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Old 10-07-2019, 07:36 AM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 21,933
Pete VanderLaan is on a distinguished road
300C is the gold standard. I would note that the testing I've done has been from 19C though. Getting your samples to stay at 0C is quite the chore. When Los Alamos labs did the testing of my dilatometer with me back in the late '90's, we did ice water baths with magnetic stirrers to try to get the tooling down to 0C and the numbers never made sense. It wasn't until the temperature that people in lab coats like to work in that we tried 19C and it all worked well and made sense. It's an important observation in that the testing Winkleman and Schott did for the enamel industry only went to 200C which was why the combination of those numbers with the English and Turner numbers failed. It's really the case now that the Appen figures are the best.

The dilatometer is not used much in the studio. John doesn't use it and I tend to if I know absolutely nothing about the glass in question. Otherwise the Hagy seal and the ring test provide excellent comparative numbers, one through gaps and the other through tension. Both ring and Hagy are problematic if the test glasses are off by much. They break. My goal in any test is to have all the indicators pointing in the same direction.

At that point viscosity becomes an important factor. The piece in question is I'm sure chock full of different ones.
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