Many artists were invited to come and work at the Institute of Ceramic Studies over the past year, but one of the most impressive was Peter Voulkos, who was here last spring (1995). With his assistant Peter Callas, he energetically made a number of plates. Peter Callas came back in October 1995 to fire the work made at that time. Let's look at Callas's anagama firing method.
The kiln is stacked with one row of shelves in the back to hold small pieces. Then the plates, some 60cm in diameter, are stood on their edges on either side of the kiln, facing the mouth. A total of 12 plates are stacked in this way, leaning against firebrick columns. Between the two rows of plates, Voulkos' "Stack," measuring 110cm tall, is laid on its side with its mouth facing the kiln's firebox. The middle part of the kiln, which is usually stacked with ware on shelves, is left open so that wood can be stocked to the back of the kiln.
After loading, the kiln door is bricked shut. The firemouth is usually closed with a single brick which is taken out and replaced for each stoking. Callas, however, fires in reduction, requiring more wood more frequently, so the firemouth cover is changed to a steel plate to facilitate stoking.
The firing is to take about four and a half days and use 200 bundles of red pine, plus 50 bundles of hardwood. (A bundle of wood in Shigaraki measures 40cm in diameter by 40cm long.) Sometimes the kiln is preheated with a kerosene burner, but this time wood is used from the start.
Since the plates are not bisque fired, the temperature has to be raised very slowly. At first the firebox is extended to prevent flame from directly hitting the plates and cracking them. After firing slowly in this way for about 20 hours, the kiln has reached about 300. With the danger of breakage past, the extended firebox is closed up and direct stoking through the firemouth in the kiln's door begins.
From here, the job is to raise the temperature up to about 1250. But with Callas' method, raising the temperature can be easier said than done. The scorched surfaces which Voulkos is known for are the result of heavy reduction. There are tow ways to reduce our anagama - cut off the secondary air below the firemouth, or open the air damper at the base of the chimney. But if reduction is too heavy, the kiln can't "breathe" and the temperature refuses to rise. Callas constantly makes minor adjustments as he studies the character of the flame and the rate of temperature rise.
When a wood-burning kiln is fired in reduction, the fuel is not completely consumed, causing charcoal to build up inside the kiln. As the firing Progresses, a mountain of charcoal accumulates up the middle of the kiln. It is this charcoal which creates the "scenery" on Voulkos's plates. Callas has planned for this effect as he decided how to position each plate in the kiln.
The firing continues, chopping wood, stoking the kiln, raking the coals, nothing the atmosphere and the temperature. The most important thing is to establish a rhythm in stoking to achieve a smooth temperature rise. The temperature is measured by an almost too-precise pyrometer equipped with a graph, where a pen unforgivingly registers the temperature once every minute. The graph becomes an ascending zig-zag pattern: the stoker watches for the temperature to peak, at which point new wood is tossed in. The temperature falls, then rises as the wood is consumed. When a new peak is reached (in about 8-10 minutes), it's time to repeat the process.
The kiln reaches 1200 after about 50 hours, and it is kept between 1200 and 1250, following the same zig-zag rhythm, for about 50 hours more. The comes the final spectacle.
When the wood is almost gone and Callas decides the kiln is done, he gives it one last stoking, stuffing 40-50 pieces of wood into the firemouth, until the kiln is full and can take no more. A pillar of flame shoots out of the chimney and brightens the Shigaraki evening sky. It takes 30-40 minutes for the kiln to digest that final assault. When the roar has died down, the firemouth is bricked up, the damper is closed, and there's nothing left to do but wait for the results. It has been 100 hours since the start of the firing. The beer is going to taste good tonight.