Merrie Boerner on sat 5 may 01
Hi Friends,
Matt MacIntire e-mailed me a question that I can't answer......any
suggestions ?
Here is the last part of two of his post.........
"The 40 cu ft. single chamber wood kiln I have been working at fires in
about
15 hours to cone 10 using close to 2 cords of wood. We don't get very mu=
ch
ash buildup, regardless of the type of clay. We wad everything, but it
seems unnecessary to me, since so little ash builds up. I wonder if our
firing time is just too short for much buildup...?"
"I wish we did get more ash. Some fly ash seems to stick later in the
firing, but doesn't have long enough to melt out. Leaves a gritty surfac=
e.
I like the way things look, but folks who are used to gas firing are
disappointed by how the late fly ash roughens the surface of open pieces.=
I
just fire my bowls upside down, so I don't mind. But I would like more a=
sh
buildup. "
"It seems easy to get to cone 7 or so with our little wood kiln, but it i=
s
very tricky to manage the kiln to advance that last bit. It takes severa=
l
hours to get the last couple cones down.
I wonder if something about the kiln design is limiting us. The firebox
grate area seems quite large in comparison to the kiln space. I'd estima=
te
the grate size as about, say, 16" X 42". But the airspace seems tight to
me. The opening for air is only about 150-200 square inches (1 - 1.4 sq
ft.) this is about equal to the cross section of the chimney.
One thing I have always found curious about this kiln is that there
typically is a lot of unburnt fuel in the chimney. I estimate the chimne=
y
is about 14 feet tall. Often during firing, flames shoot out of the chim=
ney
several feet into the air. If this were a gas kiln with blowers, I'd
increase the air to shorten the flame. This is not my kiln, and I haven'=
t
yet convinced them to try a more oxidizing flame as the firing progresses=
=2E
As it fires now, the kiln is in light reduction most of the firing. As t=
he
wood burns off and it is time to stoke, then it approaches oxidizing
conditions."
Thanks Yall,
Merrie
Tony Ferguson on sun 6 may 01
--- Matt MacIntire wrote:
> Since my messages can ramble a bit too much
> sometimes, without coming to the
> point, let me formulate the questions I posed to
> Merrie a bit more
> succinctly.
>
> If you have a woodburing kiln...
>
> 1> How does the size of the firebox compare to the
> size of the ware chamber?
my firebox is almost half the size of the ware chamber
> 2> How does the size of the primary air intake
> relate to the size of the
> firebox? and chimney?
primary air relationship has to do with the size of
your chimney/amount of draw--this will affect your
burn, heat rise or stagnation. You want enough draw
yet if the stack draws to much (some people have what
are called passive dampers that let cool air in the
stack to slow it down)if will pull the heat out. I
damper my stack to control flow. There is a NASA like
term for this type of heat flow but it escapes me.
Some people put a wall in the back of their kilns (I'm
thinking Anagama) while others leave it open and
damper off the stack or bottom back of the kiln where
the body of the kiln meets the stack. There are many
rules, laws, blah blah blah--my father who is an
engineer said I need at least 3 feet of chimney above
the arch. With a 1 foot chimney for my first firing
with my Anagama(the name stubby comes to mind) I fired
to cone 8. So rules don't always apply. I also
didn't know what the hell I was doing--which can be a
good thing or a bad thing. Just depends on what you
want. The big girls and boys of ash, patina, and
flashing seem to have Anagamas. More functional folk
seem to have sprung arch or gas like wood kilns: Fred
Olsen fast fire, MN flat top, sprung arch, etc. The
kiln you will build should be able to give you the
aesthetic you want. If you want ash (unless you want
to fire chop sticks AND cut wood up for weeks)you
aren't going to get the killer ash if you build a gas
type wood kiln. You could shake and bake, however.
If you want the ash, build an Anagama and nuke the
hell out of your work. If you want function, a Fred
Olsen fast fire kiln can work and is easy to build.
Remember that wood kilns came first and gas kilns were
modeled after them. You have to reverse your thinking
and throw a lot of what you think you know out and
relearn as you fire with wood. Find a kiln design
type you like, and build it. You can't screw it
up--well, maybe the first 3-5 firings--it depends on
how much risk you are willing to take or if you want
to play it safe. Both are fine.
