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Properties of cast versus wrought platinum


#1

Dear Orchid members. I am considering getting a ring cast in platinum
which is basically a woven wire design. My question is, how good is
the quality of cast platinum these days, when compared to wrought
metal/wire ? Is it a lot more brittle or quite good these days ? The
’wire’ thickness would ideally only be 0.7mm. I appreciate your
advice.

With thanks,
Benjamin Storch


#2

Dear Benjamin

It depends on your caster. I have had things like this cast in
Platinum and they have been fine, get a caster with a good
reputation, who casts Platinum regularly and is used to it. Casting
does save a lot of material.

Regards
Hamish


#3

Benjamin- Tim and I prefer hand wrought. We’re old school though. We
do use cast platinum when the job calls for it, but if it’s gonna be
.7mm wire, I’d fabricate.

Have fun and make lots of jewelry.
Jo Haemer
www.timothywgreen.com


#4

Hi Hamish;

Casting does save a lot of material. 

Yes and no. I’m not implying you’re wrong, just want to add some
for others on the forum. Some shapes requiring piercing
out of sheet will create a lot of “drop” or scrap. Not much you can
do with it until you have another design where they are useful or you
do platinum casting yourself. The casting houses won’t use your metal
as they fear contamination of their metal plus they don’t charge that
much for casting but make their money on marking up the metal, as
much as 30% over cost. Now, there’s a limit, more or less, as to how
thin a casting they can do, so waxes for platinum tend to need to be
a bit on the heavy side, adding cost. You can thin them down, but the
caster will put a lot of heavy sprues on it to get it to fill, and
they won’t bother to saw them off close to the casting, they’ll just
clip them near it, leaving chunks of platinum for you to saw off that
they’ll charge you for. I just got a platinum casting back with $100
worth of those that I will only be able to send in for scrap.

But fabricating the design would have taken a lot more time and
yeilded a whole lot of scrap pieces. Six of one, half dozen of
another. Remember, a fabricated piece will be easier to finish than a
cast one, at least in platinum, but you’ll incur more time forging,
bending, and drawing wire, and maybe you’ll have to turn a lot of
metal into filings to get it where you want it. Finally, working
periodically in the total darkness from those really dark glasses you
have to wear for soldering platinum takes a little patience… place
a solder pallion, it falls off, you take off the glasses and replace
it, put on the glasses, it falls off again… you can’t stick it on
with flux, you can’t use flux, and sometimes a little spittle works,
not always.

So, all in all, it’s a judgement call. But, an experienced designer
craftsman will chose a method, material, and design that all work
together. Exploit the potential of the material, consider the
challenges in the execution, forsee the customer’s experience in
wearing it. You may notice that a lot of old platinum pieces are
assembled from thin elements, pierced, engraved, a lot of bright
cutting. Platinum excells at that kind of thing, you can fabricate
intricate pieces because it’s so hard to melt it before the solder
flows (usually they used palladium solders, hiding the seams in the
construction). And, if you polish your gravers properly, it cuts like
butter and leaves smooth, bright finishes. When a gold smith carves
waxes for platinum, their first efforts tend to surprise them at how
heavy these turn out, or how difficult it is for them to be cast.

David L. Huffman