How to Make Glass Molds

Make your own molds for glass casting.

Firing your own glass masterpiece in a kiln is rewarding. But, typically, much work is involved in bringing the final piece of art to completion, based upon making the mold for casting the glass. The good news is there are commercially manufactured mold mixes available that work much like cement mixes. Simply add water and create a mold for your desired master item. Create custom gifts and decorative pieces following a few simple steps.

Things You'll Need

• Mold mix
• Rubber gloves
• Master mold or mold model
• Mold release agent or olive oil
• Paper towels
• Kiln

Instructions

1. Determine the volume of mold mix you need for your mold, following the manufacturer's package instructions.

2. Prepare the master mold, which is the item you are using for the mold model. Clean any dirt and debris from the surface, using a paper towel and water. Apply a mold release agent or a thin coating of olive oil to the surface, using a clean paper towel.

3. Add water to the mold mix, according to the manufacturer's directions. Add water slowly to the mix until it reaches the consistency of loose cement, if you are pouring the blend. Add water slowly until the mixture can be tossed gently, yet hold together, if you are layering or molding the mix to the master mold. Mix the blend for five minutes.

4. Fill or cover the master mold with the mold mix, ensuring all surfaces are covered. Tap the mold to remove air bubbles from the surface, if pouring the mixture. You typically have 20 minutes to work the mix before it starts to set up.

5. Cover the mold with plastic wrap and allow it to harden for 24 hours.

6. Remove the plastic cover and gently pull the master mold from the casting mold, following the mold mix manufacturer's instructions, before curing the mold in the kiln.

7. Place the mold in a kiln at a temperature level of 40 degrees/hour set to reach 225 degrees Fahrenheit and hold at that temperature for two hours to drive out moisture.

8. Increase the kiln's temperature to 55 degrees/hour to reach 400 degrees Fahrenheit and hold at that temperature for one hour to ensure a dry casting.

9. Increase the kiln's temperature to 75 degrees/hour to reach 1,400 degrees Fahrenheit and hold at that temperature for one minute for final heating and burnout.

10. Turn off the kiln and allow the mold to thoroughly cool before using.

Tips & Warnings

• Store molds in a dry spot. Make sure the mold is completely cool before storing.

• Avoid stacking molds. Place a piece of cardboard between each mold, if you do stack them.

• Use an airtight master mold or mold model. Water may be lost during the hardening process because of a leaky master mold, resulting in a crumbly mold.

References

• Glass Fusing Made Easy: Making Fusing Mold
• Glass Campus: Molds
• Mold Mixes: Mold Materials
• Blick: Amaco Glass Casting Mix