mel jacobson on sun 12 aug 01
man, what an interesting story.
just talked to kevin caufield, some of you know kevin
and amy, and new baby ian. great folks.
kevin is a seasoned, veteran, full time potter.
knows his stuff.
has a great kiln. works a charm.
it is a nils lou flat top car kiln with an arch.
state of the art johnson natural gas/power burners.
he has built this kiln four times in four locations.
he now has a wonderful home, workshop, kiln room...
perfect rural area.
his new kiln does not work. it stalls, does not reduce
well, slow to make temp. he has gone sorta nuts.
same bricks, same size, same burners, all the same.
won't fire worth crap.
well, yesterday he found the problem.
hold your seats.
when he built the new kiln, he made the slot for the damper a bit
bigger, and the kiln shelf for the damper is a bit smaller. it has
a little room, slides nice.
the gap of maybe 3/8's of an inch above the shelf was working
as a negative damper. he added a piece of kaowool to block that
area and the kiln took off like a rocket.
works just like the old kiln. ten hour firing, good reduction all
through the kiln. nice.
so, it is remindful of people who tell nils, me others. `hell, any
kiln can be fired with the seat of the pants`....well, i have
had my oxyprobe in friends kilns, asked them to adjust the kiln
to perfect reduction as they like it...read the numbers, and the kiln
is not in reduction...smoke all over, no reduction. move the damper
maybe a half inch...open the primary air, turn down the gas pressure
and the kiln is at 6.0 on the oxyprobe. no smoke anyplace.
we have been talking to kevin for 6 months now. nils, me, kurt
others. we thought everything was the same. all the measurements
were the same. but, he just found one gap, not the same.
it was the problem.
what a good learning story. he said to me just now on the phone...
`hey, let people know, this is not embarrassing, let folks learn
from this.` so i am doing just that.
mel
From:
Minnetonka, Minnesota, U.S.A.
web site: http://www.pclink.com/melpots
Earl Brunner on sun 12 aug 01
Yeah, I've built a couple of kilns and thought they fired well, I
always had brick up doors, and I never sealed the cracks with clay
before firing.
I now have a Geil kiln, wasn't in a situation to build this time. This
kiln has a digital pyrometer. What an eye opener! 1/4 of an inch
movement on the damper makes the difference between smooth even climb in
temperature and a stall. I knew it could be tricky, but had no idea it
could be that tricky.
mel jacobson wrote:
> man, what an interesting story.
>
> just talked to kevin caufield, some of you know kevin
> and amy, and new baby ian. great folks.
>
> kevin is a seasoned, veteran, full time potter.
> knows his stuff.
> has a great kiln. works a charm.
> it is a nils lou flat top car kiln with an arch.
> state of the art johnson natural gas/power burners.
> he has built this kiln four times in four locations.
> he now has a wonderful home, workshop, kiln room...
> perfect rural area.
>
> his new kiln does not work.
>
> when he built the new kiln, he made the slot for the damper a bit
> bigger, and the kiln shelf for the damper is a bit smaller. it has
> a little room, slides nice.
> the gap of maybe 3/8's of an inch above the shelf was working
> as a negative damper. he added a piece of kaowool to block that
> area and the kiln took off like a rocket.
> works just like the old kiln. ten hour firing, good reduction all
> through the kiln. nice.
>
--
Earl Brunner
http://coyote.accessnv.com/bruec/
bruec@anv.net
Hank Murrow on sun 12 aug 01
Dear Mel;
It IS a great story, and generously shared. Thanks. I can't tell
you how many times potters have called me up with similar tales, to find
the gremlin sooner or later to their embarrassment and education. Can't
assume anything. Look, record, think, draw, make sense of it. Great post,
Hank
>man, what an interesting story.
>
>just talked to kevin caufield, some of you know kevin
>and amy, and new baby ian. great folks.
>
>kevin is a seasoned, veteran, full time potter.
>knows his stuff.
>has a great kiln. works a charm.
>it is a nils lou flat top car kiln with an arch.
>state of the art johnson natural gas/power burners.
>he has built this kiln four times in four locations.
>he now has a wonderful home, workshop, kiln room...
>perfect rural area.
>
>his new kiln does not work. it stalls, does not reduce
>well, slow to make temp. he has gone sorta nuts.
>
>same bricks, same size, same burners, all the same.
>won't fire worth crap.
>
>well, yesterday he found the problem.
>hold your seats.
>
>when he built the new kiln, he made the slot for the damper a bit
>bigger, and the kiln shelf for the damper is a bit smaller. it has
>a little room, slides nice.
>the gap of maybe 3/8's of an inch above the shelf was working
>as a negative damper. he added a piece of kaowool to block that
>area and the kiln took off like a rocket.
>works just like the old kiln. ten hour firing, good reduction all
>through the kiln. nice.
>
>so, it is remindful of people who tell nils, me others. `hell, any
>kiln can be fired with the seat of the pants`....well, i have
>had my oxyprobe in friends kilns, asked them to adjust the kiln
>to perfect reduction as they like it...read the numbers, and the kiln
>is not in reduction...smoke all over, no reduction. move the damper
>maybe a half inch...open the primary air, turn down the gas pressure
>and the kiln is at 6.0 on the oxyprobe. no smoke anyplace.
>
>we have been talking to kevin for 6 months now. nils, me, kurt
>others. we thought everything was the same. all the measurements
>were the same. but, he just found one gap, not the same.
>it was the problem.
>
>what a good learning story. he said to me just now on the phone...
>`hey, let people know, this is not embarrassing, let folks learn
>from this.` so i am doing just that.
>mel
>
Charlie and Linda Riggs on mon 13 aug 01
Mel,
Does this story sound familiar. Our "co-op" wood kiln group (5 owners) built a
two-chambered climbing kiln following the plans outlined by Ruggles and Rankin
which was printed in The Studio Potter---well, kind of followed the plans.
What seemed to be small changes due to "creative thinking" turned into major
changes in the way the kiln fired. The darn thing just didn't want to fire like
the one at Penland or the NC Pottery Center.
After number brutal firings some lasting up to 36 hours, the collective brilliance
of the group came up with firing compensations for the changes in
structure....and what a difference.
The firing time is now a nice easy 14-15 hours and we even like each other when we
are finished firing.
And Kevin is right, it's not embarrassing....it's a real learning experience about
subtleties of wood kilns and atmospheric firings...and a lot of learning about
oneself.
Linda Riggs
In hot and steamy NC where the forest spiders are spinning webs with such joyful
abandon that you have to carry a long stick and conduct an orchestra to walk in the
woods.
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