> I've read that a mouse hole at the bottom and side
> of the ash pit helps the
> coals to burn off better. Can anyone confirm this
> to be true? Seems like
> the mouse hole would get choked over with coals
> right away. We end up with
> a pit filled with hot coals and no air intake below
> the top of the coals. I
> guess it is no wonder that the coals accumulate.
>
You need more air to burn those coals down. Ah the
joys of putting holes in your kiln where they didn't
exist before. Find someone who has done this, well.
I haven't.
> One more question... in a firebox that doesn't have
> a grate, do the coals
> build up to the point where the fire is choked by
> all the coals?
I have air intake above the floor of my fire box. IF
you over stoke and not enough air, coal accumulation
will happen and may block needed air. If you stoke
too much, you will over reduce and choke. I once used
a pyrometer at the request of some workshopees--it
helped them see the relationship between stoking,
oxidation and reduction. I do not have problems with
coals choking. Check out my kiln
http://acad.uwsuper.edu/www/aferguso/fergyart.htm
you will seem what I mean.
Good luck with modifying your kiln or building a new
one.
Tony Duluth, MN
=====
--Tony Ferguson, fergyart@yahoo.com315 N. Lake Ave. Apt 401Duluth, MN 55806(218) 727-6339Looking to see, buy or barter artwork go to:http://acad.uwsuper.edu/www/aferguso/fergyart.htm
Matt MacIntire on sun 6 may 01
Since my messages can ramble a bit too much sometimes, without coming to the
point, let me formulate the questions I posed to Merrie a bit more
succinctly.
If you have a woodburing kiln...
1> How does the size of the firebox compare to the size of the ware chamber?
2> How does the size of the primary air intake relate to the size of the
firebox? and chimney?
Merrie's kiln sounds like it can easily reach cone 13. Based on various
descriptions of her kiln, it seems to have quite a large firebox. Merrie's
prolonged firing cycle seems to have more to do with evening out the heat,
rather than simply getting to temperature.
Our kiln fires fairly evenly, since it is downdraft and rather small at 40
cubic feet. However, I don't think we could easily fire much past cone
eleven. It seems pretty difficult to maintain temperatures over 2300
degrees Fahrenheit. 2500 is inconceivable for me at this point.
Our firebox is probably half the size of the floor space of the kiln. We
can shove a lot of wood in there if we need to. I'm guessing we might be
better off with a bit more air. This kiln uses stainless steel grates and
the burning wood is held above the air intakes. But the ash pit (16" deep
under the whole grate) fills with coals and can choke off the air if we
don't rake out the coals periodically. If we don't rake out the coals and
keep the air intake fairly open the kiln stalls.
I've read that a mouse hole at the bottom and side of the ash pit helps the
coals to burn off better. Can anyone confirm this to be true? Seems like
the mouse hole would get choked over with coals right away. We end up with
a pit filled with hot coals and no air intake below the top of the coals. I
guess it is no wonder that the coals accumulate.
One more question... in a firebox that doesn't have a grate, do the coals
build up to the point where the fire is choked by all the coals? Maybe in
that style of firebox there is enough air that hot coals don't build up so
much.
Thanks in advance for your thoughts on the matter. And a special thanks to
Merrie for keeping the talk about wood firing so lively.
Matt
Tony Ferguson on sun 6 may 01
--- Merrie Boerner wrote:
> Hi Friends,
> Matt MacIntire e-mailed me a question that I
> can't answer......
I wonder if our
> firing time is just too short for much buildup...?"
> "I wish we did get more ash. Some fly ash seems to
> stick later in the
> firing, but doesn't have long enough to melt out.
> Leaves a gritty surface
--------------------------------------------------
how much feldspar is in your clay body?
Sounds like you need more feldspar in the body.
Is it a soft brick kiln?
Feldspar should help melt your ash--it could be your
glazes too.
Try a longer firing (will help quite a bit) to get
some good pot radiation--where the pots radiate heat
to each other. That may help to even out the heat and
melt some ash as well as my feldspar recommendation.
