Mark Hewitt Pottery > Mark's articles > the 100th Firing

The Actual 100th Firing

March 31, April, 1, 2, and 3, 2019

Sometimes I sleep well the night of the firing, other times not. Regardless, the alarm went of at four, and soon thereafter I took the walk out to the kiln. Hmmm, it was quiet. Stillman is usually scampering around the kiln, side stoking for early reduction, while Leavitt, his elder brother, calmly drives the train. But the temperature was stuck at 1900F. It’s usually 2300F or higher. Holy shit! This was the 100th firing and it wasn’t going well. Coffee panic set in, we were doomed, the pots would suck (or worse), and the opening would be a total embarrassment. All would be lost.

What had happened? Righteous efforts to reduce the kiln by closing the damper and minimizing the air intake had left the kiln gasping, and frost on the tin roof prevented Stillman from clambering up to pull the damper open a couple of inches. We were hours behind. I put an extension ladder up to the peak of the roof, and, reaching precariously forward, used a strip of wood to push the damper a few inches back across the chimney. We all began the breath.

Slowly the temperature climbed. Finding the right mix of fuel, air, and timing is key. We’re often impatient, stoking too much too quickly, and the kiln stalls. At certain temperatures, however, you want slow, smoky stokes, so the fuel, looking for air, extracts oxygen molecules from the clay and glaze materials, setting up chemical changes that alter the color of both clay and glaze. For instance, Fe2O3 becomes FeO. Too much oxygen throughout a firing produces insipid tonalities – the pots are oxidized. Too much smoke and too little air can cause carbon coring, bloating, shattering, and the other nightmares, especially of the kiln gets too hot at the end of the firing. Just the right amount of reduction, at just the right time, is what we’re after. Goldilocks again.

The shifts change at six, Hamish and my nephew, Luke Wheeler, arrive. Stillman and Leavitt bid a nervous and weary farewell, heading off for the sleep of the dead, and, and the new blood settled in to the task at hand. Luke is an operations manager at a massive warehouse in Louisville, KY, which distributes motorcycle components and accessories. His work is to pay attention to process. By comparison, a kiln is simple.
Together we worked the sides, while Hamish steadily handled the main firebox. We set up a rhythm, watching the pyrometric cones in each chamber to check when 010 falls, 1650F, at which point we begin to stoke in that chamber in order to generate good body reduction. We stoke the front, and immediately stoke the chamber we’re reducing. Then stoke the preceding chambers, let it rest, breath, and wait for the temperature to rise. When it peaks, do it again. One step forward, half a step back. Occasionally forgo the side stoking and bump the temperature up at the front for a couple of cycles. We’re getting there slowly and deliberately, but we’re still hours behind.

New apprentice, Will Baskin, arrived, and began helping move wood, providing backup as needed. Then came veteran stoker, Terry Childress, who’s been responsible for more good firings in this area than anyone, always calmly steadying the ship. A while later David Sutton pulled up. He owns a hair salon and wine store on Franklin Street in Chapel Hill, is a longtime NC pottery fan, and was the high bidder at last year’s North Carolina Pottery Center’s auction for the experience of help at the 100th firing. Last, but not least, my former apprentice, Daniel Johnston, arrived. Having an old hand, someone who has a similar kiln, someone I trust, was vital. I love my crew, but there’s no alternative to experience, and although I haven’t worked alongside Daniel for twenty years, I knew we could work together. We always have.

A big kiln is like a huge double base that requires a team to play. Getting the right mix of players for a performance is key. I’m the conductor, but if the players are green, or reckless, or if shit happens, as they say, it’s good to have a first violin, not a bunch of inexperienced second fiddles.

Carol, who always does a shift the second night, bumping the gas pokers up while I get some sleep, brought out her magical sandwiches. If I’m the conductor, she’s the orchestral director. We’re partners working beside each other, and have done so for thirty-six years.

It always takes hours to get through the first two stacks of shelves, and these were more densely packed than ever. Cone 12 was down in the firebox, gradually 10, 11, and 12, began moving in Chamber I. We continued reducing the back chambers as needed. The tide was turning. The temperature began peaking at 2350F at the front, and we patiently rode the wave through Chamber II as it bored slowly back. Behind the bungs of small pots are two chambers of big pots. Here, the kiln is relatively empty and we have to be careful not to race ahead too quickly, for if the temperature gain is too rapid, and you over-fire, bloating can occur, and cristobolite begins to develop it’s deadly crystals. Cristobolite is a high temperature polymorph of silica with an unstable structure and a high coefficient of thermal expansion, which, when cooled, causes the pots to shatter. I knew you wanted to know.

Chamber V and VI, packed densely with dreams, presented the next challenge, and sure enough, we pushed through. Hamish in the firebox, keeping it steady, not over firing, Daniel and I with our banter on the sides making it happen, cap’n. Luke, Will, David, and Terry stoking the early chambers, handing us wood, and tidying. Stillman emerged bleary from the house, and plugged back in. All the elements were in place, but we couldn’t get the tapered back section of the kiln to budge.

It was time to admit I couldn’t do the whole thing myself, I didn’t have to stick every bit of wood in, but instead needed to take control of the finale, so I assumed my post at the pyrometer, and began waving my baton. Stoke now, wait, you do I, III, V, and VII on this side, and you do II, IV, VI, and VIII on the other. But wait for the temperature to peak, between stokes. No, don’t stoke yet. NO! WAIT! Do it again.

Sure enough she rose to an even and sustained high temperature for about 20 minutes. Daniel, exhausted from his activities related to installing a 350 feet long “conceptual fence” made out of clay columns, 18 inches wide and, some of them, 8 feet tall, at the North Carolina Museum of Art (to be completed soon), was sitting down, taking a break, alternatively nodding out and grinning from ear to ear at the resolution and harmony.

We had the kiln between 2330 and 2350F front to back, 35 feet long, 9 feet wide, 6 feet high in the middle. Not too hot, and not too cold, and just the right color, clean pale yellow with white wisps. The pots are at their most beautiful right then.

David Sutton commented later that the whole endeavor had been operatic, and at this moment it was as if Maria Callas was holding a long climactic note before the curtain fell.

But for us it wasn’t over, for then came the madness of salting. Hamish on the blower, Will pouring mugs full into the hopper, Stillman stirring. Eight in the front, four in each Chamber up one side, then up the other side. Then repeat up each side before the final salting up front. 150 lbs in all. Daniel and I stoked as needed, and once the salting was done, Terry brought the main firebox back up for a final 20-minute cleaning soak, after which we started the rapid cool. It was 7.25pm.

Done, but not done. Test rings pulled, every chamber checked for kissing pots, we separated a few with one of the long pokers, and righted a couple that had toppled into the ember beds between chambers. Minor damage, but all else looked good – glazes glistened, shapes shimmered. We were quietly elated. Time for a beer, or two, and time to rest, talk, peek in at the cooling pots, and wait for the temperature to fall to around 1600F at the back, in order to freeze the shine on the pots back there. We used to close the kiln down too early and all the lovely shiny glazes would crystalize and become matt and ugly.

The side stoking holes were clammed at 7.30pm, everyone left but Luke, Carol, and I. After showers we had supper, and I finally clammed the mouse holes and put the chimney cover on at 11.15pm. 1293F at the front, 1532F in the middle, 1606F at the back.

It was a long day, but thank goodness it hadn’t been the summer firing.