How to Make Fusing Molds

You can use high-fire clay to make a glass fusing mold.

High-fire clay is an ideal material for glass fusing molds since it's durable, inexpensive and versatile. Once fired into ceramic, the clay mold will be reusable. Kiln wash or glass separator will be applied to the mold to prevent the glass from sticking. Fused glass is commonly used to create jewelry, sculptures and other glass art. The fusing mold serves to contain the glass, which will be malleable and slightly runny when heated in the kiln. The mold can also be used to give form to the glass. The glass will sink into the depressions, creating a raised "positive" version of the carving or stamping design.

Things You'll Need

• High-fire clay
• Scrub pads
• Kiln
• Water
• Kiln wash or glass separator
• Medium paintbrush

Instructions

1. Form the clay into the desired shape. Include a little hill around the perimeter of the mold to contain the glass within the mold.

2. Dry the clay mold until it's a leather hard. Refine the mold shape and smooth the mold surface using a scrub pad.

3. Dry the clay mold until it reaches a bone dry state. This can take two to five days, depending on temperature and humidity.

4. Load the mold into the kiln and perform a bisque firing.

5. Remove the cooled fusing mold from the kiln and rinse it to remove dust and debris.

6. Apply a coat of kiln wash or glass separator to the mold. Apply kiln wash or glass separator to all regions that will contact the glass.

7. Place glass inside the mold and perform a glass fusing firing.

Tips & Warnings

• Kiln wash may stick to the bottom of the fused glass piece. Remove it with a fine wire brush or steel wool.

• Apply fresh kiln wash or glass separator to the mold prior to each firing.

• The clay mold must be approximately 10 percent larger than the desired mold size because the clay will shrink as it loses moisture during the firing. Consult the product packaging for information on the precise percentage of shrinkage.

• Fire the fusing mold at a temperature that's significantly higher than the temperatures used for glass sagging and fusing.

• Do not remove a filled fusing mold from the kiln until it's cool to the touch. The glass and mold may crack due to thermal shock.

References

• American Glass Supply: Glass Firing