Cone 04 terra cotta cross section close-up with glaze

Monday 15th June 2015

The glaze is well melted, but the interfacial zone with the body is very narrow. It is basically just stuck on the surface. The body is not developing any clearly visible glassy phases as does porcelain and stoneware, so not surprisingly, its strength is much lower than vitrified clay bodies at higher temperatures. However it is possible to add a frit and glass-bond the particles at cone 02 (at much higher cost of course). Not surprisingly, glazes must be more closely tuned to match the thermal expansion of the body for lower temperatures (since they are not stuck on as well).

Pages that reference this post in the Digitalfire Reference Database:

Terra cotta, Porosity, Vitrification

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