Frit Casting

Frit casting is one of the simplest glass casting methods. It does not require special casting molds. Any fusing mold will work for this process. Prepare the mold with a separator or kiln wash before beginning the procedure.

Frit compacts as it becomes molten in the kiln. As the frit is heated up inside a kiln, all the tiny air spaces are filled with the melted glass. Since it settles down into the mold, the process may take several firings depending on the outcome you wish to achieve.

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Keep in mind that the larger the frit used the more it will melt down into the mold. So it makes sense to use smaller pieces of frit for less compacting.

Firing the casting is basically the same as normal glass fusing. It is customary to heat up the glass at about 300 degrees per hour and hold the piece at about 1200 degrees Fahrenheit for about 30 minutes. After that the piece can be taken up as fast as possible until the full temperature is reached. Once you have reached a full fuse, soak the piece for a period of time depending on the size of the piece that is being fired.

There are a few ways to accomplish obtaining a full mold of glass when doing frit casting.

1. The easiest way to obtain a full mold is to allow the first firing to transpire and then refill the mold and heat the glass up again. This may take several firings until the mold is completely full.

2. Another way to accomplish a full mold is to build up the frit so that when it settles down it fills the mold. This method may require that you build up an access of frit onto the mold before firing.

3. The final way to obtain a full mold would be to add more glass while the kiln is still hot. When the frit has settled down inside the mold more frit can be added to the piece. This approach requires that you reach inside a torrid kiln, so high temperature gloves, IR/IV eyewear is necessary, and of course safety precautions. Turn off the kiln before adding more glass to avoid getting shocked. Since frit is tiny pieces of glass, there is no problem with thermal shock.

Before beginning your procedure, you will want to know how much glass is needed to fill the mold completely. You can estimate the required glass.

  • Fill a cup or glass with water.
  • Mark the water line on the container.
  • Pour water from the container into the designated mold until the mold is full.
  • Now fill the container with the designated glass frit until the water level reaches the mark line.
  • The amount of frit required to reach the line should be the amount needed to fill the mold when fired.

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