Casting without vacuum

Jewelry Discussion
1

I have been nursing the following thought for many years.

If vacuum and centrifugal casting equipment is not available would
the following work on large models: Before investing the model,
copper wires would be attached to the top side of the wax (side
opposite the sprue) that would extend above the top of the flask.
Invest as usual. When the investment sets the copper wires are
pulled out of the investment. The resultant holes would act as air
vents. The investment mold would now be similar to tufa stone
molds. I tried this technique several years ago on a small wax model.
I poured the metal without the use of vacuum or centrifugal
equipment. The casting was perfect except for a very short thin
wire protruding from the model. Just a thought. Lee Epperson

2

Lee. Yes. that would work. It would be fine to just use wax wire in
place of the copper. In other industries these are called risers.
In the commercial sculpture and ferrous lost wax foundries every
thing is done without vacuum or centrigugal assist. Works fine, as
long as your mold temperatures are right. The assists help on thin
sections and detail. So, on thick sections and large models you can
do just fine with solid cristobalite investment molds and gravity
pours. Actually, when I think about it, on a fairly large mold
there is a hydrostatic head on the bottom of a casting that could be
used to assure fill on thin sections. Tom