A family member, thinking they were doing a good thing, bought me two molds for slumping, however they got them from a ceramics store. They are labeled as "White Ware from Laguna Clay. Can I use these for glass? They are both marked on the bottom not to fire at a ramp rate greater than 250 C per hour, much less than the typical rate I use. I have tried some of the ceramics forums, but no answers there.
Thanks for any help.
White Ware
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i think that they mean not to go fast through quartz inversion temps. we are generally going full on at around 1150f. darn i wish i could remember the exact number. anyhow i have broken molds going fast there. rosanna.......ok i looked it up, quartz inversion happens at 573c or 1064f. i go slowly through those temps as a favor to my kiln brick and furniture. i hold at 1150f or so for evinivity, then blast off. google quartz inversion sometime. it is a good read.
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White Ware
Sorry, I meant 250 F, not C. I typically ramp at ~400 F/hr, hold for a few minutes and then up AFAP to ~1300.
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White Ware
I've slumped a variety of types of glass; Bullseye, Spectrum (standard and System 96), & Gecko, 2 inches to 22 inches in diameter and as many as three layers. So far have never had any breakage.
I use profiles suggested by Spectrum as the starting point for all of my work. For System 96, a piece 12 inches and 2-3 layers they recommend a ramp rate of 400 F per hour. Even for larger pieces, where I would ramp in three stages, the slowest rate is 400 F per hour.
I use profiles suggested by Spectrum as the starting point for all of my work. For System 96, a piece 12 inches and 2-3 layers they recommend a ramp rate of 400 F per hour. Even for larger pieces, where I would ramp in three stages, the slowest rate is 400 F per hour.