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need advice on large tiles cracking

updated fri 15 oct 04

 

Pat Logue on thu 14 oct 04


Hi folks
I've got a problem, not sure whats happening.
I'm pressing large round tile, about 15 " dia., 3/4 " thick. using
Standard ceramics 547 sculpture clay.
I have a home made press that puts about 12 tons of pressure on the mold.
The problem im having is that in the glaze firing some of them are
splitting right in half ( i assume with some force because the pieces
are usually a couple of inches apart whan i unload). My losses are
running at about 25-30%
Anybody have any suggestions?
Pat