I (James) found it necessary to make some improvements to the Tube, one was a roof extension to increase weather protection during the fall and winter and to increase the insulation on the Tube. When I fired the kiln it was almost unbearable to to be around even in mild weather and the cooling was much to quick for my taste. So after some discussion, gathering materials that were almost forgotten about, and preparation the new improved Tube will be functional just in time for the Symposium and long into the future. The kiln was constructed with one layer of these strange wedged shaped bricks, making the walls only 7 inches thick, and when the kiln heats up many gaps between the bricks appear. Trying to utilize what we had on hand, the back up insulation is varied. The main and left side stoking area are backed up with 3 inch soft brick and the remaining sides are insulated with either 1 or 2 inches of Fiberfrax panels.
The layer above the arch is a combination of soft brick and fiber. All this is covered with chicken wire and steel around the stoking doors and spyhole to keep these areas stronger and protected. The stucco for the sides consists of 2 parts screened concrete (to remove large stones), 1 parts fireclay, 1 part silica sand or coarse grog, and 3 parts vermiculite, mixed and troweled on smooth. The arch is receiving a looser coating of stucco of 2 parts concrete, 1 part clay, 7 parts vermiculite. It's already looking like a different kiln.