Andrew Gardner on tue 8 oct 02
My friend and co-conspirator has built and rebuilt a small tunnel kiln
about six times and we still stall out at about 2000 degrees. Doesn't seem
to matter what the stoke pattern is, active damper setting, passive damper
setting, chimney height, cross-section, firebox size, primary air,
secondary air, ember bed size...you name it, we've tried it all. The only
thing I can think of is the firebox is laid up dry, no mortar, and as we
approach 2000 the cracks become quite large. Is it possible we're simply
introducing too much cold air through the cracks (too much primary and
secondary air) and chilling it down too much? Any suggestions? When I get
my film developed I'll post a picture of the set up. Many thanks. My
fast-fire works great, thanks to everyone's help.
Andy
abg@epix.net
Tony Ferguson on wed 9 oct 02
Seal your cracks. You don't want any air coming into the fire box that you
can not control. Take a picture of the back of your kiln, interior, and
send it to me--also a picture of the front, exterior. Also, what kind of
wood and humidity as well as dew point when you fired. If you can find out
the barometric pressure, that may be useful as well.
Thank you.
Tony Ferguson
On Lake Superior, where the sky meets the Lake
Anagama fired Stoneware, Porcelain, Raku
www.aquariusartgallery.com
218-727-6339
315 N. Lake Ave
Apt 312
Duluth, MN 55806
----- Original Message -----
From: "Andrew Gardner"
To:
Sent: Tuesday, October 08, 2002 8:09 PM
Subject: Woodfire kiln stalling
> My friend and co-conspirator has built and rebuilt a small tunnel kiln
> about six times and we still stall out at about 2000 degrees. Doesn't
seem
> to matter what the stoke pattern is, active damper setting, passive damper
> setting, chimney height, cross-section, firebox size, primary air,
> secondary air, ember bed size...you name it, we've tried it all. The only
> thing I can think of is the firebox is laid up dry, no mortar, and as we
> approach 2000 the cracks become quite large. Is it possible we're simply
> introducing too much cold air through the cracks (too much primary and
> secondary air) and chilling it down too much? Any suggestions? When I
get
> my film developed I'll post a picture of the set up. Many thanks. My
> fast-fire works great, thanks to everyone's help.
> Andy
> abg@epix.net
>
>
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iandol on thu 10 oct 02
Dear Andrew Gardner,
I probably did not read earlier posts relating to your problem.
The thought that your are getting additional air in because the bricks =
are unmortared can be corrected by washing the area with a good =
refractory paste which will give a temporary seal at the joints.
There is a good section in Leech's book about the proportions for a kiln =
to get a good firing and I'm sure additional material from Nils Lou and =
Olsen would add to this knowledge.
One final thought. Have you tried a different wood, one with a long =
flame. Or tried splitting your wood into thinner sections so that there =
is a greater surface area available for combustion. Stalling seems to =
indicate inefficient burning and a large ember bed may be an indication =
of this.
Best regards,
Ivor Lewis.
Kabir Syed on thu 10 oct 02
>Lots of ?'s come to mind, primarily like, what kind of wood r u burning,
>is the kiln on a flat ground, or on an incline, is the firebox choked out
>at 2000 (i.e. lots of reduction smoke, and black colder coals), also how
>long have you fired (or tried to fire as the case may be!) after reaching 2000.
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