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Large Silver Casting


#1

Hi everyone

I am working on a project that will weight about 15 troy ozs in sterling
silver. I’ve never cast anything quite that heavy, so I need some advise.
Should I vacuum cast or centrifugally cast? Also, since the piece has a
lot of mass, can you give me some tips as to how I can avoid shrinkage
porosity in such a chunky piece? Maybe some of you have experimented with
the new tarnish-resistant silver alloys. I’d like to use this, but don’t
know if the size of the piece could cause any complications using these
alloys? And last of all, does this alloy behave well in casting ,
finishing and wear? Uups, I lied, there’s one more question: Is it
equivalent to sterling silver in hardness, and what’s a good source? Sorry
for asking so many questions, but if you have even a little input, I’d
welcome it.

Thanking you in advance for your response, Tom Tietze
The Artisan Workshop


#2

That’s allot of mass of molten metal. I would suggest vacuum casting it,
and when melting that much, use a melting furnace. A centrifuge would
have to me massively counterweighted to balance this while spinning.
Largest I have cast in a centrifuge is 5 oz. I don’t feel comfortable
with more.


#3

First the new silver is basically sterling silver, just has a oxidizing
inhibiter, silicon, with any casting you’ll get shrinkage just try not to
over heat your metal, Stern-Leach, David Fell, and Handy and Harmon all
have this new alloy I’m sure. I’ve cast that weight before on a regular
basis just try to do your pour as fast as possiable (safely), and I ONLY
use vaccume casting now, so would recomend it highly!! just make sure you
have a good strong pump!

Good Luck!
Matt the Catt!


#4

An important thing that has not been mentioned is your flask temp.
Whether or not you use a vac machine, the flask temp will crucial for a
good cast. First, on your large piece, does it choke down to a thin
section? A thin section on a large piece can drive your need for higher
flask temp thereby putting the thicker section at risk. If there are no
drasticly thinner spots you’ve got it made. Something that big I cast at
700F, with vac you should probably go just a little bit higher. J.A.