How are coefficients of expansion used in the manipulation of glazes?

Unit 7 Topic 18
Using Unity Formula

The coefficient of expansion is used for comparing the tendency for glazes to craze if they were to be fired on the same clay body, applied similarly, and fired in the same firing conditions.
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When various glazes are fired on samples of the same clay body in identical firing conditions, the degree of crazing which results may vary. Some, in fact, may not craze at all.

The calculated coefficient of expansion for each of these glazes would reflect the degree of crazing which eventuates.

If one of these glazes is found to 'fit' the clay body on which it was tested its coefficient of expansion should be noted.

This value can then be used as a crazing benchmark when assessing the tendency for other unfired glazes to craze if they were to be fired on the same clay body under similar firing conditions.

Each clay body will have its own benchmark for crazing. A glaze which crazes on one body may not craze on another.

It must be emphasized that comparing glazes for their tendency to craze only valid if those glazes were to be fired on the same clay body to the same temperature with the same firing cycle.
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