[PA-NJ Glassblowers] Compatibility of Glasses - COE Does Not Equal Compatibility
Tony Patti
gaffer at glassblower.info
Wed Mar 6 20:43:26 EST 2013
http://www.bullseyeglass.com/images/stories/bullseye/PDF/TechNotes/technotes
_03.pdf
Bullseye president Dan Schwoerer has updated Technotes 3: Compatibility of
Glasses,
his influential 1997 paper with new information specifically for kiln-glass
practitioners.
If you've ever had questions about Measured COE, Calculated COE, viscosity,
or other aspects related to compatibility, Technotes 3 is a must-read.
A misunderstanding that the compatibility or "fit" of two glasses is solely
a function of their expansion properties has led to an overemphasis on
"expansion" and the numerical value of the coefficient of expansion (COE) of
glass. Studio artists continually ask us for the COE of a glass, hoping to
predict whether it will "fit" other fusing glasses or their own furnace
glass. We say the same thing each time: Matching COEs is simply not an
accurate measure of compatibility.
The viscosity characteristics of a glass are equally important as its
expansion characteristics. Together, these two properties determine whether
one glass will fit another. But it will be useful to first discuss each
individually as it pertains to this subject.
Tony Patti
<http://www.glassblower.info> www.glassblower.info
<mailto:gaffer at glassblower.info> gaffer at glassblower.info
<http://www.glassblower.info/qr-code.html> QR Code for Tony Patti -
www.glassblower.info
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