Peter Coates on fri 13 oct 06
Hello...
I went to an opening of Gay Smith's tonight. She is a soda fire
potter, and she fires a "soft brick" soda kiln. Tonight, I heard her
mention that her first kiln lasted 12 years. I am going to her
workshop tomorrow i'll find out more details and report back.
> http://www.gertrudegrahamsmith.com/
Peter in Oklahoma City
On Oct 13, 2006, at 9:20 AM, MudFire - Luba & Erik wrote:
> Hello all!
>
> I am building a soda kiln for our pottery center in Atlanta. We
> try in all things to be good earth guardians and energy
> efficient... and are willing to go forth with the "not very common"
> if it makes sense. The plan is to build a 35cu ft crossdraft,
> with a hardbrick floor, hardbrick around burner ports and bag wall
> and a double layer of IFB 2600 with ITC100 and ITC296 coating
> everywhere else. Welded frame. Cantenary arch with a 2+ rise. 250
> firings, as Vince Pitelka's kiln has done, is plenty of life for
> us as we will probably fire twice a month At that rate, it would
> last a decade!
>
> I would greatly value your opinion and input on several specific
> items.
>
> The first of which is this nagging issue of why there are so many
> qualified, experienced and intelligent people so diametrically
> opposed on the issue of IFB coated with ITC versus hardbrick.
> Since I've first read about this possibility in Nils Lou's book
> years ago, I've been excited by it. But have met with strong and
> intelligent counter-arguments from many studio potters whom we know
> who fire soda/salt in a hardbrick. I realize that IFB, no matter
> how well coated, will eventually degrade. But I've heard and read
> from many potters that this happens after hundreds of firings.
> Most hardbrick kilns have a similar lifespan (perhaps for other
> reasons, but nevertheless). Why such strong disagreement on this
> issue? Is it possible to incorrectly apply ITC and have it not
> work as it should? It is "religion"? Have there simply not been
> enough IFB soda kilns made for the word to spread?
>
> Second. I've heard that ITC or any other coating may begin to
> spall and fall into the wares after a number of firings. Should
> the arch therefore be made of hardbrick? If so, would that cause
> strange and unnatural pressures where he hotface of hardbrick and
> IFB come together at the top? Anything different I should think
> about there? Or just go with the IFB arch and keep scraping and
> reapplying the ITC.
>
> Third. I've talked to a number of people who accelerate the
> "seasoning" of their soda kilns by spraying a diluted mixture of
> shino glaze and water into the kiln on the first firing. This is
> done instead of feeding tons of soda in to create the "glaze" on
> the interior. For those of you who have done this, would ITC
> essentially do this same thing? Or would it make sense to do
> something on top of the ITC coating? Or does ITC simply repel
> anytning from sticking to the walls and that's its beauty?
>
> I know this is quite a bit of waffling on my part. I simply don't
> understand how there's not a grey area on this issue. People are
> strong defenders of both sides of this. I'd love to have this kiln
> be 400K BTUs instead of a million. But would also need it to last
> for at least four or five years.
>
> Any thoughts of discussion of this would be greatly appreciated!
> Thank you all!
> Luba
>
> MudFire Clayworks & Gallery
> Open Studio * Workshops * Exhibits
>
> 175 Laredo Dr, Decatur, GA 30030
> 404-377-8033
> www.mudfire.com
>
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Vince Pitelka on fri 13 oct 06
Luba at Mudfire wrote:
"I am building a soda kiln for our pottery center in Atlanta. We try in all
things to be good earth guardians and energy efficient... and are willing to
go forth with the "not very common" if it makes sense. The plan is to
build a 35cu ft crossdraft, with a hardbrick floor, hardbrick around burner
ports and bag wall and a double layer of IFB 2600 with ITC100 and ITC296
coating everywhere else. Welded frame. Cantenary arch with a 2+ rise. 250
firings, as Vince Pitelka's kiln has done, is plenty of life for us as we
will probably fire twice a month At that rate, it would last a decade!"
Luba -
I wish I could give you some encouragment on this, but in the end our
experiences with IFB soda kilns were not good. I cannot remember my exact
comments on Clayart regarding IFB soda kilns, but we have switched back to
all hardbrick on the inside of our soda kilns, and softbrick on the outside.
We just had too much trouble with IFB as a hotface in soda kilns. I never
kept exact track of the number of firings we got out of several successive
IFB soda kilns we built. It might have been as high as 250, but if so, it
was a real fight to get that many firings out of them. We had so much
trouble with deterioration of surface (even with ITC coating), and
separation of the inside crust, pieces falling on the wares. Also, as soon
as the soda begins to penetrate the bricks, they tend to contract, becoming
denser, and thus they absorb far more energy than new IFB, and thus I don't
think that the fuel savings are significant except when the kiln is brand
new. The degrading doesn't start after 100 firings. It starts immediately,
and just gets worse and worse over time. I think I may have painted an
overly-rosy picture of IFB soda kilns when we were using them. I got tired
of fussing with them. Our current hardbrick-hotface soda kiln has been
trouble-free. We still sprayed the bricks with ITC. As compared to the IFB
soda kilns, this one seems to fire in about the same amount of time on about
the same amount of gas pressure.
