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From: okunewck@psuvax1.cs.psu.edu (Phil OKunewick)
Newsgroups: trial.rec.metalworking
Subject: Re: Foundry Problems
Message-ID: <dqG=un$1@cs.psu.edu>
Date: 7 May 91 21:22:44 GMT
References: <1991May06.152219.16752@ddsw1.MCS.COM>
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arf@ddsw1.MCS.COM (Jack Schmidling) writes:
> I have a basement foundry and am having problems with switching from
> aluminum to brass or silver.
> 
> A pattern that works well in aluminum will have voids when 
> cast in brass or silver.  The current example is a small 
> bell (3 in high).  I get voids when cast in silver or brass 
> but a perfect bell in aluminum.
> 
> I have the same problem with a small saucer but none with a 
> similar condiment bowl that is about twice as thick.

Sounds to me like the metal may be cooling as you pour it.  Are you
heating your mould enough before pouring?  This may solve your
problem.