Cone 6 kaolin porcelain verses ball clay porcelain.

Friday 6th March 2015

Typical porcelains are made using clay (for workability), feldspar (for fired maturity) and silica (for structural integrity and glaze fit). These cone 6 test bars demonstrate the fired color difference between using kaolin (top) and ball clay (bottom). The top one employs #6 Tile super plastic kaolin, but even with this it still needs a 3% bentonite addition for plasticity. The bottom one uses Old Hickory #5 and M23, these are very clean ball clays but still nowhere near the whiteness of kaolins. Plus, 1% bentonite was still needed to get adequate plasticity for throwing. Which is better? For workability and drying, the bottom one is much better. For fired appearance, the top one.

Pages that reference this post in the Digitalfire Reference Database:

Kaolin, Ball Clay, Bentonite, Maturity, Porcelain

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