The coefficient of expansion reflects the amount of crazing which
might be expected of a glaze when fired on a particular clay body
in certain firing conditions.
Each oxide in
a unity formula has a unique expansion factor allocated to by researchers
who have studied and measured the degree to which oxides contribute
to the overall expansion of a glaze melt.
As several ceramists
have studied glaze expansion there are several different sets of
factors which may be used and each of these sets has been named
after their originators.
glaze technologists have their own preferences, it does not really
matter whose expansion factors are used. It is important to use
only one set as the factors are not interchangeable.