Peter Willis on tue 26 aug 97
Hello clay artisans,
I am happy to report that we have just completed our Olsen Fast Fire Wood
kiln. We finished it on Saturday and fired on Sunday. Readjusted on
Monday, and fired again on Monday evening.
We figured out the major problems with the first firing. I.E. we stacked
the shelves all wrong and air flow was nil to none so we only made ^5 in
8 Hours. We corrected the stack and extended the chimney and yesterday
we got ^10 in 12 hours. We know that we have to figure out our stoking
pattern and I think we need to raise the chimney some more. I was
wondering if there might be other options for reducing the time. Olsen
fast fires are supposed to go FAST(the book proposes 3 and a half hours)
Our kiln is almost the same size as the example kiln in The Kiln Book but
12 hours is far too long. I would like to bring the firing time to at
least half or less, any suggestions anyone?
Thankfully yours,
Dirty, smelly, tired, but Happy,
Becky Lowery
LOWELL BAKER on wed 27 aug 97
Becky:
What is the hurry? 12 hours is a fast firing to cone ten. How fast
would you fire with gas or electricity? Certainly no faster.
You can hook my sawdust burner to it and blow the roof off but i
think you would like nice glazes, which take time.
W. Lowell Baker
The University of Alabama
David Hendley on wed 27 aug 97
Becky, there are so many variables, but here are some thoughts.
I have several year's experience with fast fire type kilns.
Is the wood dry? And I mean DRY.
Is the wood kindling size (not too big)?
Is there plenty of space under the grates for airflow? I have to
periodically remove some of the coals to keep the passageway open.
Does the burned wood break up and fall through the grates pretty soon after
it is charcoal? If it doesn't the grate bars could be too close together.
You say your kiln is "almost" the same size as the plans in the book. If it
is bigger the flue and chimney need to be bigger.
How tall is your chimney? A wood kiln needs a good stack. Mine is 13 ft.
Is the chimney tight, no spaces to let air through and lose draft? If you
see a lot of fire through the cracks fill them in. Fiberglass insulation
will work.
Stoke aggressively. Add more wood sooner than you think it needs it.
Billowing black smoke is, of course not good, but expect smoke and fire out
the chimney.
Stack the pots loosely, plenty of space for the fire. I have almost no
bagwall. Visualize pathways the fire will take through the stack.
There are some photos of firing my kiln on my homepage. Take a look to see
what I mean by fire coming out the chimney, to see the size of wood I use,
and so on.
http://www.sosis.com/hendley/david/
Best of luck,
David Hendley
Maydelle, Texas
At 02:31 PM 8/26/97 EDT, you wrote:
>----------------------------Original message----------------------------
>Hello clay artisans,
>I am happy to report that we have just completed our Olsen Fast Fire Wood
>kiln. We finished it on Saturday and fired on Sunday. Readjusted on
>Monday, and fired again on Monday evening.
>We figured out the major problems with the first firing. I.E. we stacked
>the shelves all wrong and air flow was nil to none so we only made ^5 in
>8 Hours. We corrected the stack and extended the chimney and yesterday
>we got ^10 in 12 hours. We know that we have to figure out our stoking
>pattern and I think we need to raise the chimney some more. I was
>wondering if there might be other options for reducing the time. Olsen
>fast fires are supposed to go FAST(the book proposes 3 and a half hours)
>Our kiln is almost the same size as the example kiln in The Kiln Book but
>12 hours is far too long. I would like to bring the firing time to at
>least half or less, any suggestions anyone?
>Thankfully yours,
>Dirty, smelly, tired, but Happy,
>Becky Lowery
>
>
David Hendley
Maydelle, Texas
See David Hendley's Pottery Page at
http://www.sosis.com/hendley/david/
The Slack-DeBrock Family on wed 27 aug 97
Hi Becky...I had Fred Olsen come out here to northern wisconsin 2 summers
ago and do a week long workshop building a fastfire woodburner. It is very
consistent and reliable, and it probably has to do with the master
supervising the whole works! I can easily fire it to cone 10 in 6-7 hours
but I slow it down to get more ash and the glazes look nicer in a 8-9 hour
firing. There are some variables and maybe it would be best to talk
directly via phone or e-mail on all of the things you could try. Just for
information, I do offer woodfiring workshops here where we cover the kiln
design, the firing process and glaze/ash effects.
They run 3 days and people seem to learn quite a bit! Let me know if you
would like to be on the mailing list for upcoming ones.
I'd be happy to talk with you about the kiln and what works for me.
Joan Slack-DeBrock/River Run Pottery
P.O.Box 95
McNaughton, WI 54543
715-277-2773
riverrun@newnorth.net
David Hendley on wed 27 aug 97
I hardily disagree, Lowell.
This is a pretty small kiln. 12 hours is not fast.
The 3 or 4 hours Fred Olsen talks about doesn't seem like a good idea to
me, but 7-8 hours is a reasonable goal for speed AND nice looking glazes.
Not much ash build up, but richer glazes than a gas kiln would produce.
David Hendley
Maydelle, Texas
At 01:04 PM 8/27/97 EDT, you wrote:
>----------------------------Original message----------------------------
>Becky:
>
>What is the hurry? 12 hours is a fast firing to cone ten. How fast
>would you fire with gas or electricity? Certainly no faster.
>
>You can hook my sawdust burner to it and blow the roof off but i
>think you would like nice glazes, which take time.
>
>W. Lowell Baker
>The University of Alabama
>
>
David Hendley
Maydelle, Texas
See David Hendley's Pottery Page at
http://www.sosis.com/hendley/david/
Malone & Dean McRaine on sun 31 aug 97
Aloha Becky and all:
I built one of those fastfire dudes. Fired to ^10 in 8-9 hours (after
preheating) except the first time-6 1/2 hrs...(!!??) Had it for years, many
great pots, lots of fun to fire. It's still there in Winlock, Wa.
The short answer is draft is everything.
Check your wood first, I used dry dry cedar 1"x1"x24". Fully stoking one
side would take about 3 min to burn to embers and start to empty the grate.
It burns fast and hot. Heavier woods have more btu's but burn too slow if
you don't split them really small. If your wood is slower than this it's
probably not split small enough. You get the most temp gain in neutral
atmosphere so learn to balance the constant Swing from oxidation to
reduction and back and don't let it go too far either way, a pyrometer will
help cause you'll see the temp dive if you blow it. I didn't have an
atmosphere sampler but it would help to get a feel for The Swing. Also make
sure the pit under your grates stays clear, no more than half full of
ash/embers. Rake it out if it's fuller than that.
I read Olsen's narrative about 20 times and then called him, he was real
helpful and available.
It took me a long time to figure out why the first firing went so much
faster. I finally realized that the bricks, especially in the chimney were
tightly packed but loosley stacked when I built the kiln-I used no morter.
So the heat expansion from the first firing left small gaps between the
bricks after they cooled. Those gaps leaked air and reduced the draft
capability of the chimney even though I added some height to my chimney.
This same brick expansion trick created air leaks in the worst possible
place-around the damper. If I ever build another one I would seal the
chimney but good and tighten up around the damper as best I could.
Another possibility is that your flue sizes are off-(draft is everything.)
I also suggest putting kiln gaurdians on top for each firing.
Have fun and let me know how you do.
Dean
Kauai's hot.
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