Thermal shock failure in raw ball clay much worse than the 100 mesh material

Wednesday 27th July 2016

The cup on the left is raw, unground, ball clay (Plainsman A2 fired to cone 10 reduction). It cracked under a flame in only 4 seconds. The 200 mesh version on the right lasted 14 seconds (it is broken because I dropped it). It would appear that the larger quartz particles in the material on the left are imparting much less resistance to thermal shock failure.

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Thermal shock, Quartz Inversion

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