Gillian Poulter on tue 24 feb 98
I'm wondering, is there any rule of thumb when dealing with coefficient
of thermal expansion numbers? If you know the body has a certain
coefficient, lets say 7.25, how much play is there in the glaze's
coefficient of thermal expansion on either side of this number before
one develops crazing or shivering? In addition, how much compression is
desirable for a good fit between body and glaze? I realize testing is
the best way to find the answer to a glaze fit problem. Just thought
perhaps that those of you having used the new ceramic glaze programs, in
addition to testing, might have developed limits with regard to
expansion numbers.
Les Wright
poulterg@yorku.ca
Tony Hansen on thu 26 feb 98
>I'm wondering, is there any rule of thumb when dealing with coefficient
>of thermal expansion numbers? If you know the body has a certain
>coefficient, lets say 7.25, how much play is there in the glaze's
>coefficient of thermal expansion on either side of this number before
>one develops crazing or shivering? In addition, how much compression is
>desirable for a good fit between body and glaze? I realize testing is
>the best way to find the answer to a glaze fit problem. Just thought
>perhaps that those of you having used the new ceramic glaze programs, in
>addition to testing, might have developed limits with regard to
>expansion numbers.
Sometimes I wonder whether we have created a monster with this expansion
calculation thing. I know it works and I use the system all the time
but I think we all need to appreciate that it is a general guide only.
It gives direction but the burden of determining a glaze's suitability
must be entirely on testing.
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T o n y H a n s e n thansen@digitalfire.com
Get INSIGHT, Magic of Fire at http://digitalfire.com
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