Firing Day

Firing days are hard.

To begin with, they're long. I fire a 50 cubic-foot kiln, and even if I candle (preheat on a low flame) overnight, I'm still looking at 12 to 14 hours of firing to go when I stumble in at 6 am. And because the kiln is located at a pottery co-op a good 20-minute drive from home, once I'm down here, I'm here for the duration.

In theory, this is a perfect time to work. Twelve uninterrupted hours in the studio! In practice, it doesn't generally work out that way.

To begin with there's the kiln itself, demanding attention. There's burner and damper adjustments at the start, turning up gas and air and draft, watching for the first cones to drop so I can get the body reduction done. If I'm lucky, cone 08 will be nearly down when I arrive (If I'm unlucky, it will already be down and I'll have to slam the damper in and hope for the best). More often, I've been too timid in setting the burners trying to avoid the latter problem, so I have to check the peepholes every 30 minutes or so, until the cones bend over and I can put the kiln in a reducing atmosphere for half an hour.

Afterward, there are more adjustments. Reset the damper for neutral-to-reducing atmosphere, tap the burners up a little bit, wait, look for flame flickering in the chimney, tap down, look for less flame in the chimney. Rinse, repeat.

Eventually, the beast will be set to fire a while on its own, and I'll conquer the urge to keep poking at it and try to get something done. It's still tough, though.

To begin with, I've usually just come off a marathon of throwing pots, trimming pots, glazing pots. My brain wants to be doing something else, for a while, not more of the same. I've tried throwing bowls for the Empty Bowls sale, but then I have to get them home to trim before they dry out. I've occasionally worked on sculpture, if I have an idea to attack, and two or three more days to follow through and finish it. Masks are a good project: small, portable, and I can usually do two or three before my body reminds me that I've been up since oh-god-early and can't I stop being productive for a bit?

So what works? Cleaning, actually. Clearing up my mess in the glazing room, rinsing my brushes and mopping the floor. Writing, sometimes--I've written Christmas letters, and done a lot of updates on my website from here at Club Mud, using the Art Center's wifi. Graphics projects. I designed the new Clay Fest postcard before lunch today, and should really have another look at the early drafts of the poster.

But mostly, I veg. I read a novel (or two). I dig up old comics from the newspaper bin, do sudoku and cryptoquotes and crosswords. If I brought a laptop, I'll surf the internet. (If I didn't, I'll try to with my phone.) I snack way too much. Between cones 1 and 4, when the firing's at its slowest, I'll go for a long walk. I've mapped every alley in this neighborhood, and I'm starting on the bike paths.

I envy my fellow potters. Jon frequently fires through the night, napping out on the table between adjustments. Tea is notorious for setting the burners and damper and going to see a movie. (Notorious for the time the kiln fired fast and he hit cone 12 by the time the credits ended.) Me, I fidget too much to let go like that.

In fact, I think I'd better check the kiln now. Cone 8 should start bending any time.

How Meta is That?

Writing about what I do while firing the kiln, while firing the kiln.

Technical Jiggery-Pokery

If I'm gonna throw technical terms around, I should probably define a few of them. Consider this your reference section.

Temperature. Degrees Fahrenheit, or Celsius. Temperature of the thermometer or thermocouple persuasion isn't that useful in determining the progress of your firing. Clay and glazes melt as a function of time and temperature. If you raise the temperature of the kiln slowly, your pots will mature at a lower temperature than if you fire fast.

Cones. Pyrometric cones are formulated from a mixture of clay and glaze minerals to melt at a specific temperature given a measured rate of firing. Or, simply put, they melt the same way your pots do, so by watching them in the peephole, you can tell how close to finished you are.

Cone 08, cone 8, cone 10. Different heat points in the firing. Cones with a zero in the number (read "cone oh-eight") are negative numbers, so cone 08 is 15 cones cooler than cone 8 (because there's no cone 0. Go figure). Cone 08 is when I do body reduction, cone 10 is when I shut off the kiln.

Reduction. In a fuel burning kiln--gas, oil, wood--the amount of oxygen in the kiln can be adjusted to get clay and glaze color effects. Most commonly, by reducing the amount air in the kiln at critical points, you can make iron spots appear in the clay, and make iron glazes green or blue, copper glazes red. This is called a reducing atmosphere, or reduction.

Body reduction. Reducing atmosphere at an early stage of the firing, before the glaze seals over. This allows you to reduce iron in the clay itself, which comes to the surface in the iron spots that freckle the surface of most stoneware clays.

Oxidation. The opposite of reduction. Makes my glazes white and unattractive, so I try to avoid this. I'm not always successful, because old kiln haz air leaks.

Damper. The kiln shelf that slides in and out of the chimney to control the amount of air drawn into the kiln (draft). Closing the damper creates reduction.