How to use ceramic molds for fused glass

Updated February 21, 2017

At some point, everyone with a kiln makes fused glass. It is a simple project that recycles old soft drink bottles, wine bottles, beer bottles, broken glass objects or food jars. Fused glass projects include bowls, wind chimes, serving trays and jewellery. Incorporate the use of ceramic moulds so the glass fuses into the shape of the mould. Making fused glass is simple, eco-friendly and profitable. Fused glass makes great gifts for friends and relatives, and sells well at craft shows, fairs, trade shows and online.

Paint three coats of kiln wash on the floor of the kiln, the kiln shelf and the slump mould. Let the kiln wash dry overnight.

Vacuum the kiln. Remove all ceramic dust from the kiln. It sticks in hot glass, ruining the design.

Place the slump mould on top of the kiln shelf. Do not put the shelf in the kiln until the glass is arranged on the mould. You may need a second person for help putting the shelf into the kiln without dumping off the glass.

Center the glass sheet over the slump mould, and set it on top of the mould. Place different colours of broken glass around the glass sheet. If you want small pieces of glass, place the glass into a cloth pillowcase, and hit it with a hammer. It doesn't matter how the glass is broken, as long as the size works in your design. If you want to purchase a glass cutter and cut the glass, it works fine, but breaking it with a hammer is easier and faster.

Put the kiln shelf with the slump mould and glass into the bottom of the kiln. Make sure your design didn't slide as it went in the kiln. If it did, push it back into position.

Close the lid on the kiln, and turn the kiln on low for one hour, or set the temperature to 260 degrees C. This warms the glass before fusing.

Turn the heat on high for three hours, or set the temperature control to 815 degrees C. Once it reaches 815 degrees C, the glass is fused, and ready.

Cut off the kiln, and let it sit unopened overnight. The kiln needs to cool slowly for the glass to anneal (harden) properly.

Remove the kiln mould from the kiln, and pull the glass out of the mould. Wash off any residue with a stiff brush and water.


Some people set the kiln for 593 or 635 degrees C, and let the glass sit at that temperature for one hour before going up to 815 degrees C. It is an unnecessary step. The glass fuses perfectly without this added step.

Things You'll Need

  • Ceramic slump mould
  • Sheet of glass 2 inches wider than the mould
  • Assorted coloured glass pieces
  • Kiln wash
  • Paint brush
  • Kiln shelf
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