In preparation for the upcoming Fall firing, Simon assigned me the job of building a bagwall inside the anagama.
A bagwall, as defined by Marc Lancet in he and Masakazu Kusakabe's book, Japanese Woodfired Ceramics, is "a wall or barrier used to direct flame within the kiln." In many kiln designs, a bagwall is built between the fire chamber and the ware chamber to regulate the flow of ash and heat into the kiln. Normally, a bagwall wouldn't be necessary inside this particular kiln. The reason we built one for this firing is that we will only be utilizing the first two levels of stacking space, leaving the back half of the kiln wide open. Without the bagwall, the heat would be sucked through the pots at too quick of a rate and therefore would make it much more difficult to evenly heat up the space that they occupy.
The style of bagwall that I constructed could be called "accordion." The bricks alternate at right angles creating holes that are not aligned with the flame path. The idea is that by making the heat/flame turn a corner before exiting through the wall, it will slow it down. The flame will roll back on itself in the space and linger amongst the pots, hopefully resulting in a more even heat distribution.
Each brick is dipped in kiln wash and dry laid. It is very important to make the first layer level and not wobbly to give the wall maximum stability. the measurement of the holes was about 2" x 3". The total amount of air getting through this wall should be roughly equal to the air getting out of the flue in the back. By this logic, these holes are probably a bit oversized. We may go back and partially fill in some of the holes.
I used a combination of 3" straights and standard straights, both hard and soft. Getting the sides to fit against the arch took some care and patience. I also made sure that I was building straight up and not allowing the wall to start leaning backward or forward.
And that's it! Can't wait to see how she works!!