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small pots crack, big ones do not.....

updated tue 30 sep 08

 

Paul Borian on mon 29 sep 08


Right now I am having problems with the smallest pots I make cracking.
My berry bowls come with little 6" plates and my chip and dips come with
little bowls, and both those items have been cracking constantly. I
thought it was due to the a/c in my studio but I have since turned it
off for the year and the cracks continue. These kinds of pots are the
only ones with a lot of cracking though - not plates, platters or
anything really.

All the other bowls I make have foot rings carved into them and they
never crack. So I know I could foot all these dip bowls to avoid the
problem but I still would like to know why they crack, especially
because there are lots of other items I make that do not have foot rings
and they don't crack either.

I suspect that it is basically because they are such small items that it
causes them to dry much faster, especially during the initial stage of
drying right after they come off the wheel ( and I believe this phase is
the most critical to control when trying to avoid cracking because
shrinkage is greatest during this time).

Also, does anyone have a technical explanation of why footed pots almost
never get s-cracks? It has been several years since I have seen a crack
in a footed pot - and I don't always do such a good job controlling the
drying on them either (sometimes the rims are bone dry by the time I
flip them).

Any info appreciated!

=20

Thanks,

Paul

James F on mon 29 sep 08


Paul...

Are you doing anything differently when throwing the small versus the large=
r pots? Perhaps throwing the small pots off the hump?

...James

> Date: Mon=2C 29 Sep 2008 13:04:02 -0400
> From: Paul@DOCRET.COM
> Subject: Small pots crack=2C big ones do not.....
> To: CLAYART@LSV.CERAMICS.ORG
>=20
> Right now I am having problems with the smallest pots I make cracking.
> My berry bowls come with little 6" plates and my chip and dips come with
> little bowls=2C and both those items have been cracking constantly. I
> thought it was due to the a/c in my studio but I have since turned it
> off for the year and the cracks continue. These kinds of pots are the
> only ones with a lot of cracking though - not plates=2C platters or
> anything really.
>=20


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