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Hello - I am a glass blower and am about to begin some experimenting with small fused pieces. Specifically I will be seeking to make flat shallow cavity molded patterns in a suitable mold material, by carving the pattern, ant then fuse frit mixtures into them so I can pick them up later and incorporate them into blown glass work. The patterns may be complex in design, but will be 2 dimensional and likely about 1/16th to 1/8inch thick.

Having not worked with high temp mold materials before, I would be grateful for a recommendation on a preferred mold material to use for this application - I will want to carve the impressions into the flat upper face of the mold material and would like to also be able to make many copies without the cavity breaking down too fast.

Thanks in advance, Dan B, Seattle

How about just using clay? Pretty durable, easy to carve if you let it dry up some before you start. Pattern will shrink some as it dries but this may not be a problem. Just be careful with undercuts.

Just my 0.02 euros:

Clay is good. I am afraid of red or other colored clays. The oxides may discolor the glass.

I cast larger relief panels, like 10"x20". Therefore I use a clay with 25 % chamotte in it. Increases heat tolerance. I bisquit fire the molds to 1000 C. Before bisquit firing I cover it with kiln wash.

-lauri

Question... should you put kiln wash on a piece of class before you fire it to bisque?

English is not my native question and I do not understand yor question.

When the _clay mold_ is bone dry, I cover it with the first layer of kiln wash. After bisquit firing I add a second layer of kiln wash before putting the glass in. In frit casting I do
not prefire the second kiln wash. When slumping large sheets the risk of trapping gasses is greater and I recommend pre-firing.

-lauri