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Old 07-13-2002, 07:58 AM
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Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 21,968
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Originally posted by Mitcheal Veenstra
Hey Pete, and any others that might know...

I had an email conversation a long time ago with a glassblower that built his own electric wire furnaces. He always melted around 2150 with a long soak and squeez to fine out.

He said it tended to make the sp87 somewhat softer.. he'd have some compatibility fit problems. But nothing to bad...

Any idea why this happens? Or does this even happen?

There is less sodium ionization at colder temps causing sodium retention. I have demonstrated and tracked the changes in expansion based on temperature in a variety f batches over the years. SP87 produces a 96 based on melting at 2323 F. If you melt hottter, it goers down, colder and it goes up. I have sucessfully moved it over a range of 94-98. Quite a spread.
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