Rusty Sieck on wed 9 oct 96
Hi all,
I just fired my new (new to me) olson 24 kiln. I've never really fired
an updraft kiln before, so I wasn't really expecting too much from the
first load. The kiln fired pretty well - the temperature was quite even
top to bottom and back to front, but the reduction was real spotty (good
reduction in some places, none in others). I started reduction at 900 C
to reduce the body and continued in various degrees of reduction to the
end of the firing. One side reduced better than the other, and the
atmosphere overall seemed rather stratified.
Anyway, what I'm wondering, is whether anyone out there who fires an
updraft kiln in reduction could help me out a little with techniques -
It would be great to get a little help and not have to "blindly
experiment" with another load...Primary air, damper positions and
pressure levels would be greatly appreciated...My thoughts and theories
about the failings of this firing include the possibilities of primary
air (more or less), and damper position - perhaps I was too
conservative. Any help would be greatly appreciated - thanks in
advance!
Rusty Sieck
Making a french drain around my barn with my "first load shards" - makes
me think of the "hammer" discussion of some months ago!
Dannon Rhudy on wed 9 oct 96
>----------------------------Original message----------------------------
>Hi all,
>
>I just fired my new (new to me) olson 24 kiln. I've never really fired
>an updraft kiln
Rusty,
An updraft is what I have to fire, and while it is not an Olson the set-up is
much the same, and I've fired Olsen's before. The probability is that you
did have too much air intake at the burners, and that your damper may
have been a bit too open. Since I have neither pyrometer nor oxygen
probe, I fire by ear and eye; with practice results are pretty consistent.
I have found best and most consistent results to come from bringing the
kiln up slowly to body reduction, to keep the heat even; putting it into
fairly heavy reduction at that point by use of increased fuel and adjusting
the damper. Then readjust the damper to a slightly more open position
to decrease reduction ( I keep just very light reduction going for the remainder
of the firing, but that is a personal idiosyncracy), increase the gas pressure
a bit, and do the rest of the firing by damper adjustment only. It makes
for a slower firing, which I prefer for glaze reasons, but keeps the kiln even
and the reduction fairly even too.
The truth is that you MUST experiment until you learn your own kiln. It
can be a bit frustrating, but you'll learn more than anyone can TELL you.
(You know that old saying about if you try a hundred times until you
finally get it right, you've learned a hundred things. If you get it right the
first time, you've only learned ONE thing).
Dannon Rhudy
Dannon Rhudy on wed 9 oct 96
>----------------------------Original message----------------------------
>Hi all,
>
>I just fired my new (new to me) olson 24 kiln. I've never really fired
>an updraft kiln
Rusty,
And I failed to address the TIME issue. You did not say how quickly or
otherwise you fired your kiln. Updrafts can really run away with you,
and when they do they tend to have hot/cold spots and uneven re-
duction.
I don't want to bore everyone witless, so email me privately if you
have really specific questions.
Dannon
Louis Howard Katz on wed 9 oct 96
Spotty reduction in our Olsens seems to be only corrected by closing the
damper more to increase backpressure. It could be that you could
compensate in differenet areas of the kiln by closing the bells a bit in
the areas that oxidize, but I haven't found this helpful. Make sure that the
burners are
all clear of shards, flakes of kiln wash and insect nests before loading.
Louis
***************************************************
*Louis Katz lkatz@falcon.tamucc.edu *
*Texas A&M University Corpus Christi *
*6300 Ocean Drive, Art Department *
*Corpus Christi, Tx 78412 *
*Phone (512) 994-5987 *
**************************************************
Wendy Hampton on wed 9 oct 96
Hi,
Not having fired a gas kiln at all I was interested in knowing what is the
body reduction point? I am looking into having a gas kiln in the near future
and I'm sure this information will be valuable.
Thanks
Wendy from Bainbridge Island
Talbott on thu 10 oct 96
>----------------------------Original message----------------------------
>Hi,
>Not having fired a gas kiln at all I was interested in knowing what is the
>body reduction point? I am looking into having a gas kiln in the near future
>and I'm sure this information will be valuable.
>Thanks
>Wendy from Bainbridge Island
body reduction starts at about 900 degrees Celsius--Marshall
Marshall Talbott
Pottery By Celia
Route 114
P.O. Box 4116
Naples, Maine 04055-4116
(207)693-6100 voice and fax
clupus@ime.net
Dave and Pat Eitel on thu 10 oct 96
>----------------------------Original message----------------------------
>Spotty reduction in our Olsens seems to be only corrected by closing the
>damper more to increase backpressure. It could be that you could
>compensate in differenet areas of the kiln by closing the bells a bit in
>the areas that oxidize, but I haven't found this helpful. Make sure that the
>burners are
>all clear of shards, flakes of kiln wash and insect nests before loading.
>Louis
Louis' comments reflect my own experience with an Olsen updraft which I
fired for several years. I didn't really understand how it worked until at
Penland I saw the smoke coming from the wood kiln when it was
reducing--which gave me the idea that I wasn't reducing the Olsen nearly
enough. I used to go for lots of back pressure and some smoke, which lots
of people say is bad and wasteful. It may be, but the pots came out
well--and it was really the only way I could get consistently good
reduction.
Later...Dave
Dave Eitel
Cedar Creek Pottery
Cedarburg, WI
daveitel@execpc.com
http://www.digivis.com/CedarCreek/home.html
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