Tony Duluth, MN
=====
--Tony Ferguson, fergyart@yahoo.com315 N. Lake Ave. Apt 401Duluth, MN 55806(218) 727-6339Looking to see, buy or barter artwork go to:http://acad.uwsuper.edu/www/aferguso/fergyart.htm
don Ablett on sun 6 may 01
Hi Merrie, In the quiet wood kilns I've fired, when I want more ash deposit, I've
done a couple of things.Two things I would suggest....
1. Try throwing in things like evergreen boughs that burn up quickly and seem to
deposit good stuff
2, If all else fails, I sometimes sprinkle ash from a kitchen seive right on to my
pots in the kiln, to help them on their way. I think about how the ash would
naturally fall on the shoulders etc. of the pots and the direction it would move
in to get a natural look. Hope this helps.
Carol-Ann
Merrie Boerner wrote:
> Hi Friends,
> Matt MacIntire e-mailed me a question that I can't answer......any
> suggestions ?
> Here is the last part of two of his post.........
> "The 40 cu ft. single chamber wood kiln I have been working at fires in
> about
> 15 hours to cone 10 using close to 2 cords of wood. We don't get very much
> ash buildup, regardless of the type of clay. We wad everything, but it
> seems unnecessary to me, since so little ash builds up. I wonder if our
> firing time is just too short for much buildup...?"
> "I wish we did get more ash. Some fly ash seems to stick later in the
> firing, but doesn't have long enough to melt out. Leaves a gritty surface.
> I like the way things look, but folks who are used to gas firing are
> disappointed by how the late fly ash roughens the surface of open pieces. I
> just fire my bowls upside down, so I don't mind. But I would like more ash
> buildup. "
> "It seems easy to get to cone 7 or so with our little wood kiln, but it is
> very tricky to manage the kiln to advance that last bit. It takes several
> hours to get the last couple cones down.
> I wonder if something about the kiln design is limiting us. The firebox
> grate area seems quite large in comparison to the kiln space. I'd estimate
> the grate size as about, say, 16" X 42". But the airspace seems tight to
> me. The opening for air is only about 150-200 square inches (1 - 1.4 sq
> ft.) this is about equal to the cross section of the chimney.
> One thing I have always found curious about this kiln is that there
> typically is a lot of unburnt fuel in the chimney. I estimate the chimney
> is about 14 feet tall. Often during firing, flames shoot out of the chimney
> several feet into the air. If this were a gas kiln with blowers, I'd
> increase the air to shorten the flame. This is not my kiln, and I haven't
> yet convinced them to try a more oxidizing flame as the firing progresses.
> As it fires now, the kiln is in light reduction most of the firing. As the
> wood burns off and it is time to stoke, then it approaches oxidizing
> conditions."
> Thanks Yall,
> Merrie
>
> ______________________________________________________________________________
> 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.
Matt MacIntire on tue 8 may 01
Tony,
Thank you for all your informative comments. You make some excellent poi=
nts
that are well taken. I laughed at the "shake and bake" comment -- that i=
s
how it feels when I put ash on a pot. Like planning to be spontaneous...
This kiln works quite well, we just need to master a few details to feel
like we have a bit more control during the late stages of the firing. I
appreciate your help, and will try some adjustments based on your
suggestions.
You mentioned passive dampers and that seemed like a very important point=
=2E
Our kiln has a passive damper, but until you called it that, I didn't
appreciate its full purpose. Answers always lead me to more questions, =
so
please permit one more...
Question: Can anyone describe to me the best way to use a passive damper=
to
regulate draft?
Changing the size of the air intake, using the regular damper, and openin=
g a
passive damper in the chimney can all be used to regulate the draft in a
kiln. My suspicion is that as the temperature in the chimney increases t=
he
draft may get too powerful. At that point we could open the passive damp=
er
enough to reduces excessive draft, instead of dampering back and causing =
too
much reduction. So far we haven't been using the passive damper at all,
except to stop the draft at the end of the firing.
My guess is that late in the firing this could be a very useful adjustmen=
t.
This is a fast-fire style kiln. Our chimney is pretty tall. Ruth Ballou
wisely suggested to me, in a private message, that perhaps we have too mu=
ch
draft. I imagine that excessive draft could pull the heat out of the kil=
n
too fast. Too lively a draft would also diminish the ash deposits too.
This may be an important new way for us to manage firings in our kiln eve=
n
more effectively.
