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How to cast bronze and other metals with plastic molds.
Some words on how you could use your plastic molds to castmetals.Your first thought when you see this is that the plastic moldwould melt or catch fire! You are right! The way it is done isas follows…This is going to be a story about a foundry that cast propellersfor boats. That is where I learned how plastic molds are used tocast metal.I once rented space in a foundry that cast props. It was a darkand dusty place. Also very hot some days! When the furnace washeating metal. It was a little noisy then to. Big fans runningto feed air into the furnace.Here is how they would use the plastic molds.First they would cast in plaster. Next the plaster casting wouldbe used to make a new mold using sand. This is done in a Sandbox!! I bet you had already guessed that? The plaster pattern isplaced in the box and sand is packed around it. This is specialsand that cannot be reused. It is mixed in a big machine withwaterglass just before it is to be used. This is packed intoplace and CO2 it blown over it to harden it. Once this is ready the metal is heated in the furnace and thenpoured into the mold. It is allowed to cool 12 hrs or so (thisdepends on the size of the casting – bigger equals longer). Onceit has cooled the sand is broken away and discarded. The castingis cooled for another 12 or so hours and then ground andpolished. Copyright © 2005 Delmar Germyn All rights reserved.
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