Larry Kruzan on tue 27 sep 11
Hi Kathi,
Thanks for telling us about your kiln, it sure confirms the theorem that
there are no "one size fits all" answers.
We all know how much kiln building experience is represented by our
membership, so if there is a answer - I'll bet someone here has a clue. I'm
sure no master kiln builder but there are a few things I'd like to check. I
wonder if you would be willing to share your kilns and flue's dimensions?
There are two areas I'd sure take the closest look at;
The first would be the size and type of burners. If the burner orifice is
undersized you will be starving the kiln at the top. As a part of looking
the burners, I wonder what fuel you are firing with? If the burner orifices=
'
were sized for propane and you are firing with natural gas, the hole will b=
e
undersized causing a reduction in BTU output.
The second thing is the flue. If it is undersized, by even a little, the
firing will slow at the top temp - it's like having the damper partially
"in" all the time. I've seen a kiln where the chamber flue opening was very
small in relation to the burner openings - the two burner openings measured
9" tall and 4.5" wide each - and the chamber/flue opening was 4.5" tall by
9" wide. The Flue inside measured 4.5x9" also.
As soon as we cut the flue open one brick (made it 7" tall x 9" wide) and
restacked the flue with a 9" x 9" opening, the kiln fired MUCH better.
The answer is out there.
Larry Kruzan
Lost Creek Pottery
An armed man is a citizen. An unarmed man is a subject.
>
I've always taken Mel's advice as suggestions for better firings. Some work
for me, some don't. Case in point, fast firing. I've tried this. I can star=
t
my kiln and warm up to about 400 degrees. Then, set it to firing as fast as
I can pump gas and air in. I hit body reduction now in three hours instead
of four and a half. Funny thing though. No matter what I do this kiln takes
about 10 1/2 - 12 hours to fire. As I get toward cone 8 it slows down. On
Mel's advice I cut back the power to the burners. It doesn't matter. This
kiln has a mind of it's own. I can slow fire, fast fire or something in
between. It has decided how long a firing takes and I guess I'll just have
to live with it.
My best advice, listen to what everyone says. Try everything several times.
Find what works best for your kiln. Know your kiln.
KATHI LESUEUR
http://www.lesueurclaywork.com
mel jacobson on tue 27 sep 11
i have never pretended to give advice to
you three. i have learned from you three.
my voice about fast fire is directed at folks that
think `thermal dynamics` is a rock group.
people who think facebook is `critical to my life`.
this thread started with stories about colleges, high schools
art centers that fire for 40 hours...long warm ups, in fact days
of warm up.
if i fill my propane tanks at the farm it costs me $3,000.
that is not chicken feed.
if you fire an electric kiln. today it may be not worth
the pots you have in the kiln. (see: california utility costs.)
i have repaired and fixed kilns that fired for twenty five hours with
a hundred dollars worth of propane, and 80 bucks worth
of pots in the kiln. (i call it sky warming.) and the kiln was built from o=
ur plan.
(of course it was `modified` by someone else to make it
better.) i fix the kiln, rebuild, new stack and fired that kiln
in five hours to cone 10. they would not know the racers from
`bright mother in law blue`. they needed help.
competent professionals should know what they are doing.
however...kevin caufield moved his big car kiln to a rural area...
he had fired it hundreds of times....and when he switched to propane
he could not even make cone 9. guess what? he switched to fast firing
protocol, the one i use, and he now fires that kiln in 9-11 hours.
cone ten perfect. he was pre-warming overnight to about 900F, then
firing in his old way...it stalled. he wasted thousands of dollars in prop=
ane
cost...now he knows.
we have been trying for faster and faster, more efficient and quality kiln
work at our farm for ten years. and the results are outstanding. it gets =
to
be: old stereo, new stereo...hank's stereo with tubes or my digital
recordings. hank will sure tell you his is the best by far...maybe it is.
but, i don't have hank's ear for stereo. it matters not to me.
hell, i think my car stereo is really good...who knew?
many people just want to fire their pots the best way they can.
many cannot get their kiln to make temp, they fuss, they waste, they
fire over and over the same way....poor pots. 40 percent loss.
everyone wants decent, well fired pots...we all do. i am just trying
to give potters a chance to do that. when they grow up, they can
change, adjust, manipulate the kiln to get special results. but, i want
them to hit their cone...as well as they can. now. and long pre/heat
and long firing will do nothing for them except waste fuel.
but, what they do with the kiln during cool down may change their
lives forever.
mel
from: minnetonka, mn
website: http://www.visi.com/~melpots/
clayart link: http://www.visi.com/~melpots/clayart.html
KATHI LESUEUR on tue 27 sep 11
On Sep 27, 2011, at 8:26 AM, mel jacobson wrote:
> i have never pretended to give advice to
> you three. i have learned from you three.
>=3D20
> my voice about fast fire is directed at folks that
> think `thermal dynamics` is a rock group.
> people who think facebook is `critical to my life`......
>=3D20
> <> however...kevin caufield moved his big car kiln to a rural area...
> he had fired it hundreds of times....and when he switched to propane
> he could not even make cone 9. guess what? he switched to fast =3D
firing
> protocol, the one i use, and he now fires that kiln in 9-11 hours.
> cone ten perfect. he was pre-warming overnight to about 900F, then
> firing in his old way...it stalled. he wasted thousands of dollars in =
=3D
propane
> cost...now he knows....
