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woodfired raku

updated tue 4 jan 05


julene on sat 22 mar 03

Having played with clay for many years, I finally decided a couple years =
ago that it was time to learn to fire some pots. I throw pots, because =
I enjoy throwing and working with the clay, but never felt much of a =
need to make these exercises last forever. Being like many that have =
been influenced by the educational systems, I had taken on the idea that =
one would need alot of equipment to make great perminent pots.

As my family has chosen a lifestyle of voluntary simplicity, and =
although I have a great life, there was not the space or allocated =
resources for these types of expenditures. After living in a very =
natural setting for a few years, I realized that many of the women =
potters that came before me made some of the most enduring pots with =
much less that I. That great pots can be, and possibly, should be the =
fruits of our daily lives.

I do have an extra advantage in that I purchased a RK2 and a used =
paragon kiln over twenty years ago. These were used little before going =
into storage in the family barn while I worked on building a life and =
setting down roots. With the help of Paragon, the electric kiln is now =
wired up and firing bisque and cone 6 oxydation with its original =
elements. Never had a problem with the RK2, just wondering how to =
grease it if it needs greasing. =20

As I live at the source for much of the wood being harvested, it is my =
intention to use this resource for the firing of my pots. I started =
with and have areas for primitive type firings. I plan on slowly =
learning the firing process and raising the temperatures as I am able. =
I did take a woodfiring workshop last year and came away with some great =
pots from a very difficult firing that was barely able to reach cone 9. =
It was a great kiln, but nobody was there that knew how or were willing =
to help fire it. I will be more careful in choising workshops.

Last fall I took Karen Terpstra and Steven Branfman up on their generous =
offer to attend a raku workshp at the University of La Crosse. After =
all these years playing with clay, I had never seen anyone fire rakuware =
and wanted to experience it done by the best. The workshop was great and =
it was wonderful to experience the process done by somebody that was so =
knowledgeable. Karen, her husband, and the students were so hospitable. =
Students looking for a college experience where they'd have the =
opportunity to play with clay and fire a woodkiln could not ask for a =
better place to spend a few years then La Crosse. The area is beautiful =
with many geological features. The meeting in June should be an event =
well worth putting on ones calendar. Thank you again Steve and Karen.

I am finally contributing to the discussion, because I am looking for =
some advice on firing a woodfired raku kiln. It is my belief that it =
would be a fun step in learning to fire with wood and appeared to be so =
easy. I have collected some materials to build kilns with. My =
Valentine's gift was 50 hardbricks, as that was all that my husband =
thought the shocks on the car could handle. I built a temperary a kiln =
similar to the one that Nesrin During uses, but used the hardbricks from =
Alsey Refactories Co as I can get these locally instead of the =
insulating bricks. Has anybody had experience working with their =

I built a solid base of common light colored bricks (two rows thick), on =
which I put the metal front of a dryer with the doorhole for the grate =
opening. The hardbricks were stacked up inside of the dryer drum and =
four 26" half-round shelves were used for the lid. It looked and seemed =
to fire well, but I could not get it up to temperature. I tried to =
rebuilding with a larger firebox similar to the design that Steven has =
in his book, but still did not get up to temperature.

1. Does using the insulating bricks make that much of a difference even =
at raku temperatures? I thought as the Bath Potters were able to reach =
cone 10 with common bricks, I could get it to work for a raku kiln. =
Could the base be hardbricks and the firechamber insulating bricks?

2. I have numerous piles of sticks from clearing the woods. The larger =
wood is stacked to heat the cabin. I thought that these would work for =
the raku kiln. Does one need to use the split wood? I have an almost =
unlimited supply of pine that needs to be cut and split, but wanted to =
use the piles as they are an easy available wood source. The kiln can =
either be built next to them, or the pile can easily be moved by the =
pickup truck. I haven't wanted to run the chainsaw until my son is old =
enough that my attention could be on what I am doing and not him. I =
would use this and oak for a more perminent higher temperature kilns. =
Slapwood and sawdust are also readily available if one wants to haul =
them back to the forest. =20

3. I used the metal from the dryer as I thought that it would add some =
protection and stability, but would it act more as a large heat sink? =
Does building too solid of a raku kiln give more of a heatsink than =
added benefit? =20

4. How large of a vent hole does one need at the top of this type of a =
structure? Are the 5/8" kiln shelves not thick enough to offer enough =
insulation at the top? =20

5. Finally, my husband thinks that the insulating fiber and gas would be =
a much better idea. I have held back because of environmental and =
health concerns. Probably with go that this summer when the burning =
bans are on. He received a turkey cooker as a gift and is wondering =
about using the burner in a raku kiln. I know the question was asked, =
but nobody was brave enought to say that they had tried it. Somebody =
must have done it. How did it work?

Thanks for your help and some interesting discussions.
Julene, where the river is still wild in Northern Wisconsin

Snail Scott on sat 22 mar 03

At 10:48 AM 3/22/03 -0600, you wrote:
>...firing a woodfired raku kiln...hardbricks...could not get it up to
>Does using the insulating bricks make that much of a difference even at
raku temperatures?... Does one need to use the split wood?...I used the
metal from the dryer...would it act more as a large heat sink? Does
building too solid of a raku kiln give more of a heatsink than added
benefit? ...Are the 5/8" kiln shelves not thick enough to offer enough
insulation at the top?

