In my new job, I oversee the preparation and clean-up of all our
cast pieces, though the boss does the actual casting off-premises. I
have not done a whole lot of casting in the past, and all of it was
in silver. At work, we cast silver and several colors and carats of
golds.
I am not very pleased with the way the castings are coming out, and
I’m hoping to get some help understanding what might be done to
improve them.
First-- almost everything we cast is injected. Is it hopeless to get
a good polish on injection waxes, pre-casting? I am not producing
these waxes myself, and I do not want to pressure the wax person
unfairly, but the finish is not what I am used to, on hard carving
wax. There is quite a lot of clean-up after casting.
Second-- Recent castings have had what the boss says is called
"spalling"-- networks of raised ridges that look almost like veins.
What can be done to correct this?
Last, today’s silver flask contained 8 pieces-- 2 rings and 6 flat,
coin-like charms-- and they came out with varying degrees of pitting
on the surface. Some were hardly affected; one was so bad in places
that the pits were too large/deep to be sanded out without wrecking
the piece. This was pretty evenly distributed through the flask, and
did not look like a typical porosity problem. The porosity I am
familiar with is generally close to the main sprue, and is not
confined to the surface. Though, in fairness, I don’t actually know
what causes the familiar porosity, either. Thoughts?
The silver is de-ox, 50-50 new and old; the investment is new; the
other flasks in the casting (various golds) did not have this
problem.
Oh-- and one more question-- Is it really an absolute no-no to get
even the tiniest bit of metal with solder on it in a casting? What
does it do, other than potentially lowering the karat or degree of
purity you can claim?
Thanks a lot,
Noel