Karen Terpstra on sat 2 nov 02
Here is a follow up of my previous post on "wood firing in an urban =
area."
I became aware of the importance of controlling the amount of flame and =
smoke emitting from the stack while firing on campus in the middle of =
Iowa City at the U of IA. Chuck Hindes the professor there was always =
mindful of complaints from on or off campus. It was his goal to learn =
how to fire an anagama or chamber kiln without more than one and a half =
feet of flames coming out of the chimney. =20
Despite what I have heard from some narrow minded people who told me, =
"it can't be done." It IS possible! Having this urban situation has =
determined what kind of wood that I can use and the over engineered =
design of our chimney. This in turn has determined what type of work and =
"look" we can achieve with this kiln and this environment.
Some of this is wood firing 101 but it's important for beginners or =
anyone thinking about building a wood kiln to know. We use oak because =
it burns clean and without all of that heavy black smoke. (There is =
lots of pine and oak available here.) The other reason I LOVE oak is =
because I'm 48 years old I like to sit in my chair and relax between =
stokes! It takes longer to burn and requires PATIENCE to let it burn, =
but if you learn the stoking rhythm between the oak and with what your =
kiln requires it makes for very easy firing.
We have passive dampers at the base of the chimney, 4 feet up the =
chimney from that and another row 2 feet up from that (those are the =
ones we use most). If there is too much flame coming out of the chimney =
we pull a few more bricks out of the passives to control it. With our =
kiln and with using oak, we have learned that any more than 1 to 2 feet =
of flame from our stack wastes allot of heat and energy. If there's one =
thing I can't stand its wasted energy and wood!
We did a pine firing one summer during a time when no one was on campus. =
I was granted permission from the physical plant and made them aware =
that there would be much more smoke than usual. I wanted to try it just =
for comparison and curiosity's sake.
I will never do it again. We had to stoke more than twice as often than =
with oak because it burns so fast. We were constantly cleaning the =
mouse holes. Way to much work for me!!!! Even the young energetic =
student complained.
If the barometric pressure was low, we were breathing emissions that =
actually gave me a headache. At the end when we loaded up the kiln prior =
to shut down, there was a fireworks display of 5 feet of flame and =
sparks like you would not believe.
Another reason we fire with oak is because of it's "clean" firing. We =
have an undergraduate program here and the majority of the students work =
is functional. Dirty drippy snotty effects are gorgeous on the right =
type of work but in our situation, the students and I are satisfied =
with going after the "flash" with just a "kiss of ash" as they call it. =
We fire for 30 to 36 hours. We don't have to stir the wood in the =
firebox (that's another thing that allows me to just sit in my chair =
just a bit longer.) Occasionally we peek in the firebox and may have to =
turn a big log over with the poker occasionally if we have a clunker. We =
rarely have to do all that bending over to clean mouse holes. We end up =
with abuot a bucket or so of ash at the end of the firing. On a good =
firing, 2 cords of wood or less for a 36 hour firing. That's really =
efficient for us.
If a guest tells me that "you have to stir....blah, blah, blah...." and =
proceeds to do it, that guest does not come back. My students and I =
know that too much ash on our functional stuff makes for dirty runny =
pots. I know that is an admirable aesthetic for some people. What I'm =
trying to convey here is that often times you can not have it all in one =
wood kiln. You have to make choices and work with the wood you have and =
the firing situation that works for you and the area you live in.
I love to look at ashy, drippy, snotty pots. But, the type of firing we =
do here doesn't allow it. I try to find situations for myself and a few =
advanced students in other people's kilns that are different from ours =
for the variety of the aesthetic and the experience of different =
situations and kilns.
A beginning student asked me last week during our firing, "how long does =
it take to learn wood firing?" "A life time." I replied. An advanced =
student nodded in agreement. It's taken me lots of trial and error, =
research, many many conversations with mentors to learn how to fire in =
this situation. And I'm still learning something with every firing. =
There are still variables to deal with every firing.... the expertise of =
the crew, the weather, how the kiln is stacked, etc. Always something. =
We are a crazy lot aren't we!
Happy firings,
karen terpstra
La Crosse, WI
David Hendley on sat 2 nov 02
I also choose oak for firing my kiln, if I have a choice of woods.
At the pallet factory they use oak, pine, sweet gum, and elm.
Any and all are OK, but pine makes thick black smoke from the
resin, plus the coals do not want to break apart and fall through the
grates, and then they are not as hot in the coal bed.
Sweetgum is heavy when wet, but then very light when dry. That
means you do all the work to load, transport, and stack heavy boards,
and then you don't get much heat value for your work from the
light-weight wood. Oak is heavy when wet and also when dry and
has the most heat value per volume of wood.
I can't understand why many books and articles state that pine
is the preferred wood for firing a kiln.
No matter what you do, you will make smoke when firing a wood
kiln, even if it is just an occasional mistake cause by over-stoking.
I would say that I produce more smoke per year with the air-tight
stove that heats my house than with my wood kiln.
The stove is used about 100 days a year and the kiln about 15 days
a year.
The chimney on my kiln is 16 feet high. At the top end of a firing
there will be flame several feet out the top of the chimney. If that
concerned me, I would simply make the chimney taller.
David Hendley
Maydelle, Texas
hendley@tyler.net
http://www.farmpots.com
----- Original Message -----
I became aware of the importance of controlling the amount of flame and
smoke emitting from the stack while firing on campus in the middle of Iowa
City at the U of IA. Chuck Hindes the professor there was always mindful of
complaints from on or off campus. It was his goal to learn how to fire an
anagama or chamber kiln without more than one and a half feet of flames
coming out of the chimney.
