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Stones in the mold


#1

Hi everybody,

I was wondering if anyone had ever left diamonds in a wax mold,
then poured molten gold into the mold. Is it possible to do this?
Any thoughts would be appreciated.

Chris Davidson


#2

Yes it is possible to cast stones in place people have been
doing it for years. There are some heat sensitive stones that
won’t survive. There is quite a bit of info available in past AJM
magazines, past threads on this list and suppliers of investment,
ect. Usually the people doing it are people mass producing less
expensive jewelry. Its fun to do, synthetic ruby will survive and
is cheap to play around with. Special investments are sold for
this and particular burnout cycles recommended. You really don’t
want to quench the flask after casting, that may doom almost any
stone. I wouldn’t try it with anything expensive. It will work
with a a common 6-8 hour burnout cycle and no quenching after
casting. We prefer to set the stones after casting because you
can polish beneath the stones prior to setting. You get a much
crisper, sharper setting, I think. Call Ransom and Randolph or
Kerr.

Mark P.


#3

Something I should have added about casting stones in place is
that you don’t need to buy special investment. The only thing you
should do is add boric acid to the investment , it will help
prevent damage by oxidation during the burnout cycle and protect
them a bit from the contact with the molten metal during casting.
The boric acid should be mixed in the water prior to adding the
investment powder, helps to mix evenly. Actually you are supposed
to mix in the boric acid into 82 degrees Centigrade water at 15
grams per 450ml of water not to exceed 40 grams per 1000ml of
water. Then cool to room temp and add investment, but hurry
because the boric acid really speeds up the set up time. Its also
recommended that you add 5-10 degrees centigrade to the metal
casting temp, to allow for the cooling effect of the stones.
Finally allow to cool to room temp after casting and break out.
Have fun, you will be the coolest castin cat in town.

Mark P.