What works for a 'regular' kiln may not be best for a
raku kiln. Think about how long it took that ^10
woodburner you saw to reach red heat. That would work
for a raku kiln, if you were willing to wait that long!
The speed of a raku kiln (which many of us consider
integral to the spontaneity of the process, but which
isn't essential) relies on having the absolute minimum
of thermal mass. Hardbrick is like a sponge soaking
up heat almost as fast as you fire. Your firebox and
vent may be fine, but with all that brick mass, it'd
be tough to tell. and a waste of wood, too. Thermal
mass is to be avoided for raku. You don't need or want

The metal of the dryer drum will add only negligible
thermal mass. It's those hardbricks that are the real
problem. Yeah, they're much cheaper than softbrick,
but they make you use a lot of fuel (and time) just
heating them up. Your hubby's suggestion of using
fiber is a good one. The amount you'll need is not
that expensive an investment.

Firing with wood should work just fine, though. You
shoudn't need to use gas if you'd rather not. I've
never rakued with wood myself, but I have watched
Pueblo-style firings which used wood and reached
raku temperatures quite quickly. You will be better
off splitting the wood, though. You will get a hotter
firing faster. Just as with a woodstove, kindling
burns fast and hot. It doesn't make for long,
sustained heat, but that's not what you want anyway.
Big pieces of wood will just slow you down and a lot
of the heat will go to waste because of the longer
time it will take to reach temperature.

As for the shelves on top: They won't do much for the
insulation. Instead, the thicker they are, the more
thermal mass they add. But, it may help if you put a
piece of fiber blanket on top during the firing.

You sound like you're not far from success, though.
Good luck!


julene on wed 2 apr 03

We had snow this weekend and so were able to fire up the Raku Kiln after
implementing improvements from advise I was given. My nice Minnesotan
friends came over to give me a hand. They are a bit older than my usual
firing companion and don't need to be bribed with hotdogs and marshmellows,
though good T-bones helped.

The new design looks just like an outdoor barbeque grill. The firing was
great. I do believe we have some new converts. Steve Brafman might be
starting a new revolution here. I did send off my Jack Troy book and some
great pots. Hope I get the book back. I sure it will be read. My husband
had them do the pots in the way he learned from Steven with a salt reduction
at the end. The pots were wonderful.

What we found from this firing:
1. The common bricks worked for the firebox and shell, but the lining of
the chamber should be at least hardbrick. It is very hot in there. The
hardbrick takes a long time to warm up, but hold the heat once you get it up
there. We are going to get soft bricks to line the chamber before the next

2. The thermocouple worked great. We didn't use it in the raku kiln
before, but it showed us how we were doing and what was working and not
working. It didn't really matter if the multimeter showed the temperature,
one could see if the temperature was rising of falling by the mv reading.
The charts were easy to translate.

3 We added a small fan in front of the firebox that really helped keep the
draft going through the kiln. It was just one of those cheap little fans,
but it was quiet, so as to not ruin the experience.

4. We used a combination of sticks, pallet ends and split oak and pine.
Probably too much wood.

Firing the raku was a great learning experience and firing it in a woodkiln
was well worth the effort. Do any of you have recommended glazes for wood
fired raku? Seemed some melted better than others and took the ash better.
For us it worked better to have the pots all at the same level as insides of
the upper bowls did not melt. May have been too much ash. We will need to
work on starting with possible some horsehair pots before rotating in the
glazed pots once it gets up to temperature.

We still will probably build the fiber/gas version for the summer, but this
kiln is a great help to me in learning to fire with wood. I am now thinking
about a lowfire salt kiln.

The electric firing was great, too, but I am still wondering about the
different iron oxides and their affects on the saturated iron glazes. Guess
I will have to try the Spanish red iron oxide and see if it gives me the
results of the first batch with the old oxide.

Lee Love on mon 3 jan 05

Lowfire ain't just for those macho electric kiln firers. ( Yeah,
macho... look at all that uranium waste they are making from the nuclear
electric plants! ;^) )

I put TAK fat white test tiles in my woodfire bisque today (Jim
in Saitama gave me some no-lead frit.). Pulled them at 1600*F (used
two wooden slats like chopsticks. Made a double brick hole for the
pulling) Reduced in sawdust. Looks just like back home. The
copper wash had too much copper. (Yeah, yeah... I only put copper on the
outside.) Need to dig up the old recipes. This is the closest thing
to shino I have been able to find in a low fire glaze. Goes on thick.

Click on next, two photos:

Tak Fat White Raku Glaze
Comments: A Kurt Wild glaze, it came from a student named Takahara.

Fat white, big crackle
Give it time to cool just a second/deep reduction

frit 3134 100
silica 6
epk 10

tin or opax 10 If you want a clear leave this out. Bentonite will
help suspend it.

Takes copper well: blue/green to red/blood .
Variations --
Takes copper well
Leave out tin for clear

Lee in Mashiko, Japan WEB LOG Photos!

in Mashiko, Japan WEB LOG Photos!