Hi Ron;
Check the melting temperature of the metal you are using. Palladium
white alloys usually melt at around 250 degrees higher than nickel
white. Your mold needs to be appropriately hotter when you pour and
don’t scrimp on the sprue system. The metal needs to get in there
quick, so keep them heavy. I also often use several smaller sprues
going to the farthest parts of the casting so that the metal doesn’t
have to pass through any narrow gates before getting to the extent of
the cavity.
Also, I hope you are using a non-crystobolite investment. Palladium
doesn’t like the sulfer in conventional investment, besides the fact
that conventional investment isn’t designed for those higher
temperatures. Also, melting with an electromelt is not advised. Too
much carbon present. When melting with a torch, keep the flame ever
so oxidizing.
David L. Huffman