Marcia Selsor on wed 25 jul 07
I don't agree with Paul because the the whole premise of what is
happening in a salt/soda kiln is this...the soda attacks the silica
in the clay. This creates the etching of glaze on the surface of the
clay.
Clay shelves are equally vulnerable to the silica etching. Silicon
Carbide shelves are not.
The clay shelves will not hold up in a soda firing IMHO. I agree
they'd get the syrup build up.
Marcia Selsor
http://marciaselsor.com
On Jul 25, 2007, at 6:26 PM, Paul Herman wrote:
> Hi Bonita,
>
> I think they can be used in salt and soda alright, as long as they
> will hold up to the temps. They won't be as easy to clean as silicon
> carbide. SiC shelves get "foamy bubbles" that are easy to scrape off.
> Clay shelves would act more like fire brick, getting a thick
> "chocolate syrup" glaze on them.
>
> best from sweltering Doyle,
>
> Paul Herman
>
> Great Basin Pottery
> Doyle, California US
> http://greatbasinpottery.com
>
>
> On Jul 25, 2007, at 2:39 PM, Bonita Cohn wrote:
>
>> Hi -- I have a potential buyer for my shelves.
>> We rebuilt our kiln and now have advancers!
>> That the interested party is building a salt/soda
>> kiln.
>>
>> Some of these shelves are the yellow-clay type
>> shelves.
>> My question is, Can the clay shelves be used in the
>> salt/soda?
>>
>> I recall them in other salt/wood firings in which I
>> have participated.
>> I know they have a lower limit than the silicon
>> carbide.
>>
>> Thanks in advance from Foggy San Francisco.
>> (I needed extra blankets last night!)
>>
>> Bonita
>>
>> Bonita Cohn
>> http://www.bonitacohn.com
Bonita Cohn on wed 25 jul 07
Hi -- I have a potential buyer for my shelves.
We rebuilt our kiln and now have advancers!
That the interested party is building a salt/soda
kiln.
Some of these shelves are the yellow-clay type
shelves.
My question is, Can the clay shelves be used in the
salt/soda?
I recall them in other salt/wood firings in which I
have participated.
I know they have a lower limit than the silicon
carbide.
Thanks in advance from Foggy San Francisco.
(I needed extra blankets last night!)
Bonita
Bonita Cohn
http://www.bonitacohn.com
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Paul Herman on wed 25 jul 07
Hi Bonita,
I think they can be used in salt and soda alright, as long as they
will hold up to the temps. They won't be as easy to clean as silicon
carbide. SiC shelves get "foamy bubbles" that are easy to scrape off.
Clay shelves would act more like fire brick, getting a thick
"chocolate syrup" glaze on them.
best from sweltering Doyle,
Paul Herman
Great Basin Pottery
Doyle, California US
http://greatbasinpottery.com
On Jul 25, 2007, at 2:39 PM, Bonita Cohn wrote:
> Hi -- I have a potential buyer for my shelves.
> We rebuilt our kiln and now have advancers!
> That the interested party is building a salt/soda
> kiln.
>
> Some of these shelves are the yellow-clay type
> shelves.
> My question is, Can the clay shelves be used in the
> salt/soda?
>
> I recall them in other salt/wood firings in which I
> have participated.
> I know they have a lower limit than the silicon
> carbide.
>
> Thanks in advance from Foggy San Francisco.
> (I needed extra blankets last night!)
>
> Bonita
>
> Bonita Cohn
> http://www.bonitacohn.com
>
>
>
> ______________________________________________________________________
> ______________
> Get the Yahoo! toolbar and be alerted to new email wherever you're
> surfing.
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>
> ______________________________________________________________________
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>
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>
>
Charles Hightower on thu 26 jul 07
I'm sure if Nils is out there, he can confirm this. I
have only heard that a coat of ITC 100 will help
reject the salt buildup.
--- Paul Herman wrote:
> Hi Bonita,
>
> I think they can be used in salt and soda alright,
> as long as they
> will hold up to the temps. They won't be as easy to
> clean as silicon
> carbide. SiC shelves get "foamy bubbles" that are
> easy to scrape off.
> Clay shelves would act more like fire brick, getting
> a thick
> "chocolate syrup" glaze on them.
>
> best from sweltering Doyle,
>
> Paul Herman
>
> Great Basin Pottery
> Doyle, California US
> http://greatbasinpottery.com
>
>
> On Jul 25, 2007, at 2:39 PM, Bonita Cohn wrote:
>
> > Hi -- I have a potential buyer for my shelves.
> > We rebuilt our kiln and now have advancers!
> > That the interested party is building a salt/soda
> > kiln.
> >
> > Some of these shelves are the yellow-clay type
> > shelves.
> > My question is, Can the clay shelves be used in
> the
> > salt/soda?
> >
> > I recall them in other salt/wood firings in which
> I
> > have participated.
> > I know they have a lower limit than the silicon
> > carbide.
> >
> > Thanks in advance from Foggy San Francisco.
> > (I needed extra blankets last night!)
> >
> > Bonita
> >
> > Bonita Cohn
> > http://www.bonitacohn.com
> >
> >
> >
> >
>
______________________________________________________________________
> > ______________
> > Get the Yahoo! toolbar and be alerted to new email
> wherever you're
> > surfing.
