Slightly Off Center

We planned to unload the glaze kiln Wednesday night, so we could both attend our book arts meeting Thursday afternoon. Which meant I was down at the studio at 7 am to start the kiln cooling. Cracked the damper, opened up the burner ports, pulled the ceramic fiber strips off the door jambs (as best I could reach. Tea had every folding table and flat surface in the kiln room covered with stacks of bowls for his next firing). Took a pic from my phone camera through the top peep. That's the edge of a pie plate, glaze is mature and well-reduced. Promising... except I think this is one of the ones I glazed after I mixed up the new batch.

I literally phoned in the rest of the cooling, asking Tea to pull out the damper further, getting Jon to crack the door. Got there a 7 pm, just as he was preparing to leave, and got him to help me pull out the car.

Which was beautiful. Everything turned out fine, minimum of oxidation, only one soup bowl with a cracked rim and a baker with bubbled black stain. Whatever was wonky about the ball clay doesn't seem to have affected the glaze at all, so I'm fully stocked again, and can start preparing for Clay Fest.

Last week's glaze fire came out beautifully, the second in a row with even heat at top and bottom, as well as very little oxidation. The thing both had in common was a full layer of four inch shelves, loaded with bowls, across the bottom of the car (I usually split the bottom layer, have higher items at the door, lower in back). Think I'll have to continue this practice, at least for another firing; I have twenty Empty Bowls that didn't fit into this kiln.

Last firing, the top ended up slightly hotter, by about half a cone. This time? The cones dropped in perfect unison, all the way from cone 4 to cone 10. Definitely saving these cone packs. Maybe I'll have them framed...

Got some beautiful results, including the special order white cat teapot and the blue heron pitcher. The kestrel large serving bowl is just for me. Think I'll take it down to my sale in Roseburg, end of June.

What a beautiful firing!

When I finished loading my last glaze firing, I had so many pots left over, and still felt a little under-stocked for my upcoming show. Jon, another Club Mud potter, suggested I do another firing with a four-shelf footprint; he does it all the time when he hasn't got enough for a full load. I did some calculation, and decided I had enough work to make it go, so the day after our coast trip, I was back in the studio loading the kiln.

Loading goes much faster with only four shelves. I laid them right down the middle of the car, and could reach to set all the shelves from one side, likewise the pots (no more squeezing between the table and the door to get to the back side). With only two-thirds as many pots, the loading also went faster; I started around 8 am, was done by noon. Fit every one of my leftover pieces in, even dusted off a few demo vases from pre-pandemic Art and the Vineyard and glazed them up. Because I assumed the firing would also be faster, I started the pre-heat at 9 pm rather than my usual 8-8:30. As it turned out, I coulda waited until 10; cone 08 was down one the bottom the next morning at 5 am, cone 04 on top. I adjusted the gas and air from warm-up to full and slammed in the damper for a later body reduction, hoped for the best.

Firing day was much easier than usual, because I'd not done any glazing, so didn't have glaze room and floor cleaning. I did mix up a couple of batches of glaze, but most of that had already been done the previous week as well. So I spent much of my morning on the wheel, throwing incense dragons, getting a head start on my next production cycle.

The firing went smoothly, but fast. Cone 8 was down by 1 pm, cone 10 by 3. I soaked it an extra 15 minutes to help the bottom catch up, but shut everything down by 3:15. Shut off the burners, closed the ports, bled off the gas line and shut it down. Recorded the gas usage--55 units, about nine less than last fire.

Forgot to close the damper.

Which I only discovered the next morning, when I came down to box up my dragons to take home. The kiln was already down to under 700° F, way cooler than normal. I slammed the damper closed, praying that I hadn't broken all my pots by cooling too fast.

The suspense lasted until Sunday morning, because Saturday is Market day, and I'm far too tired afterward to even consider going down to the studio. We pulled open the kiln... and it was beautiful. Shiny, creamy pots, just enough iron speckle, lovely colors. Temperature difference between top and bottom less than half a cone. The usual amount of oxidation, but no over-reduction on the top.

The only breakage from the speed cooling was in a couple of Jon's pots, refires with glaze touch-ups. One was a mug he'd ground free of glaze drips, that ran again and stuck to the shelf, then cracked in cooling. The other a very thin bowl that just cracked from rim to base, either from speed cooling, or possibly heating--it was right at the top, which heats up fastest.

Jon says his pots are a little shinier than usual, probably from the cooling (crystal formation takes a slow cool-down). If that's the case, I may do a short speed cool after my next firing--but not all night--to see if it can help control the brown, matte surfaces I can get at the very top of the kiln.

In any case, here are pictures. And I finally feel like I've got proper back stock again.

...although more than half of the kilnload--not shown here--was commissions and wholesale orders. This is just the bit I get to take home for Market.

Still a lot of oxidation in unexpected places, including top and back of the kiln, with good reduction near the door--that never happens. Part of the problem may have been my fault. I didn't notice that the potter who fired previous to me had recut a brick that sits atop the damper filling the gap between it--an old kiln shelf--and the chimney. We measure how far open or closed the damper is by marks on the kiln shelf that we line up with that brick, and since the new one was bigger than the old, my body reduction setting was a good inch wider open than ideal. I caught the mistake an hour later, trimmed down the brick so the damper read accurately again, but at that point, the damage was done.

The biggest negative effect was on the dinner setting. Some of the pieces got good reduction, some didn't, and the iron oxide stain in particular got bleached out. I'll have to talk to the buyers next week and see what they think. I may need to redo a bunch of plates. Fortunately, I've got a back-up set of the small bowls that didn't fit into this firing, so they're ready for next time.

That said, there was still a lot of nice stuff coming out.

So the kiln never did make temperature; stalled at just past cone 9. I finally shut it down at 10:30 pm. Came back Friday night to unload, to discover a kiln full of brick-red matte-surfaced pots. Something was wrong with the glaze.

I don't know if something was mislabeled in the materials room, or if I just screwed up mixing it, back in October, but every pot I made in the mad scramble following Clayfolk is unsaleable. Cookie jars, teapots, pitchers, bowls, mugs. I could cry. I did cry.

About a third of the kiln was still usable, work held over from the last fire, or glazed from the previous batch of glaze, before I mixed in the new stock. Some of the pieces glazed with a mix of the two seem to benefit from refiring in the electric kiln, so I'm trying to do more of that.

Meanwhile, I've washed off all the leftover pots, left them in a warm kiln room to dry. I'm making more dinner and dessert plates, stew mugs, tall mugs, painted mugs. I'd love to have cookie jars and teapots, but there's no way to get them dry enough to bisque in a couple of days. Because I'm trying to push out another firing, a four-shelf stack instead of the usual six, next week, in time for the last two weekends of Holiday Market. I made up new glaze during the firing, and have tested it in the electric kiln. It seems to be shiny, as it ought to be.

Wish me luck.