Friday, October 17, 2008

Smoke and Mirrors

There was surprisingly little smoke (and no mirror).

Helped a friend do the inaugural firing of her wood kiln last Sunday. It was fun. She had spent three hours stacking and restacking the ware before I showed up. We spent another hour assembling the lid and putting the chimney extension up through the roof of the shed. The firing itself took about 7.5 hours. I stoked and kept the logbook for about half that time. In exchange for my help, she made room for a couple of my pots.

She is a meticulous potter, and that characteristic extends to her kiln building and firing. She had planned every detail and the firing went off almost exactly as she had laid it out. The only problem was that the damper mechanism jammed up about halfway through. The mechanism involved two small rectangular pieces of kiln shelf (silicone carbide, I think) sliding through vertical openings on either side of the chimney as it came out of the back of the kiln. She had made the shelf pieces fit too well into the slots – they swelled in the heat and got stuck, so we couldn’t adjust them. Because the kiln is made of soft refractory brick, we used a length of thin metal, like a putty knife, to make the slots just a little wider. Worked fine from then on. She was very disappointed at this design problem that she felt she should have anticipated. But the whole thing – from the clever way the removable top section of the chimney stack was designed, to the simple but effective method for keeping that stack from wobbling in the stiff wind, to the extremely precise use of a secondary atmospheric damper – was so well executed, the temporary damper problem seemed to me a minor (and easily fixed) setback.

I have long wanted to build a small gas-fired kiln for my own work and this experience helped me see how challenging that will be!

My pieces turned out poorly, but that had nothing to do with the kiln or the firing. I had grabbed them off a shelf of pots that were in the not-very-good-but-worth-using-in-a-test-someday category. If there is a next time, I'll be prepared with better stock.

1 comment:

PAT Fuller said...

What happened to the picture of your "pot"? Sounds like a very labor intensive operation to fire up a new kiln.