| Boiling Point No. 23 - December 1990 |
by Tim Jones, ITDG Ceramicist
The rationale for this method of firing is that by enclosing the pit that is used at present to fire traditional pots, the potters can control the firing to get a more even temperature throughout and prolong the firing so that the temperature has longer to penetrate the stove liners.
This is an intermediate step between the open fire method and a formally constructed kiln that would consume cut wood. By just enclosing the brushwood open fire with which they have considerable experience, the women should be able to continue to use brushwood and grass to fire the stoves. This will save them money now being spent on purchasing wood which is a major cost for the potters.
The kiln consists of a single brick wall surrounding a flattened area which is covered with bricks to make a star pattern floor (see diagram). The floor will cost more money but it will facilitate the cleaning out of ash after each firing. This is important to maintain the gaps between the bricks for the air to circulate through. There is a gap left in the surrounding wall for use as a loading door, this is bricked up and sealed before each firing. Four holes are left around the bottom of the kiln just above the floor to allow air to enter and to flow between the bricks in the floor.
For greater efficiency, though at greater cost the wall of the enclosed fire should be of double brick with an insulating layer of dry soil and ash in between. In this kiln the women build the usual bonfire over the liners with grass at the top to seal in the heat. Less grass is needed because the walls replace the grass down the sides. The door is sealed and the fire lit at the four air inlets simultaneously if possible. If there is a strong wind then the air inlet on the windward side could be covered slightly to balance the air being drawn in from the other three holes. The aim is to try to get a steadyfire burning through the liners on all sides at once.