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Old 08-25-2020, 11:52 PM
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Originally Posted by Marty Kremer View Post
Does plaster contribute to devit?
I get devit going too slow through the 1300's and also (sometimes) from unifrax fiberpaper binder fumes.
The answer is yes, but not because of the plaster itself, per se. As you pointed out with the binder fumes it has more to do with with the off-gassing of materials. Chemical water in plaster investment can take a long time to burn out depending on several variables. How thick is the mold? How long did it soak at temp.? If you ramp up really fast to your casting temp. there may not be enough time for the water to dissipate before your glass starts to soften. Then you're in the devit range temp.-wise, so it's a perfect storm-type scenario.
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