WOODFIRING AN ANAGAMA
Firing an anagama, or Japanese style kiln (roughly translated
means cave kiln) is challenging work. There is no science to
support exacting results, only hypotheses and techniques
specific to each kiln. Typically an anagama is built up a
slope to help draw the flame from the main source of heat up
through the chimney. Variations of tubular and bottle shaped
kilns, or separate chambers (naborigama) will create
different variables and results. The
Jewel Creek anagama is 18 feet long
with a twenty foot stack. It looks like a giant bottle
on its side with a four foot arched door at the front
that is bricked up with thick refractory bricks and the
door on its iron hinges. There are three ranks of
shelves with stoke alleys in between. Above the gap are
the side stoke holes for smaller wood. It can contain up
to 500 pots and sculptures at a time. The firebox is
just behind the door and is seven square feet. We fire
predominantly with Douglas Fir and alder from the
surrounding area. The ash from these woods give the pots
a distinctive color endemic to the Northwest. A single
firing requires five cords of wood. The process starts
out as a little campfire and becomes a raging inferno
withing two days and temperatures that exceed 2400F.
Words cannnot describe the beauty of the fire and the
pots glowing and shining inside as the flames thread
their way through the kiln and reach for the air from
the top of the chimney.
The loading of the kiln is an all day event. Most woodfire
kilns take two days to load. At least seven people or more
fire the Jewel Creek kiln together. We take shifts firing,
cooking for each other, and sleeping. Three people must stay
up all night to tend to the fire. The point is to push the
temperature up steadily over many hours while attempting to
get the back of the kiln hot. A normal firing is around
ninety to over 100 hours. Porcelain and stoneware are the
types of clay that can endure the heat. The pots have little
balls of clay and seashells, which are refractory, glued to
the part that will rest on the shelf so that the accumulating
ash does not melt and adhere. Crystals bloom within the
melting ash and freeze in time when the atmosphere becomes
cool enough. Terms like "flashing," "blushing," and "carbon
trap" are used to describe the variations on the clay's
surface. There is easily a ten percent loss of pieces, often
much more. Clays crack, pots move and stick to, or "kiss" one
another. Refiring pieces is a way to salvage a dry,
lacklustre surface in hopes of achieving more interesting
results.
Some firings utilize a technique called reduction cooling
where small amounts of wood are periodically fed to the
smoldering coals. The ash deposits can become unassimilated,
or unmelted to the surface of pots, creating a rough, crusty
finish that some potters find appealing. The day of unloading
is at least four days after the last piece of wood is burned.
Sometimes even then the floor of the kiln is still so warm it
may melt the bottoms of shoes. As one can imagine this day is
very exciting. Once in a while, however, the results are less
than stellar. There are times when only a few pots out of
hundreds are acceptable. In spite of this crapshoot, we
potters only want to do it again, for it is the process, the
sense of community, and the quest for those amazing gems that
keeps us coming back for more.