Finding a Crazing Benchmark
a number of glazes on a particular clay body under similar application and firing
conditions, they can be examined for crazing to determine how low
the coefficient of expansion must be for crazing to disappear.
value may then be considered as a "crazing benchmark" for that clay
body, application and firing conditions.
after firing a number of glazes on the same body at the same temperature,
you find some of the glazes have not crazed. Next check out the
coefficients of expansion for those glazes using glaze calculation
software. You may find that the values for the glazes that have
not crazed might average say 7.5 (depending on what expansion factors
your software uses). This value of 7.5 becomes your guide for glazes
on the same clay body, applied similarly and fired at that temperature. You can use it to check
unfired glazes for their potential to craze and you can also use
it to change glazes to reduce (or increase) crazing.