gshaffer on mon 24 dec 01
The only bloating problems I have had in the past was when I used a high
percentage of redart clay and goldart clay together in a stoneware
recepie, to get a really dark stoneware. This was back when goldart was
so high in sulfur...not sure about it's sulfur content currently as I do
not use it now. I have noticed recently an increase in sulfur or some
other gaseous matter in the Hawthorne Bonding Clay I switched to. I now
have my fireclay content down to only 5 % of my clay body and have cured
many ills from pinholes to glaze blistering to pop offs. Try mixing a
claybody and testing on your own to achieve the color you like and have
your own mixed by a company.
Gary Shaffer
Edouard Bastarache on mon 24 dec 01
Hello Gary,
very interesting and informative explanation from personal experience.
Later on #pottery,
Edouard Bastarache
Irreductible Quebecois
Indomitable Quebeker
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
http://sorel-tracy.qc.ca/~edouardb/
http://perso.wanadoo.fr/smart2000/index.htm
----- Original Message -----
From: gshaffer
To:
Sent: Monday, December 24, 2001 2:07 AM
Subject: Re: CLAYART Digest - bloating
> The only bloating problems I have had in the past was when I used a high
> percentage of redart clay and goldart clay together in a stoneware
> recepie, to get a really dark stoneware. This was back when goldart was
> so high in sulfur...not sure about it's sulfur content currently as I do
> not use it now. I have noticed recently an increase in sulfur or some
> other gaseous matter in the Hawthorne Bonding Clay I switched to. I now
> have my fireclay content down to only 5 % of my clay body and have cured
> many ills from pinholes to glaze blistering to pop offs. Try mixing a
> claybody and testing on your own to achieve the color you like and have
> your own mixed by a company.
>
> Gary Shaffer
>
>
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Ron Roy on sat 29 dec 01
Just to add to this - I monitor clay bodies for Tuckers - some of our
bodies are about 1/3 Hawthorn and we do not get problems from them.
What I am trying to point out is that - it is not necessary to eliminate
fire clay to get good working bodies if you understand what is necessary to
work with them.
1. Screen through 30 mesh
2. Bisque slow enough and in an OXIDIZING atmosphere to eliminate any
carbon and sulphur
3. Make sure the clay is not over vitrified.
The advantages of having a course grained fire clay.
1. Easier drying
2. Better throwing - gives some added structure to clay.
3. Gives iron spotting in reduction.
I personally prefer some fire clay in any stoneware body I use but if you
don't follow the "rules" or don't understand the issues at least - I can
see how it would be counter productive. I like the reaction between clay
and glaze and part of that comes from fire clay - especially in reduction.
RR
>The only bloating problems I have had in the past was when I used a high
>percentage of redart clay and goldart clay together in a stoneware
>recepie, to get a really dark stoneware. This was back when goldart was
>so high in sulfur...not sure about it's sulfur content currently as I do
>not use it now. I have noticed recently an increase in sulfur or some
>other gaseous matter in the Hawthorne Bonding Clay I switched to. I now
>have my fireclay content down to only 5 % of my clay body and have cured
>many ills from pinholes to glaze blistering to pop offs. Try mixing a
>claybody and testing on your own to achieve the color you like and have
>your own mixed by a company.
>
>Gary Shaffer
Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513
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