What happens when engobe fired shrinkage is too high?

Monday 14th May 2018

The white insight-live.com/glossary/35">engobe on the inside of this mug does not fit, that is what these cracks are about. The misfit can be demonstrated using EBCT test bars (shown in the foreground). This pair sandwich the engobe and body as a bi-clay strip, they are dried and fired with alternative sides up. A bend demonstrates differences in the fired shrinkage of body and engobe. On drying these stayed relatively flat but after firing at cone 10R, the engobe's higher shrinkage pulled them concave. On this mug, made from the same clay and engobe, the latter has done likewise, shrinking more than the body and creating a crack pattern that even the glaze could not hide. This was a development version of L3954N that contained too much nepheline syenite.

Pages that reference this post in the Digitalfire Reference Library:

EBCT Engobe Body Compatibility Test, Engobe

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