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Glass Casting Process

The glass casting process involves the creation and use of plaster-based molds. Using plaster-based molds for glass casting is an art.


A variety of processes can be used to accomplish this feat; however, the two most common methods for making plaster-based molds are open-faced molding and lost wax casting.


In both methods, the mold itself is used only once. A plaster-based mold material is mixed with the appropriate percentage of water to create a slurry. This slurry is then poured around the pattern and allowed to set or harden.


After proper curing, the pattern is removed by pulling it from the mold; by steam removal, or by heat removal. After the pattern is removed, the glass can be placed in the mold.


The method of glass placement varies from artist to artist, based on preference and experience.


Open-Faced Molding

Open-faced molding is more commonly used where one side of the final piece is flat, or for less intricate pieces, and involves pouring plaster around a pattern that can physically be removed once the plaster sets.

  1. Pour plaster around the pattern and allow plaster to set according to package instructions

  2. Remove the pattern if it is made of a material that cannot be placed in an oven

  3. Heat the plaster mold in an oven to cure the material

  4. Place glass frit (small pieces of glass) into the mold and melt into the plaster

  5. Once the glass solidifies, remove the plaster

  6. All detail from the original art is transferred from the mold material to the glass object

  7. Final glass casting is complete


Lost Wax Casting

Lost wax casting is more commonly used for three-dimensional or more intricate pieces where the pattern cannot be easily removed by hand (requires the removal of the pattern by heat or steam) and involves creating a rubber master mold of an original piece of art.

  1. Create a rubber master mold of the art

  2. Remove the art from the rubber mold and fill the rubber mold with wax

  3. Once the wax solidifies, remove the wax pattern from the rubber mold

  4. Place the wax pattern into a flask and pour plaster investment around it

  5. Cure the plaster and heat the flask to remove the wax pattern

  6. Fill or pour glass into the mold

  7. Remove plaster from the solidified glass art

  8. Final glass casting is complete

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