mel jacobson on tue 10 may 05
i know mark was pulling a leg a bit, and tiles are nice
in a kiln...but:
remember, much of the modern theory on firing is
to REDUCE the number of pots you fire in each load.
i am giving pots at least a generous finger or thumb
between them. when in doubt increase the air flow
in a kiln, do not restrict it.
it is very bad economy to stack a kiln so full that
you lose 35 percent of your pots. over stacking
is a pot killer. and leave generous spaces between
shelves and posts.
i know...many take pride in `gd lois, i got 85 pots in
a kiln designed for 35...i am a great ecologist.`
bull. you just lost 40 of them. and that loss is
wasting fuel at a great dimension...those that have
to be re fired are wasting fuel. and if you restrict the
air flow kilns will often stall. fire a propane kiln for three hours
on high...with nothing happening....and look at your bill.
at $2.25 a gallon you have just blown 50 bucks.
i watch people load kilns and build heat damns into the
loading. might as well brick up your flue. those twelve pots on
your loading shelf will be happy to wait for the next firing.
don't think of your kiln like a crowded train in tokyo. let everyone
have a seat. same for electric kilns.
mel
from mel/minnetonka.mn.usa
website: http://www.pclink.com/melpots
Craig Martell on tue 10 may 05
mel way saying:
>remember, much of the modern theory on firing is
>to REDUCE the number of pots you fire in each load.
Hello mel:
Ok, but I haven't talked to anyone yet who has actually said this and given
any data to back up the "theory".
My experience has been that my kiln fires better with a good, well packed
load of pots. It doesn't use more gas and it doesn't add time to the
fire. I don't see a higher loss rate from a tightly packed kiln
either. Actually, I see more dunting in kilns, my own included, that are
lightly loaded. There's less of a "thermal mass" in the kiln and it cools
quicker which could possibly lead to dunting.
> when in doubt increase the air flow in a kiln, do not restrict it. it is
> very bad economy to stack a kiln so full that
>you lose 35 percent of your pots. over stacking is a pot killer.
I wonder what the limit is on the number of pots loaded with regard to
reduced air flow. I try and place pots fairly close and the differences in
forms will always allow air passage. All the shelves are staggered in
height and there are provisions made for a non restricted exit flue etc. I
always fill up the shelves with pots and the kiln fires just fine. My loss
rate is below 5%. I'm not exaggerating. Some fires the loss is zero.
My point of view is that with the present price of fuel I will try to load
the kilns as full as possible to cut firing costs per piece. So far, it
has worked just fine. Sometimes I have to fire a light load because of
schedules and deadlines. The gas consumption is about the same for my
kiln with a heavier load of pots.
regards, Craig Martell Hopewell, Oregon
Lee Love on wed 11 may 05
George from California arrived with his workshop folks (he has them at
Furuki-sans for a week before going to Shigaraki) the last day of the
pottery festival, and told me that his wood kiln is firing much better
since he stopped loading it like a gas kiln. The kiln was over reducing,
even with the damper fully open. The tightly stacked work was acting
like a damper. When he started stacking loosely, everything worked
better. His kiln is all hardbrick, except for the two piece fiber door.
It fires in 15 hours (it surprised me, because I thought you would have
to fire longer with an all hard brick kiln.) I will probably use more
hardbrick next build, maybe only putting softbrick in the arch.
Several potters were interested in the design of my wood kiln at the
Mashiko pottery festival. Both LPG and oil are very expensive here and
the cost is making it difficult for potters. My kiln that fires free
waste wood is not effected by the cost of petrochemicals.
>
--
李 Lee Love 大
愛 鱗
in Mashiko, Japan http://mashiko.org
http://hankos.blogspot.com/ Visual Bookmarks
http://ikiru.blogspot.com/ Zen and Craft
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