To my knowledge, there have not been any IFB soda kilns built that have
stood up to serious use over any significant period of time.
Good luck -
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
Vince Pitelka on fri 13 oct 06
Marcia Selsor wrote:
> You might try using an high alumina castable for the arch. If you
> used even just the inner layer and went to a less expensive castable
> farther away from the soda, this could be lighter weight than a hard
> brick arch. Just a thought.
Marcia -
You are a voice of reason and knowledge on this list, but I have to pipe in
here and say that our experience with high-alumina refractories in salt and
soda has been very unsatisfactory. Alumina does tend to resist deposition
of sodium vapors on the surface, but high alumina refractories do not resist
the absorption of sodium internally, and they tend to sponge and spall very
badly. About ten years ago we built a 60-cubic foot salt kiln out of AP
Green Kruzite high-alumina bricks, and it only lasted three years. It was
amazing and very disturbing how the interior surface started moving around
and separating. We had the same problem with high-alumina castable, so I am
staying away from high-alumina products in salt and soda kilns.
Several years ago, Hank Murrow posted a message to Clayart about a salt kiln
at U of O that was built out of high-silica firebrick. The idea was that
the silica would be attacked by the sodium and form a glaze on the inside,
essentially sealing the brick and preventing further penetration by sodium
vapors. I guess it worked out pretty well, but I'll be that kiln produced a
good share of drips on the wares.
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
MudFire - Luba & Erik on fri 13 oct 06
Hello all!
I am building a soda kiln for our pottery center in Atlanta. We try in =
all things to be good earth guardians and energy efficient... and are =
willing to go forth with the "not very common" if it makes sense. The =
plan is to build a 35cu ft crossdraft, with a hardbrick floor, =
hardbrick around burner ports and bag wall and a double layer of IFB =
2600 with ITC100 and ITC296 coating everywhere else. Welded frame. =
Cantenary arch with a 2+ rise. 250 firings, as Vince Pitelka's kiln has =
done, is plenty of life for us as we will probably fire twice a month At =
that rate, it would last a decade!
I would greatly value your opinion and input on several specific items. =
The first of which is this nagging issue of why there are so many =
qualified, experienced and intelligent people so diametrically opposed =
on the issue of IFB coated with ITC versus hardbrick. Since I've first =
read about this possibility in Nils Lou's book years ago, I've been =
excited by it. But have met with strong and intelligent =
counter-arguments from many studio potters whom we know who fire =
soda/salt in a hardbrick. I realize that IFB, no matter how well =
coated, will eventually degrade. But I've heard and read from many =
potters that this happens after hundreds of firings. Most hardbrick =
kilns have a similar lifespan (perhaps for other reasons, but =
nevertheless). Why such strong disagreement on this issue? Is it =
possible to incorrectly apply ITC and have it not work as it should? It =
is "religion"? Have there simply not been enough IFB soda kilns made for =
the word to spread?
Second. I've heard that ITC or any other coating may begin to spall and =
fall into the wares after a number of firings. Should the arch =
therefore be made of hardbrick? If so, would that cause strange and =
unnatural pressures where he hotface of hardbrick and IFB come together =
at the top? Anything different I should think about there? Or just go =
with the IFB arch and keep scraping and reapplying the ITC.
Third. I've talked to a number of people who accelerate the "seasoning" =
of their soda kilns by spraying a diluted mixture of shino glaze and =
water into the kiln on the first firing. This is done instead of =
feeding tons of soda in to create the "glaze" on the interior. For those =
of you who have done this, would ITC essentially do this same thing? Or =
would it make sense to do something on top of the ITC coating? Or does =
ITC simply repel anytning from sticking to the walls and that's its =
beauty? =20
I know this is quite a bit of waffling on my part. I simply don't =
understand how there's not a grey area on this issue. People are strong =
defenders of both sides of this. I'd love to have this kiln be 400K =
BTUs instead of a million. But would also need it to last for at least =
four or five years. =20
Any thoughts of discussion of this would be greatly appreciated!
Thank you all!
Luba
MudFire Clayworks & Gallery
Open Studio * Workshops * Exhibits
175 Laredo Dr, Decatur, GA 30030
404-377-8033
www.mudfire.com
Hank Murrow on fri 13 oct 06
On Oct 13, 2006, at 7:20 AM, MudFire - Luba & Erik wrote:
>
> I am building a soda kiln for our pottery center in Atlanta. We try
> in all things to be good earth guardians and energy efficient... and
> are willing to go forth with the "not very common" if it makes sense.
