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Old 04-14-2019, 05:55 PM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 22,276
Pete VanderLaan is on a distinguished road
yet you would attribute the effects of Lithium at a .5% level as being a likely suspect in the tendency for SP 87 to devitrify in a fixed temp range. Many glasses will devitrify in cold spots in large furnaces as I've always understood it. If, as you and I looked at, a few weeks back that SP87 has in fact had variations and the one we poked at listed the Li content at 1%, not .5%, we're both clear about where Tom finally landed but I'm still looking for this feature of lithium, beyond the radius which would have such an effect.

I left lithium out of my formulation for Tom but that was based in the suspicion of price and availability of the stuff. Beyond those additives, I tried to stay true to Tom's formula where I could and decided instead to use nitrates to drive melt characteristics down. I can assure you, mine does not even hint at devit, slumps readily and doesn't attack a 90% alumina refractory. Pretty cool. I would be interested in your thoughts on the two glass differences as to Devit. You have both formulas.
Where are we going and why am I in this basket?
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