Why want it slump?
Moderators: Brad Walker, Tony Smith
Why want it slump?
I put one piece of glass, not the heat glass just regural glass, in the kiln and it didn't slump in the mold. Won't regural glass slump or does it need to be hotter to slump. there are just so many beautiful glass it seems a shame not to try a few.
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Tony Smith
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Do you mean window glass (float glass) when you refer to "regular glass"? If so, you will find that it slumps at higher temperatures than art glass. Keep raising the temperature until it starts to move, then hold until it's fully settled in the mold.
Tony
Tony
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Brad Walker
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Brad Walker
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Actually, it's a strange firing schedule and I'm not sure I understand the logic behind it either. Nevertheless, if a soak of 15 minutes at 1225 didn't work, then I would soak for longer at that temperature.
In general, you need to know the type of glass, the thickness and size of the glass, and the type of mold in order to select a proper firing schedule. The type of mold is especially critical, because different molds require different amounts of heat to slump properly. Small molds generally take longer soaks or higher temperatures (or both!) than big ones.
In general art glass will slump between 1100 and 1300 F, after a soak of 0 to even 60 minutes or more. It all depends on the factors I mentioned in the previous paragraph. But the critical thing to know about slumping is that if you're inexperienced with the particular slump you're trying you need to watch the glass carefully to learn how it will behave. And don't be afraid to slump for a longer period of time if necessary.
In general, you need to know the type of glass, the thickness and size of the glass, and the type of mold in order to select a proper firing schedule. The type of mold is especially critical, because different molds require different amounts of heat to slump properly. Small molds generally take longer soaks or higher temperatures (or both!) than big ones.
In general art glass will slump between 1100 and 1300 F, after a soak of 0 to even 60 minutes or more. It all depends on the factors I mentioned in the previous paragraph. But the critical thing to know about slumping is that if you're inexperienced with the particular slump you're trying you need to watch the glass carefully to learn how it will behave. And don't be afraid to slump for a longer period of time if necessary.
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Lynne Chappell
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If the stained glass is Spectrum, then it should slump at 1225 if the mold is a decent size. If it is Kokomo, Wissmach, Armstrong, then you might have to go higher. Some of them devitrify (get scummy on the surface) even at those low temperatures and then they don't slump well.
I have found that some factory programs don't go hot enough for small molds (or get there too quickly for the heat to do it's work). Change the process temperature to 1275 and see if that does the trick. I can't tell you exactly how to do that as I haven't used that particular controller, but I think you hit the up arrows and it goes up 10 degrees at a time, or something like that. The manual should tell you how.
I have found that some factory programs don't go hot enough for small molds (or get there too quickly for the heat to do it's work). Change the process temperature to 1275 and see if that does the trick. I can't tell you exactly how to do that as I haven't used that particular controller, but I think you hit the up arrows and it goes up 10 degrees at a time, or something like that. The manual should tell you how.