John Baymore on sun 3 nov 02
Karen,
Yes...yes....YES! It is great to hear someone else talking about creatin=
g
less smoke in woodfiring. I too have been on that "crusade" for about 30=
years. Thank you so much for posting your thoughts on this subject. =
Excellent post. And thanks for the other posts commenting on the Beecher=
case too. And for sending some financial support for her legal battles.=
It was his goal to learn how to fire an anagama or chamber kiln without
more =
than one and a half feet of flames coming out of the chimney.
Despite what I have heard from some narrow minded people who told me,
"it can't be done." It IS possible! =
Of course it is! Those same types of people will tell you that in cerami=
cs
you ALWAYS have to do "X" in order to get "Y". Hence the great
perponderance of "ceramic myths" . In most cases........ ain't true. =
Personal preferences that they have turned into "rules". =
I fire a four chamber (five, if you count the dogi) on pine and hemlock a=
nd
unless I WANT it....... I don't have ANY flame out the stack. Yeah....ev=
en
with pine. That is managed mainly by the stoking pattern..... basically
less wood more often. Also a good firebox design that promotes good
aeration and mixing. =
For the first 16 hours of my typical 24-26 hour firing you wouldn't know
that my kiln is "on" from looking at the chimney. Not even as much smoke=
as a typical fireplace or wood stove out the chimney. In general even
after that..... I produce less smoke than is typical for most wood fire
kilns I have seen and typically NO flame out the chimney top.
Yes... I'll admit to occaasionally putting on a "fireworks display" for a=
visitor......... putting a big column of fire out the chimney. Very
dramatic that you can stuff that wood in the dogi....... and all that way=
back at the chimney...... there is the flame front burning off! OK.....
all wood fire-ers have a little streak of pyro, don't they?
I run workshops here every summer (since 81) and the differences in smoke=
and flame created by more inexperienced stoking ....... exact timing,
amount (wt.) of wood, surface area of the pieces, where the wood is throw=
n,
and so on....... is READILY evident on the kiln. Learning and skill
development is an important factor.
Having this urban situation has =3D
determined what kind of wood that I can use and the over engineered =3D
design of our chimney. This in turn has determined what type of work and =
=3D
"look" we can achieve with this kiln and this environment.
.............................................. We use oak because =3D
it burns clean and without all of that heavy black smoke. =
Yes.... different woods produce differing amounts of smoke....and is a go=
od
first place to "go" for someone who is having a smoke problem. The
different woods produce different qualities to the ash deposits too.
We have passive dampers at the base of the chimney, 4 feet up the =3D
chimney from that and another row 2 feet up from that (those are the =3D
ones we use most). If there is too much flame coming out of the chimney =
=3D
we pull a few more bricks out of the passives to control it. With our =3D=
kiln and with using oak, we have learned that any more than 1 to 2 feet =3D=
of flame from our stack wastes allot of heat and energy. If there's one =
=3D
thing I can't stand its wasted energy and wood!
My noborigama also uses passive dampers for draft control. They are in a=
n
array across the flue collection box that ducts the five exit flues from
the last chamber into the single chimney. They are about 2 feet above th=
e
level of the exit flues coming out of the last chamber. There is also on=
e
larger one on the chimney about four feet up. In general, as the firing
progresses from the dogi to the chambers heading back along the kiln.....=
.
the more open they are. This also helps burn off the unburned gases once=
the chimney is at ignition temperature.
The larger port located on the chimney is above the slab damper that is
used to seal the kiln at the end of the firing. This allows me to shut t=
he
draft flow thru the kiln down....... and then fully open the passive damp=
er
hole above the sealed damper..... thereby drawing cold air in thru that
port.... and rapidly cooling down the upper part of the chimney that pass=
es
through the kiln roof structure. Helps cut the danger of a fire at the
roof penetration point.
We did a pine firing one summer during a time when no one was on campus. =
=3D
I was granted permission from the physical plant and made them aware =3D=
that there would be much more smoke than usual. I wanted to try it just =
=3D
for comparison and curiosity's sake.
I will never do it again. We had to stoke more than twice as often than =
=3D
with oak because it burns so fast. We were constantly cleaning the =3D
mouse holes. Way to much work for me!!!! Even the young energetic =3D
student complained.
If the barometric pressure was low, we were breathing emissions that =3D
actually gave me a headache. At the end when we loaded up the kiln prior =
=3D
to shut down, there was a fireworks display of 5 feet of flame and =3D
sparks like you would not believe.
See above...... it can be done. But it takes very careful fire managemen=
t.
And I am sure that some kiln's fireboxes won't allow it to work as well.=
=
I can also put 10 feet of flame out my chimney and make it look like an o=
ld
coal fired steam engine if I want to...... simply by stoking heavier. I'=
ll
certainly agree that the pine takes more stoking than any hardwood though=
.
A beginning student asked me last week during our firing, "how long does =
=3D
it take to learn wood firing?" "A life time." I replied. An advanced =3D=
student nodded in agreement. It's taken me lots of trial and error, =3D
research, many many conversations with mentors to learn how to fire in =3D=
this situation. And I'm still learning something with every firing. =3D
There are still variables to deal with every firing.... the expertise of =
=3D
the crew, the weather, how the kiln is stacked, etc. Always something. =3D=
We are a crazy lot aren't we!
Ah yes...... so well said!!!!!!!! Maybe 10 lifetimes .
Best,
..............................john
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA
603-654-2752 (s)
800-900-1110 (s)
JohnBaymore.com
JBaymore@compuserve.com
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