There are as many styles of wood fired kilns, as there are potters
to fire them. Many are copies of traditional designs from the East, some are hybrids,
which potters have developed to suit their needs, some result from a potters aesthetic
choice and others are dictated by local conditions. A local condition in our part of the
world is the winter frost that may penetrate the ground to a depth of 3 feet, making the
need for footings under a kiln a serious consideration.
A chance design element resulted from our using a cement-floating
slab, instead of a stepped hillside foundation when building a Noborigama. Our pottery is
located on a former dairy farm. Twenty-five years ago we poured a cement slab for our hog
pen, to keep them out of the mud pit their rooting created.
In 1990 we chose to build a wood kiln on the existing floating slab
that we no longer used for the pigs. This was under the pretext that it was cheaper
(already existing) and easier than digging a new foundation.
The incline for the chambers was accomplished by using cement blocks
to build the 13-inch step up for each of the two chambers. The result is that the floor of
the second chamber is 73" above the ground (floating slab). The stoke holes for the
chambers are 47" and 60" height respectively. At first this design might seem
awkward, since it necessitates building a platform in front of the chambers for loading
access. However, the unexpected bonus of the design comes from the ease of stoking in an
upright position and physically being below the heat.
I have visited over 50 wood fired kilns around the world and each
has a unique quality and personality. The one factor common to many climbing kilns,
especially the Noborigama, is that by being built into a hillside the fire boxes in the
upper chambers are often knee high or even at ground level. This means the stoker is
standing in front of the hot kiln with their upper body above the feed port, resulting in
a cooked stoker with a face full of smoke and a sore back.
Having the chambers above ground level (the result of the floating
slab) means the stoker stands upright and is below the smoke and heat. It also means that
the stoker is in a good position to see what he is doing when feeding the step-down
fireboxes (they are almost at eye level). The platform that was built for loading the
upper chambers serves as a convenient way station for the wood when stoking.
I make no claim at inventing anything new and wonderful, in fact
last year I saw a similar foundation design at another pottery. The design in our
situation was just the by-product of an existing building site (foundation), however,
standing upright and being below the heat and smoke has added a level of comfort that I
have grown to appreciate when spending the extended hours at a wood firing.
As I finalize plans for another wood fired kiln at our pottery I
will make allowances for a tortured back. Our next kiln will be built with an inside
chamber height that allows one to stand upright while loading. And the fireboxes will not
require the potter to kneel or bend for endless hours while stoking. While the design of
the raised firebox/floor of our first Noborigama was a fluke, it will be a planned element
in our next kiln.