I appreciate the help of this group, whose collective wisdom and experien=
ce
far exceeds my own. My thanks to all who have responded.
Matt
Tony Ferguson on tue 8 may 01
Matt,
How long do you hold your kiln at or above cone 10?
Holding it a while may help you even the heat out.
Your passive damper will slow it down a bit--play with
that next firing.
Tony Duluth,MN
--- Matt MacIntire wrote:
> Tony,
>
> Thank you for all your informative comments. You
> make some excellent points
> that are well taken. I laughed at the "shake and
> bake" comment -- that is
> how it feels when I put ash on a pot. Like planning
> to be spontaneous...
>
>
> This kiln works quite well, we just need to master a
> few details to feel
> like we have a bit more control during the late
> stages of the firing. I
> appreciate your help, and will try some adjustments
> based on your
> suggestions.
>
> You mentioned passive dampers and that seemed like a
> very important point.
> Our kiln has a passive damper, but until you called
> it that, I didn't
> appreciate its full purpose. Answers always lead
> me to more questions, so
> please permit one more...
>
> Question: Can anyone describe to me the best way to
> use a passive damper to
> regulate draft?
>
> Changing the size of the air intake, using the
> regular damper, and opening a
> passive damper in the chimney can all be used to
> regulate the draft in a
> kiln. My suspicion is that as the temperature in
> the chimney increases the
> draft may get too powerful. At that point we could
> open the passive damper
> enough to reduces excessive draft, instead of
> dampering back and causing too
> much reduction. So far we haven't been using the
> passive damper at all,
> except to stop the draft at the end of the firing.
>
> My guess is that late in the firing this could be a
> very useful adjustment.
> This is a fast-fire style kiln. Our chimney is
> pretty tall. Ruth Ballou
> wisely suggested to me, in a private message, that
> perhaps we have too much
> draft. I imagine that excessive draft could pull
> the heat out of the kiln
> too fast. Too lively a draft would also diminish
> the ash deposits too.
> This may be an important new way for us to manage
> firings in our kiln even
> more effectively.
>
> I appreciate the help of this group, whose
> collective wisdom and experience
> far exceeds my own. My thanks to all who have
> responded.
>
>
> Matt
>
>
_________________________________________________________________________=
_____
> 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.
=3D=3D=3D=3D=3D
--Tony Ferguson, fergyart@yahoo.com315 N. Lake Ave. Apt 401Duluth, MN 55=
806(218) 727-6339Looking to see, buy or barter artwork go to:http://acad.=
uwsuper.edu/www/aferguso/fergyart.htm
Ruth Ballou on wed 9 may 01
Matt,
Using the passive damper is equivalent to decreasing the height of the
chimney. The introduction of air at that point also helps burn up the flue
gases.
I've found that it's important in firing a wood kiln to set up things right
from the start. It's very difficult to change patterns that have been set
early in the firing. With a gas kiln, you can make changes and they have an
effect pretty quickly. If you decide you want to cut the air back, it's
easy to also cut the gas back. With a wood kiln, because you're burning a
solid fuel, any change in the air must take into account the effect on the
coals. A lot of air requires that you stoke a lot of wood. That wood takes
time to burn, building the coal bed. As the temperature climbs the draft
will increase, requiring even more wood per stoke, adding to the coal bed.
Trying to get out of this by cutting the air means the coal bed will burn
slower. The next thing you know, the air is on it's way to being blocked
and the stokes aren't burning well either. As the kiln gets hotter and
hotter, making changes can be like trying to divert a runaway freight
train. It's much better to set the pattern from the beginning, controlling
the air so that you stoke as little wood as possible to get a temperature
rise. Increase the amount of wood in the stoke only when it is clear that
the temperature rise has leveled off. Stokes start burning real fast at
this point. It may not be necessary to increase the air because the chimney
will pull harder anyway as the temperature rises. Increase the air only
when it is obvious that the kiln needs it: the stokes have gotten
progressively larger, there's a heavy and long reduction phase with slow
temperature rise. At this point, I prefer to open the damper some, rather
than increasing the primary air. Since you have a passive damper, you can
start bricking it up. If you're going to use the passives, start with them
in during the preheat phase, when you're establishing draft and want to
hold the heat in, then out by the time you're stoking wood on the grates.