> >
>
http://new.toolbar.yahoo.com/toolbar/features/mail/index.php
> >
> >
>
______________________________________________________________________
> > ________
> > Send postings to clayart@lsv.ceramics.org
> >
> > You may look at the archives for the list or
> change your subscription
> > settings from http://www.ceramics.org/clayart/
> >
> > Moderator of the list is Mel Jacobson who may be
> reached at
> > melpots@pclink.com.
> >
> >
>
>
______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
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>
Vince Pitelka on mon 30 jul 07
Marcia Selsor wrote:
>I don't agree with Paul because the the whole premise of what is
> happening in a salt/soda kiln is this...the soda attacks the silica
> in the clay. This creates the etching of glaze on the surface of the
> clay.
> Clay shelves are equally vulnerable to the silica etching. Silicon
> Carbide shelves are not.
> The clay shelves will not hold up in a soda firing IMHO. I agree
> they'd get the syrup build up.
I'd have to agree with Marcia here. Paul has a salting chamber on his bi=
g
anagama, and perhaps with the infrequency of firing, his clay shelves are
holding up well. At the Craft Center we fire our salt and soda kilns a
lot, and clay shelves do not hold up at all. Part of the problem is that
they are porous, and remain so on the wash-coated upper surface, so the
sodium vapors penetrate the clay and build up internally, eventually
fluxing the clay and causing potentially catastrophic (in relative terms)
failure.
- Vince
--=20
Vince Pitelka
Appalachian Center for Craft
Tennessee Technological University
vpitelka@dtccom.net
http://iweb.tntech.edu/wpitelka/
Paul Herman on mon 30 jul 07
Vince,
Actually, we are using only silicon carbide in the salt chamber.
However, my friend Joe has been using some clay shelves in his wood/
salt kiln, and as far as I know they seem to be doing alright. He
fires four or five times a year. I'll see if he knows how many
firings they've been through.
Paul Herman
Great Basin Pottery
Doyle, California US
http://greatbasinpottery.com
On Jul 30, 2007, at 11:33 AM, Vince Pitelka wrote:
> Marcia Selsor wrote:
>
>> I don't agree with Paul because the the whole premise of what is
>> happening in a salt/soda kiln is this...the soda attacks the silica
>> in the clay. This creates the etching of glaze on the surface of the
>> clay.
>> Clay shelves are equally vulnerable to the silica etching. Silicon
>> Carbide shelves are not.
>> The clay shelves will not hold up in a soda firing IMHO. I agree
>> they'd get the syrup build up.
>>
>
> I'd have to agree with Marcia here. Paul has a salting chamber on
> his big
> anagama, and perhaps with the infrequency of firing, his clay
> shelves are
> holding up well. At the Craft Center we fire our salt and soda
> kilns a
> lot, and clay shelves do not hold up at all. Part of the problem
> is that
> they are porous, and remain so on the wash-coated upper surface, so
> the
> sodium vapors penetrate the clay and build up internally, eventually
> fluxing the clay and causing potentially catastrophic (in relative
> terms)
> failure.
> - Vince
>
Ted Neal on tue 31 jul 07
Vince/ Paul
On the whole I agree that clay shelves and salt are a bad combination.
In the end they tear themselves apart. Delaminate for lack of a better
description.
On the other hand we had very thick clay shelves at Utah State University where I was
the tech. We got the Kohler used shelves. Massive 100 pounders. 2' x 3' x 1.5" They did quite
well in the wood kiln. There are many of the same volitiles but certainly not to the same level
as a salt firing. The nice thing was no dripping from the bottom of the shelves and most of the
ash wiped off...high alumina shelves perhaps
There is one thing that no one has mentioned with 'clay' shelves and that is the alumina content
and manufacturing process used to produce the shelf. That may make some difference but in the
end I'm sure it would not make enough of a difference for salt kilns...
Best
Ted
Ted Neal
Ball State University
On Mon, 30 Jul 2007 15:46:08 -0700, Paul Herman wrote:
>Vince,
>
>Actually, we are using only silicon carbide in the salt chamber.
>However, my friend Joe has been using some clay shelves in his wood/
>salt kiln, and as far as I know they seem to be doing alright. He
>fires four or five times a year. I'll see if he knows how many
>firings they've been through.
>
>Paul Herman
>
>Great Basin Pottery
>Doyle, California US
>http://greatbasinpottery.com
>
>
>On Jul 30, 2007, at 11:33 AM, Vince Pitelka wrote:
>
>> Marcia Selsor wrote:
>>
>>> I don't agree with Paul because the the whole premise of what is
>>> happening in a salt/soda kiln is this...the soda attacks the silica
>>> in the clay. This creates the etching of glaze on the surface of the
>>> clay.
>>> Clay shelves are equally vulnerable to the silica etching. Silicon
>>> Carbide shelves are not.
>>> The clay shelves will not hold up in a soda firing IMHO. I agree
>>> they'd get the syrup build up.
>>>
>>
>> I'd have to agree with Marcia here. Paul has a salting chamber on
>> his big
>> anagama, and perhaps with the infrequency of firing, his clay
>> shelves are
>> holding up well. At the Craft Center we fire our salt and soda
>> kilns a
>> lot, and clay shelves do not hold up at all. Part of the problem
>> is that
>> they are porous, and remain so on the wash-coated upper surface, so
>> the
>> sodium vapors penetrate the clay and build up internally, eventually
>> fluxing the clay and causing potentially catastrophic (in relative
>> terms)
>> failure.
>> - Vince
>>
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
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