David Hendley on sat 16 jun 01
Dear Ivor, I don't know if this is a question you don't wish to answer, but
I would be interested in knowing what your 'simple experiments'
concerning the release of carbon dioxide were.
I think that there are several factors at play that cause S-cracks, and this
may well be a contributing force.
David Hendley
Maydelle, Texas
hendley@tyler.net
http://www.farmpots.com
----- Original Message -----
From: "iandol"
To:
Sent: Saturday, June 16, 2001 11:34 AM
Subject: "S" Crack Initiation.
Realising that my Detractors and Critics are about toget out their shovels
and have a field day, I offer the following short note for those who are
interested in this topic to think about.
Having reviewed such relevant literature as I can find and conducted some
simple experiments which provided enlightening observations I have formed an
opinion that Carbon dioxide, released as a free gas which collects along
shear planes (caused by pug milling, wedging, kneading or other plastic clay
forming processes) in flock structures, provides a trigger mechanism which
initiates cracks under conditions of high drying stress.
It is not my intention to explain this on Clayart or to answer questions but
comments would be appreciated.
Best regards,
Ivor Lewis. Redhill, South Australia.
weaver on sun 17 jun 01
My teacher told me that "S" cracks are from allowing too much water to
accumulate in the bottom of the pot while throwing. She has us
constantly mopping it out with a sponge.
Forest
iandol on sun 17 jun 01
Realising that my Detractors and Critics are about toget out their =
shovels and have a field day, I offer the following short note for those =
who are interested in this topic to think about.
Having reviewed such relevant literature as I can find and conducted =
some simple experiments which provided enlightening observations I have =
formed an opinion that Carbon dioxide, released as a free gas which =
collects along shear planes (caused by pug milling, wedging, kneading or =
other plastic clay forming processes) in flock structures, provides a =
trigger mechanism which initiates cracks under conditions of high drying =
stress.
It is not my intention to explain this on Clayart or to answer questions =
but comments would be appreciated.
Best regards,
Ivor Lewis. Redhill, South Australia.
In any population the degree of common sense varies inversely to the =
weight of popular opinion
Emma on sun 17 jun 01
David,
There should have been a sentence at the beginning of Ivor's post.
"Pots incorrectly or badly thrown". I use a body which is prone to S-cracks
and it is down to the thrower, I can say this because my wife uses the same
body and has never had any kind of crack in 15 years of use. We employed
throwers whose bottom lips nearly reached their waists when we told them we
were going to show them how to throw properly. Now we have given up being
employers. I don't care what technically happens after a pot is badly thrown
and I don't think any potter trying to make a living from pottery cares, I
want a pot thrown in a way which eliminates the possibility of cracking.
Regards,
Bob Hollis, who had his wife teach him to throw correctly.
----- Original Message -----
From: "David Hendley"
To:
Sent: 17 June 2001 02:31
Subject: Re: "S" Crack Initiation.
> Dear Ivor, I don't know if this is a question you don't wish to answer,
but
> I would be interested in knowing what your 'simple experiments'
> concerning the release of carbon dioxide were.
> I think that there are several factors at play that cause S-cracks, and
this
> may well be a contributing force.
>
> David Hendley
> Maydelle, Texas
> hendley@tyler.net
> http://www.farmpots.com
>
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