 |
Beginning
the kiln--the frame
It took
me awhile to find someone to agree to weld the frame together for me. I
was willing to hire someone, but not sure where to look for
a reliable welder. A friend of a friend decided that he would supply his
expertise and do the welding for me, if I directed, because he knew nothing
about kilns. I invited him over to see the kiln that my potter friend had
built, to give him an idea of the scope of the job. Then, after detailed
discussion of the frame construction, I searched out and found a supplier
for the steel tubing and angle iron I needed. What an interesting sight
to see giant wet-saws cutting 20 foot pieces of 3 inch tube
in half like they were butter. After getting the steel, I rented a "chop saw" and
a generator powered welder and my welder friend came out for the day. He
taught me how to use the chop saw properly and then grind the sharp edges
off the cut steel with a hand grinder.
TOP
|
  |
Then I would put
the frame pieces together and tell him where to weld. Another friend of
mine volunteered to be a third hand the two days we spent welding, and her
help was invaluable. I started the frame by building three cross-layers,
the bottom, the layer that holds the brick and the top, and then we attached
uprights to put it together.
TOP |
“Cyndi
volunteered to be a third hand the two days we spent welding, and her
help was invaluable.” |
 |
| The cart was
then built, upside-down, and set up on unattached tracks to attach the door
frame and test it out. |
The next thing I focused on
was the burner system. This welding job was pretty special, it needed to
be sealed totally for the gas line. I called my gas company (propane) and
they directed me to someone who could fabricate what I wanted to build.
TOP |
 |
| I took the parts out, laid
it out for the guy and two days later he had built it and
air tested it for me. I bought the actual burners themselves by mail from
a source in Los Angeles. Then, the propane guy came out, scoped out the
job and came back and connected the venturis to the system. |
 |
At this point I also ordered
sheets of galvanized steel for the outer surface of the kiln. It serves
both functionally-holding the thermal insulation and bricks in and visually,
being much more attractive to look at than the outer layer of the kilnwall,
which is rigid thermal insulation. When that was ready, I hired a welder
from the want ads, to come and fix a few minor adjustments and put the galvanized
steel into the frame. Unfortunately, the film was defective from this point
'til after the kiln walls and chimney are bricked.
TOP |
 |
 |
Bricking
The first
thing I did, to start filling in this blank frame I had constructed, was
to line the sides and bottom layers with thermal insulation. This kiln design
has six burners coming up from the bottom along both sides. I had to cut
the port holes for the burners in the insulation. It was then I realized
that I had miscalculated and made the burner assembly 5.5" too wide, necessitating
a crosspipe being shortened. Lining the kiln was easy, as the insulation
material is much like layered cardboard and very easy to cut to fit. The
only drawback about working with the insulation is the itchy dust. When
the insulation layer was all in, we started on the walls. The side walls
went fairly quickly and smoothly but the back wall, with the flue, chimney
and damper to think about went a bit more roughly. I was unhappy with the
back wall after the first try. After discussing my design with an online
friend, in particular the meeting of the cart and the kiln at the back wall,
I decided to take the back wall down and rebuild it, changing the cart/kiln
seal and fixing the crookedness that bothered me. The second incarnation
of the back wall was much better. My flue design is Nils Lou's venturi design
from The Art of Firing, with a horizontal damper up above the flue.
TOP |
 |
| Next I had to build my arch.
This was a challenge. I wrangled Gary to help me build an arch form out
of plywood, cutting arcs of wood and running strips lengthwise. I used Fred
Olsen's book to determine how many bricks I should need. I decided to cut
the sideskews for the arch, as I had forgotten to order them with my other
brick. |
 |
| “Rusty
Wiltjer's suggestion to load the cart with hardbrick on top to hold the
softbrick in place...was brilliant!” |
I was confused, at first, as
to how to determine the skew brick shape, but after some discussion of the
process with friends I bought a mitering square and laid the archbrick out
marking the skew angle on paper, which I used as a guide to set the mitering
square used to mark each skew brick.
TOP |
 |
The Cart
The cart was a bigger job. I consulted in
detail with my friend Rusty Wiltjer on this part,
and his suggestion to load the cart with hardbrick on top to hold the
softbrick in place while you "sand it down" to fit was brilliant! It worked
like a charm, with a layer of hardbrick between the thermal insulation
and softbrick to give the softbrick a sturdier base. I had to have Richard,
the welder, redo parts on the cart when I realized what I needed finally.
I think I bricked the cart a total of three times before it worked smoothly.
It took some correcting of the top layer of bricks on the cart, so it
would fit as it rolled into the existing kiln properly without catching
and pulling bricks off on its way in or out. Once I had it so it fit,
I ran the cart in and out several times to smooth and sand the seal. Richard
showed up in the midst of all this and finished the door pulls, latches
and some other final pieces.
TOP |
  |
Now I was ready to FIRE,
I thought. I realized after I loaded up the first bisque load that I hadn't
put the pyrometer in. I used cones and although it fired quite unevenly
(06 flat on top barely down on bottom), I was pleased with the speed of
firing and how easily I seemed to get a feel for the burner adjustments.
I pretty much left the damper alone for the first few firings. I decided
to test my cone 6 oxidation glazes to see what they would do in a gas kiln.
I got some wonderful results in the first two firings, even though I overfired
them to cone 8 on the top with cone 6 at the bottom. Meanwhile, I discussed
the kiln with my buddies online and they gave me some ideas for some "tweaking"
to do on it. I decided to make a couple changes, eventually, but will be
firing it, meanwhile.
I will continue to document this process with photos, and eventually finish
up this ongoing page with some beautiful glazed loads!
TOP |
