I have done a great deal of centrifugal casting of silver over the
years. Recently, I attempted casting some small parts (about 1oz)
for a Pocher model car using low-melt metal (not pewter). I made my
two-part mold from RTV rubber. They came out excellently. The
molds have escape paths for air, etc. However, when I poured the
low-melt metal, the resulting cast piece was covered with tiny
pockmarks or bubbles. Since I made an air escape tube in the mold,
I don’t think my mold is trapping air. In fact, the pockmarks look
more like trapped moisture. But where is the moisture coming from?
The RTV has no water in it when it is cured. I really don’t know
what to think . . . ? Do any of you have experience casting with
low-melt metal? Or do you know anyone I might contact? I need some
help. Thanks in advance for any suggestions.