I've blogged here a few times in the past about the type of glaze firing I use to finish my work. I primarily fire in reduction, to cone 10, using propane gas at the Desert Dragon Pottery studio in North Phoenix. And in just the past year I've started to do some firing in oxidation in the electric kiln at my own home, to cone 6. Quick review: We measure the heat work in the kiln with cones, cone 10 is roughly (but not exactly) equivalent to 2350 degrees F. When firing in reduction, we are trying to starve the atmosphere inside the kiln of oxygen, so the fire will have a dynamic interaction with the materials in the clay and glazes. When firing in oxidation, you leave the oxygen alone and let it do it's thing. This does not require fire, so it can be done in an electric kiln. Actual fire is required for firing in reduction.
Reduction firing is not new to me, but firing with wood is something I have not tried. Like many many potters before me, I was intrigued by the idea. Pots that are wood fired have this warm, flashy, sort of delicious looking surface, you can really get a sense of how the flames licked the pot. They have a very unique look that's difficult to replicate with other firing methods. I'd Briefly considered the idea of trying to build a wood kiln at the studio, but with a full time job and plenty of other firing methods available it just didn't make any sense to pursue.
Then I saw the magical facebook post! Plans were brewing for building a small wood fire kiln at the Desert Dragon Pottery studio in North Phoenix, my home away from home studio! It's funny sometimes - you start considering something, and the opportunity for that something falls right in your lap. It's a clear sign that you had better dive in.
Leading the kiln building activities was John Manley, a ceramics artist from Nevada who spends at least a few weeks a year living and making work at the Dragon, and participating in some of our many craft fairs around the Valley of the Sun in the spring and the fall. The kiln is his design, and he bravely the led kiln building, and has led our first couple of firings as well - which was a no small commitment! We are so lucky John decided to share his time and knowledge for this project! For the week of the build, John brought along with him a friend and fellow ceramics artist Tom Bivins. Tom not only helped with the build but also generously shared his knowledge of kiln design, building, and firing with those of us participating. Tom lives in Idaho, and I've never taken one of his workshops or classes but I'm sure they are fantastic, because he's really good at explaining and describing ideas and techniques.
The kiln is very small by wood kiln standards, but a great size for our purposes at the Desert Dragon. A bonus of the small size is that we can fire it fairly quickly, normally a wood kiln can take days to fire. Ours is meant to be fired in well under 24 hours, though it will take some experimentation to figure out what kind of results we'll get from a 10-12 hour firing vs. an 16-18 hour firing. Wood kilns tend towards reduction on their own. We built the kiln in a way that allows us some control over the air flow, so we can affect the timing and amount of reduction in the kiln.
Here's some pictures from the build, I will let them tell the rest of the story.
We built a simple wood frame to help us construct the brick arch.
Shane hammers in the final bricks of the arch (left) and Tracy (bottom right) works on pulling the frame out of the arch, while John inspects the work.
The completed arch from the back, and starting on the chimney. The chimney, along with little slots at the back of the arch, will help to suck through the air from the front of the kiln out the back. The arched shape will help the heat and flames circulate evenly through the kiln.
Kiln shots! Me (top left, bottom right), Tom (top left), Tracy and Rose (bottom right), and John hammering some bricks into the top of the arch (bottom right).
Building the flue. These slots in the chimney, with kiln shelves we can slide back and forth to cover the opening a little or a lot, gives us a way to choke off the oxygen flowing through from the front the kiln. We can use this to increase or decrease the amount of reduction in the kiln atmosphere.
Tracy signing the kiln :) We covered the kiln arch with castable, and while it was still wet we placed all these large river rocks over it.
Not only do the rocks look cool, they help stabilize and insulate the kiln, We used simple cement blocks, and a couple really nice stumps that were hanging out on the Dragons property, to help keep the rocks corralled into place..
This is where we completed the official kiln building week. We still needed to add a few more feet to the chimney before our first firing. The fire will be in the very front, on top of a simple grate, and the pots will be loaded on the bricked surface behind it.
A shot of each of the first 2 firings. On the left, Chris and Doug stoke the kiln during our very first firing, while Mark and Mishy keep an eye on things. On the right, the second firing from just yesterday. As I write this post, the kiln is cooling - we hope to open it tonight or tomorrow.
The door is bricked up with 2 layers of brick, and we fill the gaps with mud as well as we can. It takes a little bit of attention to keep the mud from cracking and opening up gaps, so we babysit it a little with water and new mud as the firing progresses. We also have to continuously rake the hot ashes out of the bottom, so we don't block the airflow coming through from the front (there is some hot ash built up on the bottom right that we need to remove).
Our stoke hole is very simple, a hole in the door with a half kiln shelf propped up over it as a stoke hole door, and a chair and some bricks to give us a place to prop the kiln shelf/door when we stoke. We'd like to improve this in the future, but it works just fine for now.
Some of the pots from our first firing, most of these have no glaze on the exterior, or only on the top inch or 2 of of the exterior (though there is some red and white slip, and some red iron oxide stain used for decoration). The color and texture of the finished pieces is strongly influenced by the type of clay used. We are all so excited to see what the second firing has produced!