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Old 03-31-2005, 07:30 AM
Lani McGregor
Posts: n/a
Re: origin of COE - yeah, but WHICH one?

Originally posted by Bruce Troeh
While Iowa State still has the glass facility it no longer offers glassblowing except through the Glasblowers Guild. I started in 1977 learnign (sp) about formulating batch and calculating COE with Dr. David Martin. At the time I remember one of the grad students had purchased a box of kugler color I dearly wanted to use. Our batch was 111 - 113 COE. I do remeber a few broken pieces.
I've got a box of kugler to play with now but I'm using 104 so it still sits. BTW. Bruce
But these were theoretical CALCULATIONS, yes? Did you ever MEASURE the COE back then? I.e., with a dilatometer?

This is definitely the basis of a lot of the confusion: the difference between calculated and measured COEs. The imagined compatibility between glasses of the same expansion in today's studio/marketplace is based on comparing MEASURED expansions.

And what I'm digging for is WHEN did the measured COE become the standard for compatibility in studio glass?
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