Rebekah Shope on tue 30 jul 96
Hi everybody,
Several people have expressed interest in hearing about the raku kilns
that we built this summer out of 55 gallon drums.
I am a student at Indiana University Southeast, and we had a class
this summer on low fire ceramics and raku. There were a lot of people
in the class who built kilns according to some ideas that our
professor had collected. We took a 55-gallon drum and cut off the
bottom section of it. You could also use expanded steel or wire. The
drums are stronger and last longer before being worn beyond use, but
the wire ones are definitely lighter.
Be sure that you know what material was in the drum before you cut it
with a torch. If it was flamable material and some remains, it could
explode! We had measured the height of our raku kiln according to the
width of the ceramic fiber material that we were going to use. I think
the measurement came out to be about 24 inches high which was right at
2/3 of the barrel. We bought ceramic fiber material from Louisville
Fire Brick Works, a local wholesaler of firebricks and other
refractory materials. We also got some stainless steel pins and clips
that are made especially for use with this material. They also make
an adhesive, kinda like mortar that is refractory also. There is
also a liquid that you spray on the fiber when you have it together
that is made to stiffen the ceramic fiber for durability. You should
think about how you will lift it off of your kiln base. If you want
some kind of pulley system, you need to think of how to do it, and how
it will attach to the drum. The book by Steve Branfman is a good one
for seeing pictures of this.
If you are putting handles on and you must put screws through the
drum, you need to do this before you line it with the ceramic
material. You also need to cut a peephole and chimney and drill holes
for the pins before lining it. We cut out a circle from the fiber
material to fit the inside top of the kiln and a length of the
material that will go all the way around the inside of the drum and
overlap probably at least 4 inches or so. When you have done all of
this, put the circular piece of material inside the kiln and then the
piece for the sides... put the pins through the holes and the locking
clips on. We had to bend and cut the pins so that they would be the
right length to lock on. You will understand when you see the pins.
We put extra pins along the seam in the fiber.
We then made patches out of extra fiber material to protect the
stainless pins that are exposed on the inside. To adhere them, we
used that mortar-like adhesive spread on like peanut butter on bread.
There was a little fiber that stuck out past the edge of the barrel
that we had intended to fold down over the edge to protect the rim of
the drum from the heat. We cut slits in it so that it would bend over
the edge, and then cut out more fiber material to cover the edge of
the barrel. These pieces came over from inside the drum to the
outside and were adhered to the fiber on the inside. Where they
extended to the outside, we wrapped wire around it with a small spring
to keep it snug. I just used two coathangers... the length of the two
were the perfect size... and bought a spring from the hardware store.
There is a time period that the adhesive has to dry before firing... I
think its 24 hours. After you get the kiln assembled, and have cut
out the fiber where the peephole and chimney are, sticking a little
adhesive inbetween the fiber and the drum with your fingers, You can
apply the hardener to the fiber material. But dont apply the hardener
to the part that will be in contact with the brick base, because the
hardener tends to make it chip off in chunks when handled. For the
brick base, we used some soft firebrick, called IFBs or insulating
firebrick. I leveled off a place in my backyard to place them on. We
got some large firebrick tiles that were seconds when the firebrick
company made them for a shuttle kiln, and these made a good base...
they were broader than regular bricks and had channels through them.
But you can use concrete blocks to put your first layer of bricks on.
This just means that you have to be sure that you have a sufficient
layer of softbricks to protect the concrete from the heat, because
concrete explodes when it is heated beyond 400 some-odd degrees.
Also, the soft firebricks dissolve when exposed to rain and weather,
so you will have to make sure they dont get wet... you can get a
waterproof tarp to put over the kiln. (I bought one, and the water
went through it!!)
We also made burners for our kilns. We made what are called Alfred
Burners. They were designed out of pipe fittings by graduate students
at Alfred University years ago. They have no safety devices on
them... unless you buy them and put them on, but they work well. It
may be a bit of an overkill for this kind of a kiln, but in the
future if you build a larger kiln and want to use atmospheric burners,
you can make some more of these. The worst part is finding the right
orifice size for the pressure that is coming through. Using propane
gas, and a regulator that regulates at 11" of water column, depending
on how hot you want to fire it, here is a chart for the orifice size:
at 11" water column:
size of orifice BTU/hour
7/64" 84,000
1/8" 110,000
9/64" 138,000
5/32" 158,000
11/64" 200,000
3/16" 240,000
A friend of mine gave me these #'s. He got them out of a book on
building your own pottery equipment. I dont remember who the author
is, or what the exact name of the book is. This kiln cost us a little
over $100. We did get good prices on materials though, because we
bought them as a group. Im sure if you shop around for materials, you
can build one for less than $150.00. Happy raku-ing
Becky Shope
Jeffersonville, IN
Bob Pulley on tue 30 jul 96
I've probably mentioned this before, but with the current discussion about
raku, I'll repeat myself. We used to build raku kilns very similar to the
barrel kilns, but a lot lighter and more simply. We began with a garbage
can lid ( it already has a handle). Walls were made of 2"x4" hardware
cloth wired in a suitable cylinder and wired to the lid (bigger than the
lid). Spun Kaolin insulation was wired in with kanthal wire. I would buy
toaster replacement coils from the hardware store and straighten them. Cut
holes near the top for draft and a hole at the bottom for heat and you can
lift the kiln off the pots with one hand, no pulleys or helpers necesary.
Bob Pulley
pulley@mail.cpbx.net
Robert Pulley
pulley@mail.cpbx.net
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