Platinum casting isn’t all that hard to do, it’s just different and
a little more hazardous. If you want to do it to save money, it will
take a while to pay off if you’re only doing a few a week, and it’s
probably not worth it. There are a lot more costs than just a torch
and a casting machine too. Crucibles are about $35 each for instance,
investment and divestor aren’t cheap either. The learning curve can
also be incredibly expensive especially if you mess it up a couple of
times. But if you want to do it because it’s fun and you want the
exclusivity of being able to say you cast platinum in-house (and if
Diamond Jim has deep enough pockets and an understanding enough
attitude), it’s really cool. The WOW factor of lighting up the room
with that white hot sloshing ball of platinum is second to nothing
else in jewelry that I know of.
I use a modified cutting torch on LP. I’ve used hydrogen, it is the
best fuel to use with platinum but it’s probably not really necessary
for the number of castings you are talking about. Its two drawbacks
are that the flame is invisible and it is a little expensive to set
up. Hydrogen burns fast and is kind of pricey. Because the flame is
invisible you have to set your torch by feel and sound, so there is a
learning curve to it and it is extraordinarily hot so there is the
possibility of a substantial increase in the hazard level. But if you
can swing it, hydrogen is the way to go. If you are going to cast
more than 50 dwts at a time, hydrogen is the only way to go. LP just
doesn’t have the BTU’s.
I don’t use the coffee can or even a vertical casting machine, I use
a plain old (and I do mean old) Neycraft centrifugal machine with a
couple of modifications. I just can’t justify the expense of a
higher-tech machine when the Neycraft works just fine for the several
castings I do weekly. .
The only real trick to casting platinum is to get it really, really
hot. It’s not like gold where you throw it the moment it is
completely fluid, you have to really let it heat up. There should be
a noticeable white ring around the melt. If you’re not careful you
can melt the torch tip if it’s too close to the melt, no closer than
about one and a half or two inches. A melted tip dripping into the
platinum will definitely screw up a few thousand dollars worth of
metal before you can say “Bob’s your uncle”, not to mention a torch
tip, a crucible and your casting, so avoid doing that. The force of
the flame required to reach casting temperature is enough to blow the
melt around and that can be a bit disconcerting too. Assuming you
used clean metal, if you find cracks in the shank especially near
the gate, you probably didn’t get it hot enough, completely the
opposite of gold. It looks like it’s ready to go well before it
really is, so hold off until you see the ring. You can’t get it too
hot (with LP anyway). Took me a long time to figure that one out.
Casting platinum can be a little scary the first couple of times,
but if you cast gold and silver regularly, you shouldn’t have any
problems. It works pretty much the same, it’s just a whole lot
hotter. Make sure you have good welding goggles and welder’s gloves.
I do it solo, but a second set of hands to load the flask is a good
idea if you can find a brave soul to help. Just watch where that
flame is pointed when it’s not on the metal! It can set stuff on fire
three or four feet away in a nano-second. Make no mistake, casting
platinum requires your full, undivided attention.
Hope this helps, if I can help any more or if you would like a
description of the mods I made to my tools or a picture or two of my
setup or the actual process, let me know offline.
By the way, I met Diamond Jim and Linda of Pineforest Jewelry in
Colorado Springs at the IJO show. Keep your BS filters handy, huh?
Linda’s a strong woman is all I have to say! Say Howdy to both of
them for me.