Thrown pieces made from pure Grolleg and EP Kaolin

Sunday 24th June 2018

These have just been thrown on the wheel. They were slurried and dewatered to about the same water content and the same amount was thrown on a potters wheel to compare the plasticity. While the Grolleg is stickier and dewaters a little slower, it is not nearly as plastic. Curiously, New Zealand Halloysite is quite a bit less plastic than the Grolleg but it responds to plasticity augmentation (in porcelain recipes) just as well as Grolleg (similar amounts of bentonite producing similar plasticities). And, bodies containing EPK need about the same amount of bentonite to produce plasticity suitable for throwing large forms. So, the plasticity a porcelain appears to have by itself is not completely indicative of what it will contribute to a body.

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EPK fired bar (top) vs Grolleg at cone 10R. Why shrinking more?

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