ivor and olive lewis on fri 18 nov 11
Dear Liz Gowan.
Relying on Hamer's section on cracks and their resolution it would seem tha=
t
changes to your clay have resulted in it either
A, Your new clay is short.
B.. Your Rims which are to thin to carry transferred stress. Compressing
them may help to give greater strength .
C .Rapid drying at the rim
Hair line cracks in raw clay may only become apparent during firing.
I suggest you read what Hamer has to say.in his potters Dictionary.
Regards,
Ivor Lewis,
REDHILL,
South Australia
Liz Gowen 1 on fri 18 nov 11
Thanks Ivor, I tend to forget about Hammer. Just a follow-up: I called
Standard and they are sending some white bentonite out to add to the
porcelain I have. It has no ball clay only grolleg porcelain. They are also
sending a block of porcelain from a different run which I will throw the
same forms with and see if it is better. I find I cannot turn these pots on
their rims at all or they crack, all of them. I am trimming them suspended
over foam this time and so far they have survived. I do compress the rim an=
d
have tried to thicken it a bit. I only carved one in this group. Will repor=
t
back when I throw the new clay and or add the bentonite. Thanks for
everyone's input. ..Liz Gowen
-----Original Message-----
From: Clayart [mailto:Clayart@LSV.CERAMICS.ORG] On Behalf Of ivor and olive
lewis
Sent: Friday, November 18, 2011 12:47 AM
To: Clayart@LSV.CERAMICS.ORG
Subject: Bowl Cracks.
Dear Liz Gowan.
Relying on Hamer's section on cracks and their resolution it would seem tha=
t
changes to your clay have resulted in it either A, Your new clay is short.
B.. Your Rims which are to thin to carry transferred stress. Compressing
them may help to give greater strength .
C .Rapid drying at the rim
Hair line cracks in raw clay may only become apparent during firing.
I suggest you read what Hamer has to say.in his potters Dictionary.
Regards,
Ivor Lewis,
REDHILL,
South Australia
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