I'm curious, because I've not tried to alloy for myself in
casting (only fabrication).... Do you alloy the metal at the time
it's cast (i.e., put the gold and alloy metals into the crucible
separately, melt and stir, then inject)? Or do you alloy in a
separate step and pour up ingots or grain that you then use in the
casting? What's the rationale for doing this one way or the other?
Tried it both ways. This is best way I found for me,20 years
If I need 10 grams of gold to cast with, I take 5 grams old metal, 5
grams, subtract from 10 - 5, I multiply 5 X .585 to get the pure
gold, 2.93 grams and add alloy till I have 5 grams. I put old gold,
pure gold, and alloy in the crucible, heat till well melted, I take
the torch off the metal and flux, put the torch back on the metal. I
do not stir, I use the torch flame to roll the metal around, back the
flame off till the top is like a mirror, and let it go. I have
virtually no porosity.
I cast centrifically, I don't know how it works for vacuum casting.
When I sprue for gold, I use a piece of round rod wax the thickness
of a pencil, about 3/4 inch long above the sprue base. Then put the
waxes on the top. I weigh 14 kt at 13.6 x the wax, and add 20%. When
I do it this way any impurities are in the end of the sprue, not
where the sprue meets the piece, and not in the piece.
I have heard quite a few times people state not to overheat the
In my experience it is hard to over heat metal, and you actually
need to really heat up the metal, and the front of the inside of the
crucible so the metal is very fluid