Charms, pendants, and rings are just a few items that can be made using a method called lost wax casting. In this process, a wax (or sometimes plastic) mold is used to create a piece of jewelry. This wax mold, called a pattern, is first weighed so the amount of metal required to fill the mold (gold, silver, etc.) can be determined. Then the mold is attached to a base, and a flask is slipped over the base. Once the mold is in the flask, a kind of plaster that looks like pan cake batter called investment, is mixed up, put in a vacuum to get all the air bubbles out of it, and then poured into the flask. It is then left to dry and harden. This takes a minimum of two hours.
Once the investment is dried, the base and flask are removed. Now the piece is put into an oven to burn out the wax. Next a centrifuge is used to force the melted metal into the investment mold. Finally, the piece is cleaned up by filing and polishing it.
Read on for some illustrated instructions.