Peter is correct. WD-40 is a water displacing agent, not an oil. On
an old, used ingot mold, you would not have noticed that it is not
very effective in coating your ingot mold, as the mold probably has a
good amount of soot already attached to it from years of use. As you
discovered unfortunately, a new mold needs a lot more pre-treatment.
Remove as much of the stuck metal as possible before reusing the new
mold. Chip it our, or grind it out. If you are using a two-piece mold
with a polished surface, you should be able to remove this metal by
I would like to add to his suggestions for preparing your mold
prior to pouring your ingots. I used to use motor oil, but always
hated the smokey smell. Now I use wax. Candle wax will work. So will
injection wax, and I always seem to have plenty of that around. I use
an open mold for wire ingots. If you are pouring a small ingot, just
dip a small piece of paper towel in some liquid wax, ball it up, and
push it into the wire channel. Warm the mold until the wax starts to
melt, melt your metal, and pour. The molten metal will stop when it
hits the waxed paper towel. The ingot always drops out with a shiny
finish, and the smell of burning wax is far more pleasant in the
studio that burning motor oil. I have to thank Namu Cho for this
Namu also gave me some very small and thin ceramic crucibles from
Korea. I absolutely love these for doing small melts, as they heat up
very quickly. They are only 65mm in diameter, 20mm deep, with a wall
thickness of just 2.5mm. They are shaped like a shallow bowl. I prep
them by soaking them in water, then slowly drying them with a torch.
Coat with flux, and they're ready to use. With a proper coating, I
can melt platinum in these. I have never seen these in any tool
supply catalog here in the States, but Otto Frei does have a similar
crucible (Pg. 210, C and D). You will need a small pair of tongs to
pick these up. Regular crucible tongs are way to big. You can make a
pair from ordinary hardware store chain nose pliers by heating the
tips and bending them slightly to match the angle of the crucible.
It is a little hard to describe the angle exactly, but if you try to
pick up one of these crucibles by its edge, you will see what I mean.
Another thing to remember is to always forge the ingot before
rolling it. Give it more than just a few "Love Taps." Forge it. You
will get a far better result when you proceed to the rolling mill.
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