>=3D20
I've always taken Mel's advice as suggestions for better firings. Some =3D
work for me, some don't. Case in point, fast firing. I've tried this. I =3D
can start my kiln and warm up to about 400 degrees. Then, set it to =3D
firing as fast as I can pump gas and air in. I hit body reduction now in =
=3D
three hours instead of four and a half. Funny thing though. No matter =3D
what I do this kiln takes about 10 1/2 - 12 hours to fire. As I get =3D
toward cone 8 it slows down. On Mel's advice I cut back the power to the =
=3D
burners. It doesn't matter. This kiln has a mind of it's own. I can slow =
=3D
fire, fast fire or something in between. It has decided how long a =3D
firing takes and I guess I'll just have to live with it.
My best advice, listen to what everyone says. Try everything several =3D
times. Find what works best for your kiln. Know your kiln.
KATHI LESUEUR
http://www.lesueurclaywork.com
Edouard Bastarache on tue 27 sep 11
Like "Old Albert" would say, it depends on your frame of reference.
I have a standard gaz kiln I built myself not following the standards
for designing gaz kilns. 9 inches IFB for the walls and arch.I added a
high quality Kaowool on top of the arch.
My stack is out of standards but on windy days it draws too much.
But we have a way to lower the velocity by pulling out a brick in the
lower part of the chimney.
My results are very good with losses of 1% at stoneware temp.
On windless days it takes 16 hours to fire. So we count on the
"time factor" and we "shoot the breeze" sitting around.
Money is not a factor for us, good pots are most important.
http://www.youtube.com/watch?v=3Dw2DljC09MB4
Gis,
Edouard Bastarache
Spertesperantisto
Sorel-Tracy
Quebec
http://www.flickr.com/photos/30058682@N00/
http://edouardbastarache.blogspot.com/
http://edouardbastaracheblogs2.blogspot.com/
http://www.facebook.com/edouard.bastarache
David Hendley on tue 27 sep 11
OK Mel, I see where you're coming from.
I have never owned a kiln that had trouble reaching temperature
in a reasonable length of time. It has always been my choice to
speed it up or slow it down, as I see fit. If a small kiln took
40 hours to fire I would not fire it again until things were
changed or adjusted!
David Hendley
david@farmpots.com
http://www.farmpots.com
http://www.thewahooligans.com
----- Original Message -----
> i have never pretended to give advice to
> you three. i have learned from you three.
>
> my voice about fast fire is directed at folks that
> think `thermal dynamics` is a rock group.
> people who think facebook is `critical to my life`.
>
> this thread started with stories about colleges, high schools
> art centers that fire for 40 hours...long warm ups, in fact days
> of warm up.
>
ivor and olive lewis on wed 28 sep 11
Dear Edouard Bastarache,
Congratulations on using a "Passive Damper"
You describe your kiln as being "... a standard gaz kiln I built myself not
following the standards for designing gaz kilns. 9 inches IFB for the wall=
s
and arch. I added a high quality Kaowool on top of the arch."
As I understand the specification for Fibre insulation, it is, in a simple
sense, the mass per cubic metre that defines its insulating quality and the
composition that determines the maximum working temperature. Nils Lou, in
"The Art of Firing" discusses these and explains how to exploit this
knowledge to get a good kiln.
So, what do you mean by "High Quality Kaowool"?
Best regards,
Ivor Lewis,
REDHILL,
South Australia
KATHI LESUEUR on wed 28 sep 11
On Sep 27, 2011, at 11:33 PM, Larry Kruzan wrote:
> Hi Kathi,
>=3D20
> Thanks for telling us about your kiln, it sure confirms the theorem =3D
that
> there are no "one size fits all" answers.
>=3D20
> We all know how much kiln building experience is represented by our
> membership, so if there is a answer - I'll bet someone here has a =3D
clue. I'm
> sure no master kiln builder but there are a few things I'd like to =3D
check. I
> wonder if you would be willing to share your kilns and flue's =3D
dimensions?
Sorry Larry,no flue here. My kiln is a modified Abernathy kiln unique to =
=3D
the Ann Arbor area. What we do is leave three bricks out of the bottom =3D
of the door. Since this is forced air I'm pushing air in not drawing it =3D
out. You can see it on my web site.
> There are two areas I'd sure take the closest look at;
>=3D20
> The first would be the size and type of burners. If the burner orifice =
=3D
is
> undersized you will be starving the kiln at the top. As a part of =3D
looking
> the burners, I wonder what fuel you are firing with.=3D20
I fire natural gas. I have a two inch line coming to the kiln. The =3D
burners are forced air that I made similar to ones I made with JT's help =
=3D
years ago. A two inch pipe with a squirrel cage blower on one end and an =
=3D
Eclipse Sticktite nozzle on the other. Gas is introduced into the pipe =3D
by a street el welded in place. It's been so long that I forget what =3D
size. But, I do have an abundance of gas available.
An interesting fact is that whenI first brought this up from Texas I had =
=3D
to hold it back in the winter. I think part of the problem is that this =3D
kiln was first built in 1982, moved back to Ann Arbor in and rebuilt in =3D
1987, torn down and rebuilt once again when I added on to the studio and =
=3D
brought it inside. After all of that up and down it's not as tight as in =
=3D
the beginning.
>=3D20
> KATHI LESUEUR
> http://www.lesueurclaywork.com
>=3D20
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