One unique feature of the kiln is that there is no impediment to flame and ash striking the work as air moves through and out of the kiln (for the technically-minded, the kiln is a blend of an anagama and a groundhog kiln). Early in the firing, the flame is too short to reach the work, but the ash settles throughout. The length of the flame grows until it stretches through the kiln as the amount of wood is slowly increased.
As the flame plays over the pieces, it pulls oxygen from the clay and glazes (a process called reduction) producing darker and lighter brown and red-browns to cream and gray. The color patterns shift as the flame constantly moves, following the stoking pattern in both location and pace. Late in the firing ash melts forming a natural glaze ranging in color from yellow-green to dark green, depending on the wood used. If the kiln gets hot enough, the ash can have a high gloss. If cooler, ash won’t fully melt and a sugary surface results. In addition, the ash changes the behavior of other glazes causing them to run, crackle, and fade.
Vase 4b, 2007
About one-and-a-half to two cords of dead wood collected from fence lines and fields are used for a firing. Three people need about two days to load the kiln. A firing takes three days during which the kiln will require constant monitoring. After cooling a least a week, the kiln is unloaded, but several days may be needed to clean the shelves for the next firing and to prepare the finished work for sale.
The dramatic effects of woodfiring complete my work and tie it together. In the kiln, flame and ash directly and strongly interact with the clay. Flame colors the work and ash forms a natural glaze. At temperatures above the approximately 2,250° F that the ash melts, the color palette is reduced to earth tones and some greens and blues that will withstand the strong bleaching action of the firing