Sandra, Make a hollow wax (slush wax into mold and pour out extra
liquid wax when the “wall thickness” is correct). Cut out or
"drill" holes, 2-4-?? to 1) let investment into the hollow form
and 2) to tie the inner “core” to the outer wall of investment to
maintain the space (what was wax) between the core and the wall
once burned out. Sprue to wax as needed (vent too if needed).
Once dewaxes, burned out and cast, you can get to the investment
inside the hollow form via the holes. Once cleaned out, the
holes are filled, either with a stone, decoration or the cut out,
casted pieces of original wax can be soldered back in place. You
will need to leave some sort of atmospheric opening in the piece
while soldering on it and possibly be able to close this "vent"
as a last operation (much more difficult with silver as so much
heat has to be applied to the entire piece for soldering, there
will be a vacuum inside of hollow form once cooled. Also a
compleatly sealed hollow form can become a
bomb if heated and the inside air pressure gets too high.)
Hope this helps. It is just one way to do this. I am a bronze
caster (sculpture) and I cast most all of the pieces as hollow
pieces. With jewelry, the wall thickness of the casting is going
to be a problem as it is difficult to get much flow distance when
casting as thin as most jewelry items. Most hollow forms are 2
halves (made by stamping and or forming one way or another)
Good luck!! Hope this helps a bit.
MidLife Crisis Enterprises
Cynthias sculptures are at: http://www.mlce.net
A small bronze foundry, no web site yet!!