Eduardo Lazo on fri 25 may 07
Both Jackie and Meg have posed questions that I often get in my workshops:
"Is it possible to pit fire paper clay porcelain without a bisque or
any other paperclay for that matter? - Jackie Miller"
"I do not have an answer but am also wondering about Raku firing
''green? - Meg"
Yes, it is possible. The caveat lies in the nature of your clay body's
composition. We see the Southwest American Indians and the Mexican Potters of Mata
Ortiz firing indigenous clay greenware all the time with minimal breakage.
They use variations of pit and barrel firing methods.
I have found that most commercial American clay bodies do not withstand the
rapid heating so characteristic of pit and raku firings. That is not to say
that it cannot be done. Bodies with grog or sand have a better chance of making
it through the process without breaking. Rounded shapes do better than flat
pieces. When constructing your pit, I suggest the trench style. Place your
thoroughly dry greenware (heated in an oven, kiln or barbecue and held at below
the boiling point of water for at least an hour) at the far end of the
trench, away from the prevailing wind. That way, the greenware has a chance to
continue to preheat before the flames reach it.
With raku (given the "proper" clay body) I would fire very, very, very slowly
up to 1100 degrees Fahrenheit. Drying as described above is recommended here
too.
But then, why take a chance. Just bisque to Orton cone 018 and don't worry
about it.
Eduardo Lazo
Belmont, California
************************************** See what's free at http://www.aol.com.
Eduardo Lazo on fri 25 may 07
Both Jackie and Meg have posed questions that I often get in my workshops:
"Is it possible to pit fire paper clay porcelain without a bisque or
any other paperclay for that matter? - Jackie Miller"
"I do not have an answer but am also wondering about Raku firing
''green? - Meg"
Yes, it is possible. The caveat lies in the nature of your clay body's
composition. We see the Southwest American Indians and the Mexican Potters of Mata
Ortiz firing indigenous clay greenware all the time with minimal breakage.
They use variations of pit and barrel firing methods.
I have found that most commercial American clay bodies do not withstand the
rapid heating so characteristic of pit and raku firings. That is not to say
that it cannot be done. Bodies with grog or sand have a better chance of making
it through the process without breaking. Rounded shapes do better than flat
pieces. When constructing your pit, I suggest the trench style. Place your
thoroughly dry greenware (heated in an oven, kiln or barbecue and held at below
the boiling point of water for at least an hour) at the far end of the
trench, away from the prevailing wind. That way, the greenware has a chance to
continue to preheat before the flames reach it.
With raku (given the "proper" clay body) I would fire very, very, very slowly
up to 1100 degrees Fahrenheit. Drying as described above is recommended here
too.
But then, why take a chance. Just bisque to Orton cone 018 and don't worry
about it.
Eduardo Lazo
Belmont, California
************************************** See what's free at http://www.aol.com.
Jacqueline Miller on fri 25 may 07
Eduardo: Thank you very much for your comments and for your wonderful
articles about pit firing that I have found on the web. I agree that
it makes much more sense to bisque. My question came up when I found
myself "kilnless in Pepper Pike." I think I may now have somewhere to
do a bisque, but it might be interesting to fire a piece of greenware
(away from everything else) just to experiment. This is the first pit
fire for a little group of us. It may be the blind leading the blind
but should be fun. I will report our results.
Jackie
On 5/25/07, Eduardo Lazo wrote:
> Both Jackie and Meg have posed questions that I often get in my workshops:
> "Is it possible to pit fire paper clay porcelain without a bisque or
> any other paperclay for that matter? - Jackie Miller"
> "I do not have an answer but am also wondering about Raku firing
> ''green? - Meg"
> Yes, it is possible. The caveat lies in the nature of your clay body's
> composition. We see the Southwest American Indians and the Mexican Potters of Mata
> Ortiz firing indigenous clay greenware all the time with minimal breakage.
> They use variations of pit and barrel firing methods.
> I have found that most commercial American clay bodies do not withstand the
> rapid heating so characteristic of pit and raku firings. That is not to say
> that it cannot be done. Bodies with grog or sand have a better chance of making
> it through the process without breaking. Rounded shapes do better than flat
> pieces. When constructing your pit, I suggest the trench style. Place your
> thoroughly dry greenware (heated in an oven, kiln or barbecue and held at below
> the boiling point of water for at least an hour) at the far end of the
> trench, away from the prevailing wind. That way, the greenware has a chance to
> continue to preheat before the flames reach it.
> With raku (given the "proper" clay body) I would fire very, very, very slowly
> up to 1100 degrees Fahrenheit. Drying as described above is recommended here
> too.
> But then, why take a chance. Just bisque to Orton cone 018 and don't worry
> about it.
> Eduardo Lazo
> Belmont, California
>
>
>
>
>
> ************************************** See what's free at http://www.aol.com.
>
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--
Jackie Miller
JackieAMiller@gmail.com
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