Sunday, July 10, 2011

Chop Wood, Fire Pottery

It's an apparently simple process: chop wood, boil water, make tea. Tea bowls also appear simple, but we learned recently their simplicity belies their making.

We met pottery artist Thomas Fossier a couple years ago at an arts and crafts fair, and were quite taken by his tea bowls. We struck up a conversation, shared anecdotes about travel in Japan and invited him to learn about Tea with us. One of our friends bought a bowl from him at that craft fair, and several of us went in together on a bowl to give to our Sensei in Japan when we visited her last spring.

Thomas brought several tea bowls to our May Tea Ceremony demonstration fresh from a firing at a friend's kiln in Oregon. The bowls were lovely, and it was wonderful to be able to share tea with the artist and his creation. Thomas told us he was building a kiln of his own, and invited us to come see it when it was finished. The type of kiln he was building is anagama, the traditional wood-fired kiln of Japan. (Wikipedia has a much better explanation than I could write, http://en.wikipedia.org/wiki/Anagama_kiln.) Typical anagama kilns have a single chamber; Thomas designed his with two chambers, the upper chamber at a right angle to the lower chamber. Stoking the fire is done primarily through the lower chamber.

Thomas Fossier's kiln
Last weekend we got a message that he was firing up his kiln. He began firing early on a Friday morning. When we arrived around 6:00 that evening the kiln was glowing merrily.


Pots can be seen glowing inside the kiln
as wood is added "shotgun style" to the firebox.
We thought it looked merry, but that wasn't necessarily the case. Thomas had been struggling with the kiln all day. He explained that when he began firing that morning, the weather was cool and overcast, even a little foggy, and the kiln temperatures climbed as expected each time he stoked the firebox. But kiln temperatures plateaued as the day warmed, skies cleared and the fog burned off. It seemed that no matter what variety or how much wood was fed into the firebox temperatures hovered, climbing or dropping by a few degrees, but not even approaching the 1400°C that was needed to fire the pottery and create the surface glazing and textures he desired.

The reason? Thomas theorized that it might have been high barometric pressure, or "thick air" as he characterized it, kept the kiln from drawing in air and starved the fire of oxygen. Regardless, in the two hours we spent with him the kiln's temperature hovered around 750°C, never making the dramatic leaps of temperature he anticipated with each stoking.

Thomas and his friend Scott, also a pottery artist,
stoke the firebox with scrap wood from local
musical instrument makers.
Scott and Thomas' wife Suzanne watch
for smoke from the chimney -- a sign
that the kiln is drawing properly.
Thermometers register cool temperatures from
rear (top thermometer) and front chambers


The next morning we received an email that Thomas ended his firing at 7:00 that morning, "having gotten just above red heat throughout the kiln and too exhausted to go any farther." He never really figured out the problem but chalked it up to the learning curve. What will he do with the half-fired pottery? Most likely he'll close up the kiln, cover up the firewood and wait till autumn and cooler weather.

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