View Single Post
Old 09-30-2019, 03:51 PM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 22,171
Pete VanderLaan is on a distinguished road
The grinding really messes with the surface tension of the glass. Pieces that would hold together for long perids of time will break up rapidly once the grind is done.

That's true of taking Kugler opaques and working them with SP87. If you grind them they will more often than not, fail. Spruce Pine made the SP83 specifically to match the kugler opaques which all hover around an 88-89. The opaque reds and yellows are more like an 85 and since those colors do not contain any lead, they are far more sensitive to mismatch.

Cristalica is measurable at between 96.8 and 97+, making it higher than SP87. Any of these glasses that haven't broken, in my mind, haven't broken yet. I tend to think that much of the glass made since 1970 or so won't be here for all that long.
Where are we going and why am I in this basket?
Reply With Quote