FIREBOX
(download the msword file)

In preparation for this presentation on kiln design I took time to reflect on some of my early influences. After a short immersion in the works of Shoji Hamada, Bernard Leach and medieval Japanese pottery things really began to click with my relationship to Peter Callas and Peter Voulkos in 1981.  Their abstract expressionist approach to image and their use of extended wood-firings, to develop rich surfaces, resonated for me.

In 1983, as a graduate student at the University of Montana, I had the opportunity to build my first single chambered tube kiln.   This kiln was a straight tube placed on a slope of 15 degrees with a modest interior dimension of 5’x 5 1/2’x 15’.  Since that time, I have built four other anagama-type kilns based loosely on the “pear-shape” design. The early “pear-shaped” porcelain kilns of China piqued my interest primarily because the front of these kilns were wide and offered, in a contemporary context, the potential for significant firebox exposure.  

My current kiln, the Kegonsa Anagama, was designed to maximize the front stacking area in which numerous pieces are in direct contact with the embers. About 1/3 of the total amount of the work stacked in the kiln is essentially in the front firebox region. Firings typically are 7-8 days in duration. My primary goal with this kiln is to develop complex firebox surfaces that compliment my sculptural works. I apply layers of slip and glaze to my pieces and subject their surfaces to the effect of the embers over an extended period of time at high temperature. Using slip and glaze in this manner serves to broaden the palette of the natural ash glaze. Pieces throughout the entire kiln collect a significant amount of fly ash as a result of the wide front, low arch, and the minimal overall slope of less than 10 degrees. The kiln’s tapered back lends itself to a more reduced atmosphere, increased flame velocity, and significant local flashing creating surfaces that compliment those produced in the front of the kiln. Six stoke holes along each side provide numerous options depending on the firing strategy. Some of these stoke holes serve merely as spy holes for checking cones and surfaces.

The most important features of this kiln, that I have found to be very exciting and useful, are the three stoke holes in the front of the kiln. Much of my focus, in terms of object making, has involved sculptural work placed between the channels extending into the kiln from these stoke holes. I slowly heat the kiln for the first 3-4 days using the center primary air hole in the bottom of the door and then I move to the center top hole at about 1200 F. As temperature is gained and embers fill this middle channel, I begin to stoke the front right and left holes. The right and left holes help to heat the sides of the kiln and efficiently move the front kiln temperature up to the point of ash melt. Of course, the right and left channels also begin to fill with embers. I can maintain the embers in all three channels, at ideal levels, by stoking the middle or side holes as necessary. Once “meltdown” has been achieved in front of the kiln, I can hold this temperature indefinitely and begin heating the back of the kiln using the side stoke holes. The sculptural pieces that are stacked in the front become surrounded by ember which provides a beautiful full-round effect. These channels are intimate spaces and I am able to adjust the level of the embers with great control and strike desired “crust” or transitional lines on each piece.