My first piece of advice would be to change the investment you are
using. I imagine that you are probably using Kerr investment, which
is one of the worst ones out there (not the worst). I stopped using
that stuff years ago. I highly recommend Randolph and Randsom (R R)
Ultravest, it is the best stuff out there. It’s a little more
expensive, but I don’t use anything else. I get mine from a
distribution company in Los Angeles called Progress Machine Company.
They are very nice. But, if you’re not ready to go this route, I
would start toying with your mixture ratios, perhaps mixing a thicker
solution (when I mix Ultravest you could virtually stand a spoon up
Also, if a rubber mold is set up and cut properly you wouldn’t need
to use an extra pin. The only times I’ve ever had a problem with
something like that was if the wax was too hot and seeped into the
parting, or the pressure was too high, with the same result.
— david thorp