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Discussion Starter · #1 ·
I purchased 3 moulds made from aluminum to cast my 2.200" balls, bore is 2.250. My first mould is full of zinc and may be that way forever as I let it cool to room temp before trying to open it up. I had talked to Rotometals about having them cast me a few with the other 2 and they mentioned that they had too much trouble with aluminum moulds sticking.... Has anyone out there tried spraying the inside of the mould with an anti-spatter spray used by welders? I also wondered if you could even spray the mould with PAM? I would really like to use the moulds I bought but am NOT interested in experiencing a molten metal explosion.
 

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Aluminum is marginal for casting zinc as its melting point is too close to that of zinc. The casting may be "welded" to the mould. You might try some borate eye wash but that is more of a guess than a proved method.

Looking at one anti-spatter spray MSDS leads me to believe that it would not work with the high heat input found in casting zinc shot. Its ingredients are water (60-70%), dimethyl ether (20-30%) and "light mineral oil" (1-3%.)
 

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I was also looking at the ingredients of the anti spatter spray and do not like the water content... I can see a possible steam explosion happening. Guess I'll try spray olive oil and try the first pour behind a barrier...
 

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Olive oil can have a pretty low smoke point, would you be better off with an oil that burns at a higher temp? Guess with the temps you will be working with to melt zinc, there are no vegetable oils that can take that level of heat.
 

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I used to get a mold release product from Magma Engineering... Aero something. It was a grey / black (graphite) emulsion in an alcohol carrier, a brush on. I used it mainly on the steel sprue plates so the sprues would drop off the plates properly. I was casting lead, of course.
 

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I've used Pam successfully in casting projectiles but I think I was casting lead in steel molds at the time. Have never tried casting zinc in aluminum molds, various people told me it doesnt work very well.
 
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