Calcium carbonate and glaze bubbles


Wednesday 19th March 2014

The two insight-live.com/glossary/119">cone 04 glazes on the right have the same chemistry but the center one sources it's CaO from 12% calcium carbonate and ulexite (the other from Gerstley Borate). The glaze on the far left? It is almost bubble free yet it has 27% calcium carbonate. Why? It is fired to cone 6. At lower temperatures carbonates and hydrates (in body and glaze) are more likely to form gas bubbles because that is where they are decomposing (into the oxides that stay around and build the glass and the ones that are escaping as a gas). By cone 6 the bubbles have had lots of time to clear.

Pages that reference this post in the Digitalfire Reference Library:

Calcium Carbonate, Decomposition, Glaze Bubbles


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