Tuesday, November 23, 2010

Clay + Fire = Awesome

I know it’s been a while since I updated the blog. I apologize sincerely for that, but I do have a good excuse… I just got married!

So with my lapse in tea discussion, I have a lot to talk about. Rather than going chronologically, which is just too predictable, I want to start with what happened this past weekend: a kiln firing.

I talked before about Willi Singleton, a local ceramic artist who, among other things, makes tea utensils. He trained for many years in Japan, and when he came back to this country he built a noborigama (a climbing kiln) on his property. The kiln is wood-fired, and it requires a lot of expertise to manage a firing properly. This past weekend I got to participate in one of those firings.

The actual firing began on Thursday afternoon, but it wasn’t until the last two days of the firing (Saturday and Sunday) that the helpers came in. Roughly, the process is this: Willi throws the pots and does the standard sorts of preparation – glazing, bisque firing – and then stacks the pots on shelves in the various chambers. The placement of pieces is crucial, because the flow of air (and especially airborne ash) through the kiln will determine how each piece looks. Certain glazes will produce a certain effect, but the temperature inside the kiln, air flow, and the ash itself all play into the process. It’s very unpredictable, but that’s what makes the end result beautiful.

Willi’s kiln has four chambers, but this time he was only firing two of them. The kiln is built into a hillside (hence the “climbing” part of the name), and the lowest part of the kiln is the firebox, which looks kind of like a fifth chamber. At the beginning of the firing process, Willi builds a fire in the firebox, and then gradually keeps the fire burning, building the temperature. Once the temperature inside the first kiln reaches a certain temperature, he stops stoking the firebox and starts stoking that first kiln, while simultaneously feeding the second kiln to prepare it for a full stoking. Once the second kiln gets to the right temperature, he starts stoking that one and feeding the third, and so on. Once the final kiln has been stoked for the right amount of time, he seals up all the holes in the kiln and allows the fire to smother out on its own.

Here’s a photo of the four chambers from the side. The brick archways covered over with the white substance (I think it’s some type of clay, but I forgot to ask) are actually the doors that Willi uses to access the chambers and insert/remove the pots.

I arrived Saturday night around 9:30. At that point, crews had already been working for many hours stoking the firebox. There were three people working the box, one on the central opening in the firebox, and one person each on two side ports. The photo below was taken when the openings were closed up, but you can see the opening in the middle and the ports above the cinder blocks:

The stoking has a rhythm. Someone (whoever has been designated to watch the fire) keeps an eye on air vents in the first chamber. When the flames coming out of the air vents fall to a certain level, someone tells the stokers to stoke – they all have to go at the same time – and the stokers at the ports remove the block closing the opening, add a set number of pieces of wood, and close the ports again, while the stoker in the center fills the opening with larger blocks of wood. Then everybody waits until the flames die down again, maybe 2-3 minutes.

This process continued for several hours. Along with the pots in the kiln are a series of 3-4 cones; I don’t know the technical details (maybe one of you can fill me in!) but when the first cone bends over and the second one is getting bendy, it’s time to move from stoking the firebox to stoke the first chamber. As luck would have it, that happened during my working shift, around 4 a.m.

Stoking the chambers is more difficult than stoking the firebox, because the goal is to keep the fire spread evenly throughout the kiln. Because the kiln is so wide, there’s one person on each side of the kiln, each stoking simultaneously. The stokers have to shoot thin pieces of wood through a hole that’s about six inches square into specific locations within the kiln. So, for example, Willi might say “two, two, two,” meaning that they have to shoot two pieces to the middle of the kiln, two pieces to a point that’s halfway between the middle and the edge, and drop two pieces on the ledge right below the opening. The stokers then keep an eye on the flames coming out of the vent holes above their heads, and call out to the other side when the flames are getting low. The goal is for the flames to go down at exactly the same time; if one side goes down too quickly, Willi (or the designated watcher) might tell the stoker to add just one more piece of wood to try to even it out.

As a rank amateur, I was given an easier job, feeding the second chamber. So after the stokers fed the first chamber, I put one piece of wood in the second chamber, alternating sides, so I was constantly moving back and forth. When they first started stoking the first chamber, I was literally running back and forth from one side to the other because they were stoking every 30 seconds or so; after a while, the pace slowed down to stoking every 1-2 minutes.

Here’s a photo of the process in action: there’s one person standing and watching the flame, and the person bending over is opening the access hole in preparation for stoking. (All of those photos were taken later in the process, when they were stoking the second chamber, but the principle is the same.)

Here’s another photo of the stoking process. You can see that one person is doing the actual stoking, and the person beside him is doing a secondary stoking to keep the fire even (and also fetching wood, which is a crucial part of the process).

And here’s Willi checking the progress of the pots:

My shift ended at 6 a.m., and I went to get some sleep. I came back to the kiln just before noon, at which point they were stoking the second chamber. The firing ended later that afternoon, but it’ll still be a while before Willi finds out how everything turned out – it takes about a week or so for the kiln to cool off to the point where it’s safe to go inside.

It was truly an amazing experience to take part in a firing like this, even though my part was a small one. There’s something really primal about tending the fire and watching its rhythms, and looking through the vent holes to see the pots undergoing their transformation. I can’t wait to see what comes out!