> The plan is to build a 35cu ft crossdraft, with a hardbrick floor,
> hardbrick around burner ports and bag wall and a double layer of IFB
> 2600 with ITC100 and ITC296 coating everywhere else. Welded frame.
> Cantenary arch with a 2+ rise. 250 firings, as Vince Pitelka's kiln
> has done, is plenty of life for us as we will probably fire twice a
> month At that rate, it would last a decade!
Dear Luba & Eric;
There is an alternative to the plans you have looked at. Could you cast
1" thick panels of hard castable with s.s. wire re-inforcement and back
those up with 6_8" of ceramic fiber? I imagine that with a castable
like Flo-cast 30S from Pryor Gigge and 2300F fiber behind the
castable..........that you could end up with a very efficient kiln that
would last many firings. We are trying that method but have not
completed the first one so cannot report how well it lasts, but tests
of the cast panels in local slat/soda firings suggest that it is a
reasonable plan. Another point in favor of such an approach is that the
panels are cast from molds, giving one the advantage of being able to
cast new or backup panels when repair is finally needed. And the molds
can be finely finished, giving the hot face a glass-smooth surface that
reduces the surface for glaze to form on.
Cheers, Hank
www.murrow.biz/hank
Marcia Selsor on fri 13 oct 06
You might try using an high alumina castable for the arch. If you
used even just the inner layer and went to a less expensive castable
farther away from the soda, this could be lighter weight than a hard
brick arch. Just a thought.
Marcia Selsor
http://marciaselsor.com
On Oct 13, 2006, at 9:20 AM, MudFire - Luba & Erik wrote:
> Hello all!
>
> I am building a soda kiln for our pottery center in Atlanta. We
> try in all things to be good earth guardians and energy
> efficient... and are willing to go forth with the "not very common"
> if it makes sense. The plan is to build a 35cu ft crossdraft,
> with a hardbrick floor, hardbrick around burner ports and bag wall
> and a double layer of IFB 2600 with ITC100 and ITC296 coating
> everywhere else. Welded frame. Cantenary arch with a 2+ rise. 250
> firings, as Vince Pitelka's kiln has done, is plenty of life for
> us as we will probably fire twice a month At that rate, it would
> last a decade!
>
> I would greatly value your opinion and input on several specific
> items.
>
> The first of which is this nagging issue of why there are so many
> qualified, experienced and intelligent people so diametrically
> opposed on the issue of IFB coated with ITC versus hardbrick.
> Since I've first read about this possibility in Nils Lou's book
> years ago, I've been excited by it. But have met with strong and
> intelligent counter-arguments from many studio potters whom we know
> who fire soda/salt in a hardbrick. I realize that IFB, no matter
> how well coated, will eventually degrade. But I've heard and read
> from many potters that this happens after hundreds of firings.
> Most hardbrick kilns have a similar lifespan (perhaps for other
> reasons, but nevertheless). Why such strong disagreement on this
> issue? Is it possible to incorrectly apply ITC and have it not
> work as it should? It is "religion"? Have there simply not been
> enough IFB soda kilns made for the word to spread?
>
> Second. I've heard that ITC or any other coating may begin to
> spall and fall into the wares after a number of firings. Should
> the arch therefore be made of hardbrick? If so, would that cause
> strange and unnatural pressures where he hotface of hardbrick and
> IFB come together at the top? Anything different I should think
> about there? Or just go with the IFB arch and keep scraping and
> reapplying the ITC.
>
> Third. I've talked to a number of people who accelerate the
> "seasoning" of their soda kilns by spraying a diluted mixture of
> shino glaze and water into the kiln on the first firing. This is
> done instead of feeding tons of soda in to create the "glaze" on
> the interior. For those of you who have done this, would ITC
> essentially do this same thing? Or would it make sense to do
> something on top of the ITC coating? Or does ITC simply repel
> anytning from sticking to the walls and that's its beauty?
>
> I know this is quite a bit of waffling on my part. I simply don't
> understand how there's not a grey area on this issue. People are
> strong defenders of both sides of this. I'd love to have this kiln
> be 400K BTUs instead of a million. But would also need it to last
> for at least four or five years.
>
> Any thoughts of discussion of this would be greatly appreciated!
> Thank you all!
> Luba
>
> MudFire Clayworks & Gallery
> Open Studio * Workshops * Exhibits
>
> 175 Laredo Dr, Decatur, GA 30030
> 404-377-8033
> www.mudfire.com
Marcia Selsor
http://marciaselsor.com
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