Firing Clay

There are many directions in firing clay. Whether you have used the freeze and fuse method, or free-hand created your master piece, the glass clay needs to be fired to complete the process.

Before firing the clay the material needs to be thoroughly dry. This can be achieved by leaving the pieces out for a couple of days, while rotating from front to back to allow the clay to dry, or by using a hairdryer or food dehydrator to speed up the drying time.

When first experimenting with this substance it is suggested that you start with lower temperatures. The clay can be fired again if you want to acquire a different finish. The claim is that the clay actually gets stronger the more often it is fused.

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During the firing process, the material will shrink. How much shrinkage occurs depends on the temperature reached and any hold times. Expect shrinkage of about 25-30% from drying and firing the matter.

You will attain different finishes depending on the temperature reached and how long the glass was held at various temperatures. None of the information I have read indicates that the clay should be fired any higher than 1325 degrees Fahrenheit.

Some individuals suggest that you vent the kiln until the temperature reaches about 1050 degrees Fahrenheit, while other instructions don’t indicate that this is necessary. I chose the latter and did not vent my kiln during the firing of all of my pieces.

This is the schedule I used in my programmable kiln for all of the pieces, and as you can see they came out with different textures even though the firing was the same. I think this maybe because of the various materials and binders used to assemble the clay.

The following Firing Clay schedule is only a guide:

Phase 1 - Bring the temperature up as fast as possible to 180 degrees Fahrenheit and hold at this temperature for about an hour.

Phase 2 – Raise the temperature 600 degrees per hour to 1000 degrees Fahrenheit and hold at this temperature for about 30 minutes.

Phase 3 – Raise the temperature at about 600 degrees per hour to 1300 degrees Fahrenheit and hold at this temperature for about 20 minutes.

Phase 4 – Bring the temperature down as fast as possible to 950 degrees Fahrenheit and hold for about an hour.

Phase 5 – Lower the temperature 150 degrees per hour to 700 degrees Fahrenheit.

Phase 6 – Shut off kiln and allow the temperature to cool to room temperature.

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