The primary air that was open for preheat should be much less by the time
you're on the grates. Increase the air on the front only when you've done
as much as you can with the chimney. Tiny changes can make a big
difference, so cut up soft brick into slivers. Dont' be surprised if you
end up with just 2 or 3 bricks out on the front. This is just one scenario.
Other settings will work as well, so long as the adjustments remain in
balance.
One thing I've noticed with group firings that can have a detrimental
effect on the outcome is the very human desire to keep checking the cones
or the stoke holes. Open these up as little as possible. Cold air is the
enemy. You should have a door design for the stoke hole that allows the
smallest crack to see the progress. Try to read the cones without fully
removing the brick.
Everyone has suggested extending the firing to get the ash to melt. I've
found that stretching it out to 4 or 5 hours between ^ 8 and ^10 makes a
difference.
That's my take on the big picture. I'm sure you've already discovered to
expect the unexpected in woodfiring .
Ruth Ballou
Matt MacIntire on thu 10 may 01
Ruth wrote:
>> I've found that it's important in firing a wood kiln to
>> set up things right from the start. It's very difficult
>> to change patterns that have been set early in the firing.
>> With a gas kiln, you can make changes and they have an
>> effect pretty quickly.
Ruth,
You raise an important aspect of wood firing, and I think your point is well
taken. Though I have only fired with wood a few times, it does seem that
once the fire gets headed in the wrong direction, it takes a while to make
corrections. It is much easier to keep things working properly all along.
But to do that, I must really understand how to control the fire.
That is why I am so glad to be getting such great explanations from you and
others about how to regulate the fire using the available controls. As you
point out, it is harder to do this with a wood kiln that a gas kiln. Now
that I understand how to use dampers wisely, I will be able to manage the
fire much more effectively. Trial and error is a good teacher, but
collective wisdom is even better!
I realize from your explanation how the presence of the unburnt wood and
coals could make it difficult to make rapid changes to the draft or the
fire. I think I have experienced this in our firings. At times I have felt
that our stokes were not burning well. We could tell we needed to be
getting more heat in, but just stoking in more wood seems to choke up the
firebox and lead to over coaling. I think if we manage the draft better it
will be easier to fire our kiln. A bit of experimenting with our kiln
remains to be done, but my of the process is much more complete now.
I think that if we learn to manage the fire better we would then be able to
feel comfortable about soaking or lengthening the final stage of the firing.
As it has been so far, we have trouble just getting to temperature, so
maintaining it has not been easy. But I think that using your approach of
managing the fire more effectively all along, we may get more heat out of
less wood. It will still be tricky, but I think I understand better what we
need to do. And I certainly understand better how the various controls can
work to keep the fire doing what we want.
You are right about everyone wanting to check the cones. We use a pyrometer
to gauge temperature trends, so it seems silly to check the cones too often.
But they love looking in. Your suggestion about a small spy hole seems
wise.
Thank you for such clear and insightful information. I appreciate your
help.
Matt
-----Original Message-----
From: Ruth Ballou [mailto:rballou@BELLATLANTIC.NET]
Sent: Wednesday, May 09, 2001 6:14 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: wood kiln design question
Matt,
Using the passive damper is equivalent to decreasing the height of the
chimney. The introduction of air at that point also helps burn up the flue
gases.
I've found that it's important in firing a wood kiln to set up things right
from the start. It's very difficult to change patterns that have been set
early in the firing. With a gas kiln, you can make changes and they have an
effect pretty quickly. If you decide you want to cut the air back, it's
easy to also cut the gas back. With a wood kiln, because you're burning a
solid fuel, any change in the air must take into account the effect on the
coals. A lot of air requires that you stoke a lot of wood. That wood takes
time to burn, building the coal bed. As the temperature climbs the draft
will increase, requiring even more wood per stoke, adding to the coal bed.
