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05 September 2003

Forcing Metal into a Mold Using Steam

by Roger Hayward
Excerpted from "Scientific American's The Amateur Scientist",
first published in Procedures in Experimental Physics by John Strong.

Molding and casting metal is a useful tool for anyone who builds their own scientific equipment. One of the problems with making casts, however, is that when metal is poured into a mold, it does not always fill the entire space. This can result in air pockets and other imprefections that can render a casting unusable. There are several techniques for causing molten metal to flow into the mold and fill it completely.

One method is to force the metal into the mold with steam. The metal is melted in the top of the mold as before. When it has melted, a large piece of moist clay is quickly pressed down onto the mold. The steam generated will force the metal into the mold. When this method is used, the mold should be placed on a perforated plate to allow the air to escape at the bottom (see below).