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Old 05-17-2019, 09:46 AM
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Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 22,193
Pete VanderLaan is on a distinguished road
While I don't have the recipe John wanted to use , it will be the case that calcium will cause a lot of issues from the SP. The new silica is remarkable in its clarity if the stuff you purchased is in fact new stock.

Phosphates don't do well if cooled down much. That's true of a lot of glasses. I tend to think the lumps in lead arsenates are caused by overcooling the melts to make rods. In general, glass doesn't want to be in a rod form anyways. The attempts we made up here with Marks TIT series turned to glasscrete when cooled. We kept the calcium out of those glasses and replaced with Strontium.
Where are we going and why am I in this basket?
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