Trying to get out of this by cutting the air means the coal bed will burn
slower. The next thing you know, the air is on it's way to being blocked
and the stokes aren't burning well either. As the kiln gets hotter and
hotter, making changes can be like trying to divert a runaway freight
train. It's much better to set the pattern from the beginning, controlling
the air so that you stoke as little wood as possible to get a temperature
rise. Increase the amount of wood in the stoke only when it is clear that
the temperature rise has leveled off. Stokes start burning real fast at
this point. It may not be necessary to increase the air because the chimney
will pull harder anyway as the temperature rises. Increase the air only
when it is obvious that the kiln needs it: the stokes have gotten
progressively larger, there's a heavy and long reduction phase with slow
temperature rise. At this point, I prefer to open the damper some, rather
than increasing the primary air. Since you have a passive damper, you can
start bricking it up. If you're going to use the passives, start with them
in during the preheat phase, when you're establishing draft and want to
hold the heat in, then out by the time you're stoking wood on the grates.
The primary air that was open for preheat should be much less by the time
you're on the grates. Increase the air on the front only when you've done
as much as you can with the chimney. Tiny changes can make a big
difference, so cut up soft brick into slivers. Dont' be surprised if you
end up with just 2 or 3 bricks out on the front. This is just one scenario.
Other settings will work as well, so long as the adjustments remain in
balance.
One thing I've noticed with group firings that can have a detrimental
effect on the outcome is the very human desire to keep checking the cones
or the stoke holes. Open these up as little as possible. Cold air is the
enemy. You should have a door design for the stoke hole that allows the
smallest crack to see the progress. Try to read the cones without fully
removing the brick.
Everyone has suggested extending the firing to get the ash to melt. I've
found that stretching it out to 4 or 5 hours between ^ 8 and ^10 makes a
difference.
That's my take on the big picture. I'm sure you've already discovered to
expect the unexpected in woodfiring .
Ruth Ballou
____________________________________________________________________________
__
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.
dianamp@COMCAST.NET on sun 2 may 04
I can hear the guffaws already.
What do you think about making a catenary arch wood fired kiln
with a bourry box on one side and the chimney on the other?
Why? you might ask.
Because I love catenary kilns.
Don't tell anyone but I call them "girly girl" kilns
because we don't have to mess around with that
nasty angle iron stuff, and welding, etc.
( I know, I know, I should love to weld.)
And catenaries are so much fun to build--
that instant when you pull the form out
and the beautiful arch just stands there,
all by itself, is a thrill.
I can design it so the bourry box isn't leaning, or putting any weight
on the arch form, causing it undue stress.
We can make the throat arch between the fire box
and the kiln a penetrable wall
( like porous bag walls are constructed)
which would still support the thrust of the catenary arch
while allowing the heat, flame and ash through.
Same thing for the flu exit.
Do you think it will work??
Has anyone done it?
Probably.
Thanks.
Diana
Rob Van Rens on sun 2 may 04
Diana,
The kiln you describe has already been built numerous times; Bill Van Gilder
of Burkittsville, MD has constructed a number in this area.
He can be reached at (301) 416-2970, or e-mail to
vangilderpottery@earthlink.net
He may have plans for sale; get in touch with him and see.
Rob Van Rens
Frederick Clay Art Center
5400 Yukon Ct, Unit 500
Frederick, MD 21758
(301) 371-0310
www.frederickclayartcenter.com
----- Original Message -----
From:
To:
Sent: Sunday, May 02, 2004 11:40 AM
Subject: Wood kiln design question
> I can hear the guffaws already.
>
> What do you think about making a catenary arch wood fired kiln
> with a bourry box on one side and the chimney on the other?
>
> Why? you might ask.
>
> Because I love catenary kilns.
> Don't tell anyone but I call them "girly girl" kilns
> because we don't have to mess around with that
> nasty angle iron stuff, and welding, etc.
> ( I know, I know, I should love to weld.)
>
> And catenaries are so much fun to build--
> that instant when you pull the form out
> and the beautiful arch just stands there,
> all by itself, is a thrill.
>
> I can design it so the bourry box isn't leaning, or putting any weight
> on the arch form, causing it undue stress.
>
> We can make the throat arch between the fire box
> and the kiln a penetrable wall
> ( like porous bag walls are constructed)
> which would still support the thrust of the catenary arch
> while allowing the heat, flame and ash through.
> Same thing for the flu exit.
>
> Do you think it will work??
>
> Has anyone done it?
> Probably.
>
> Thanks.
