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Old 06-06-2018, 07:46 AM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
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Pete VanderLaan is on a distinguished road
My clear and also my unoxidized batch glasses are a 96. Cristalica is a 97.0. My older unoxidized formula was as I recall in the mid 95's.

The memory of the dilatometer is reasonable short of the brass fitting into which the gauge slips into and gets screwed down. I would not say it was cheap to build nor would I say it's foolproof. It's a tool. It required a very tight kiln to measure in if you recall Eben and without it ( A tubing annealer) it would be a rough go to get tight numbers. It also requires a handheld temperature measuring device. If you recall, I had an omega unit to read the kiln. The test sample in fact was 4mm x 4.000. In all of these tests, they point in a direction. None are foolproof. The goal is to have all the indicators pointing in the same direction. They are the Hagy Seal, the ring test , the pull test and the dilatometer. Doing all of the tests requires experience. If you send material to Corning for testing, They will tell you to always ask for the same technician you have been using. There's a reason for that.

Using Dave's early stuff before the strontium as I recall did use calcium and had the subsequent apatite crystals. Cristalica is an outlier as an expansion. I encouraged Kuchinke to lower that expansion a half point but those guys really never wanted to hear from me about changes in the goop. Switching to mostly strontium did improve things vastly. I think using such things as 20 mule team borax may be a mistake, it does seem to have other things in it. I am going to have Jim mix the stuff for whoever wants it in the west and it will be decidedly different than Cristalica. Melting in a wire melter is not something I've tried.
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