Technical Information

Sand Casting Glass

1. Glass is melted in a furnace, then held inside at 2300 degrees Fahrenheit.
2. Mold material is prepared by mixing sand with bentonite(volcanic ash, often used in clay) and a little water.
3. The sand mixture is sifted through a coarse screen into a metal box.
4. A mold is made by making a negative impression in the sand.
5. Molten glass is scooped out of the furnace with a steel ladle and poured into the mold.
6. The glass object is dug out of the sand while still hot but no longer molten.
7. Immediately after being dug out of the sand, the glass object is put in a hot kiln (890 degrees Fahrenheit), also known as an annealer.
8. The glass object is annealed: The kiln (and glass contained therein) is cooled slowly, in a controlled fashion. This process prevents the glass from cracking.

Kiln Casting Glass (lost wax process)

1. A rubber mold is made of the object to be reproduced in glass.
2. A wax object is made by pouring melted wax into the rubber mold.
3. A second mold that will withstand high temperatures is made. This is done by enveloping the wax object in investment material (the most common kiln casting investment mold formula is a mixture of plaster, ground silica and water).
4. After the investment sets, the wax object is “lost” or melted out via contact with steam. The void left in the investment (in the form of the wax object) serves as a mold in which to cast glass.
5. Pieces of glass are loaded in the mold.
6. The mold is then fired in a kiln at 1450 to 1650 degrees Fahrenheit until all of the glass has melted.
7. The glass is annealed (cooled slowly, in a controlled fashion; otherwise it will crack).
8. When the glass reaches room temperature the mold material is broken away from the glass object.