So I was doing my first attempt at wax cast using propane for the burnout,
torch to melt right on the flask and steam to push the silver in. Followed
a book. Using 2, 14guage sprues as entry points to a 3/8" "mold". Since
I'm practicing I was simply using 3/8" wax sprue cut in 1 cm length as my
mold which equates to 1/4 ozt of sterling (give/take) with 1cm 14guage sprue
from top to feed it in a 2" x 2.5" flask. Added 1/4+ozt str to top of sprue
opening and converted to molten with torch. Waited for roll and then
applied pressure (steam) only to have the metal jump up and around the sprue
holes and run down the inside of my flask on to my fire brick. Not a damn
thing was in the mold. It appears the force of the stema drove the molten
silver up the sides and down around the area between where the investment
meets the flask and out.
What happened? Was the flask too hot? Spue holes too small? But if larger
won't the metal solidify in the sprue before the whole it liquid?
Clueless.....panning scraps from my garage floor at the moment
15 years ago