COLUMBIA

Potter's
Barbecue

Exploring gas firing on
a smaller scale
By Don Jung

I love a barbecue! Can't wait to fire up the propane
burners and do some grilling. If only it could be that easy
to fire up some pots, too.

Well why not?

There's a certain mystery about fuel-fired kilns,
especially in reduction. When there are flames involved,
there does seem to be a heightened element of danger
and excitement, but with education,
training and familiarity, I've found
that a fuel-fired kiln doesn’t have to
be any more intimidating than your
backyard barbeque. It can be safe,
simple and even faster. I believe the
rewards are worth the effort. I must
admit, when I started I thought fuel-
fired kilns were large, laborious, heavy,
smoky, fire-belching and complicated.
I remember the line from the movie
Apocalypse Now: “I love the smell
of napalm in the morning,” and I
associated that with a fuel-fired kiln
for a while, especially after loading
and stoking the Tozan Naborigama
kiln in Nanaimo.

One of the reasons electric kilns
are so popular is the ease with which they can be used.
‘They are fairly clean, simple and reliable. They also don’t
take up that much space. So could I get that with a gas
firing...something not too big and easy to fire? Well, I did
find something—not perfect, but it’s pretty close. Meet
the Modified Oregon Flattop.

‘The basis of the kiln design can be found in Nils Lou’s The
Art of Firing. It’s a scaled-down version of the Minnesota
Flattop which has been built at the University of Oregon.
Ive simply adapted it to suit my purposes. It’s simple,
reliable and doesn’t take up that much space. It can fire
in oxidation as well as reduction and go to cone 10 in less
than five hours. I believe this kiln fires well because there’s
adequate draft from the double venturi chimney design.
Nils Lou makes a compelling argument for the use of the
venturi principles to get adequate draw up the chimney. If
you have a fuel-fired kiln and have problems with stalling

Potters Guild of BC Newsletter - May 2008

or firing speed, you should look into incorporating the
double venturi into your chimney.

Back to the kiln. P’ve built it on a platform with castor
wheels so I can move it around on my cement patio and
store it in the shed when not in use. I’ve also changed the
chimney so that it’s not right against the kiln but is instead
a couple of inches away and detached from the kiln. The
heavier brick roof was also replaced with a lighter ceramic
fibre one. It’s a top loading configuration and I was always
concerned about brick dust coming down when the roof
was put in place. With the ceramic fibre roof, it’s much
easier to remove and doesn’t crumble during the process.

The kiln is essentially a square box with two ports for
the burners and an exit flue for the chimney. It’s small
enough to be top loading but I could see it being a car kiln

Don's kiln with the original brick roof.

(where the shelves are stacked on an interior moving base)
to make it easier on the back. ‘The cost for building a kiln
like this (without burners, gas lines, gauges and tanks)
is about $1,200, which is mostly the cost of 300 K23
bricks. If you can source some cheap softbricks, you've
got it good. The total (with burners and all) bumps it
up to about $1,600. This is with a set of build-your-own
pipe burners to keep the costs down. You could purchase
them from Greenbarn or Ward Burners but that will add
to the cost. Building your own burners is another article
in itself...look for it in an upcoming issue.

For the gas, I gang three ordinary 20 lb. propane tanks
together and have a fourth one just in case. A normal
firing in the summer uses two full 20 Ib. tanks. In the
winter, itll take nearly three tanks as tank freeze-up
happens much quicker.

Continued on Page 5 Small Gas Kiln