>
> Diana
>
>
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Craig Edwards on sun 2 may 04
Hello Diana: I had a kiln exactly like the one you describe. Fired it
for about 10 years. Worked great. The tricky brick work was building the
throats of the bourry box into the side of the catenary arch. Loved that
kiln, had to tear it down when I sold the farm.
Cheers
Craig Edwards
New London MN
dianamp@COMCAST.NET wrote:
>I can hear the guffaws already.
>
>What do you think about making a catenary arch wood fired kiln
>with a bourry box on one side and the chimney on the other?
>
>Why? you might ask.
>
>Because I love catenary kilns.
>Don't tell anyone but I call them "girly girl" kilns
>because we don't have to mess around with that
>nasty angle iron stuff, and welding, etc.
>( I know, I know, I should love to weld.)
>
>And catenaries are so much fun to build--
>that instant when you pull the form out
>and the beautiful arch just stands there,
>all by itself, is a thrill.
>
>I can design it so the bourry box isn't leaning, or putting any weight
>on the arch form, causing it undue stress.
>
>We can make the throat arch between the fire box
>and the kiln a penetrable wall
>( like porous bag walls are constructed)
>which would still support the thrust of the catenary arch
>while allowing the heat, flame and ash through.
>Same thing for the flu exit.
>
>Do you think it will work??
>
>Has anyone done it?
>Probably.
>
>Thanks.
>
>Diana
>
>
>
David Hendley on sun 2 may 04
Dear Diana, if you think building a firing a wood kiln is
"girly-girl", you are my kind of girl.
Of course you can do this. I've seen plans for something
like this years ago, in Studio Potter magazine, I think.
A cross draft kiln like this will, of course, lend itself to lots
of variation in different areas of the kiln - a hot side and
a cool side, and a flash & ash side and a plainer side.
Just don't listen to anything Mel says. He likes kilns
with flat tops. He can tolerate a sprung arch, but a
cantenary might be too much for him.
David Hendley
david@farmpots.com
http://www.farmpots.com
----- Original Message -----
> I can hear the guffaws already.
>
> What do you think about making a catenary arch wood fired kiln
> with a bourry box on one side and the chimney on the other?
>
> Why? you might ask.
>
> Because I love catenary kilns.
> Don't tell anyone but I call them "girly girl" kilns
> because we don't have to mess around with that
> nasty angle iron stuff, and welding, etc.
> ( I know, I know, I should love to weld.)
>
> And catenaries are so much fun to build--
> that instant when you pull the form out
> and the beautiful arch just stands there,
> all by itself, is a thrill.
>
June Perry on sun 2 may 04
That's a cross draft design - pretty common kiln design.
There's a plan for a sweet, little, single bourry box, cross draft kiln tin
the back Steve Harrison (Harris???)original booklet, "Laid Back Wood Firing"
that can fire to cone 10 in about ten hours.
If you wanted a larger kiln you could still design one with two bourry boxes
on one side, and two throat channels, etc. on one side.
Regards,
June Perry
http://www.angelfire.com/art2/shambhalapottery/
Ivor and Olive Lewis on mon 3 may 04
Dear Diana,
Since you have thought this through your design is sure to work. So
get on with the job and good luck with the first firing event.
Best regards,
Ivor Lewis. Redhill, South Australia
Lee Love on tue 4 may 04
dianamp@COMCAST.NET wrote:
>Because I love catenary kilns.
>Don't tell anyone but I call them "girly girl" kilns
>because we don't have to mess around with that
>nasty angle iron stuff, and welding, etc.
>( I know, I know, I should love to weld.)
>
You don't have to weld angle iron. I thought I invented
something, when I bought metal supports for building shelving at the big
hardware store in Kasama. But I have since seen the same materials used
to build kilns in Japanese pottery magazines.
you can see here:
http://www.livejournal.com/users/togeika/2003/03/13/
and here:
http://www.livejournal.com/users/togeika/2003/03/29/
These are steel and are angle pieces, but with holes
all along the sides. These are bolted together. I am pretty sure
you can find stuff like this in America.
You might look at Jack Troy's book. There is a single
chamber cantenary design in it. You stoke right into the chamber and
not a separate fire box.
Also, there is a wood fire list:
http://groups.yahoo.com/group/WoodKiln/
--
Lee in Mashiko, Japan http://mashiko.org
http://potters.blogspot.com/ Commentary On Pottery
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