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cracking tiles/ more specific

updated mon 27 aug 01

 

Doug Gray on sun 26 aug 01


I received this response off the list, but thought it warranted
posting. It comes from Tom Herdon, fellow clay bud and good friend (and
experienced clay artist, though he wouldn't admit it to you). Tom works
with a variety of methods, but in this particular case he is referring
to slip casting. He brings up a good point about shrinkage and timing.
Hope you don't mind, Tom.

Howdy Doug,

Sometimes the piece can crack before
it's ever removed from the mold. A co-worker wandered off once & forgot
a
piece in the mold. When we did eventually discover it, it was bone dry &
had
a death grip on the mold. We pried it out of there to discover that it
had
torn itself apart, shrinking smaller than the mold would allow.

Granted, we're not press molding, but the mechanics are similar. Who is
to
say at what point in the drying process an unforgiving mold begins to
weaken
the piece?

Fortunately our turn around is such that we can spot the trouble area(s)
on a
piece & react accordingly: a wire tool drawn along the weakened area to
re-compress the clay before leather hard is usually enough.

Pinches,
Tom