA Certified Master Bench Jeweler