â€œ The pots emerge as the creation of the â€˜combat between the clay and the fireâ€™ within the kiln.â€ (Cort, Shigaraki, p. 297, quoting Kobayashi Hideo)
While these pictures may look like two different pots, they are actually pictures of two sides of one of my teapots, with no applied glaze. It was wood-fired for six days to a maximum temperature of 2400F (1325C) in the two-chamber kiln of Tony Moore, a sculptor living in Cold Spring, NY. (www.woodfiring.com/TONYMOORE.html). After loading and bricking up the kiln, stokers on eight hour shifts threw wood into the firebox every five or six minutes, the timing of the stokes dependant on the fire, smoke and sound of the kiln, the movements of the pyrometer and measuring cones, and the firing plan. When the firing ended, all openings into the kiln were closed and the ware was given six days to slowly cool.
The surfaces that you see in the pictures are caused by (1) particles of wood ash settling on the pot and melting, forming a glaze, (2) the path of the ash and the flame, and (3) the volatile gasses within the kiln atmosphere. The side of the pot pictured at left faced the flame and the ash settled on it, melted, and ran down the side of the pot. The other side, pictured at right, faced away from the flame and received virtually no ash. The surface of the second side is a result of the action of the kiln atmosphere on the unglazed clay. Also, the particular clay used (a porcelain), and the placement of the pot within the kiln (near the front of the first chamber), dramatically affected the surface.
The results of a wood firing are highly unpredictable. The surface will vary from kiln to kiln, and from firing to firing of the same kiln, depending on the design and construction of the kiln. Other variables include the duration of the firing, maximum temperature and firing schedule, the amount of ware and the way it is stacked in the kiln, the type and dryness of the wood, the stoking patterns, the weather conditions, and the length and conditions of the cooling. Thus, wood firing is perfect for those of us who invite risk and are willing to fail in order to achieve the occasional sublime result.
I am currently building my own two chamber wood-fired kiln in upstate New York. The design is based on a combination of 16th and 17th century Japanese kiln designs. A major influence on my design is a kiln built by Shiho Kanzaki, a potter from Shigaraki, Japan, on Karl Beamerâ€™s property in Bloomsburg, Pennsylvania. I helped Karl fire the kiln last March, and loved the way it fired and the results. (I recommend Shiho Kanzakiâ€™s website. The first chamber of the kiln will provide maximum direct exposure to ash and flame, while the second chamber will allow more subtle results and be amenable to glazed work. We just finished pouring the concrete slab and will start building when the bricks are delivered.
Why do I fire with wood, when gas or electric firings are so much easier? Principally because the surfaces from a multi-day wood firing suit my pots and my aesthetic, and because I find the process and itâ€™s historic connections engaging. I also enjoy the communal aspects of wood firing – both the wood-firing community (a truly international one which is having a convention in Flagstaff, Arizona from October 11-14, which I will be attending) and the communities, which form around each firing. An extended wood firing requires a group – potters who put work in the kiln, and friends and family. Each group develops its own bonds and personality, culminating in the opening of the kiln when the successes and inevitable disappointments of the firing are revealed.
What I like most about my teapots is the way they reveal me and the process of their making â€“ the designing, choice of materials, fabrication and firing â€“ a revelation I like to think I share when the teapot is used.