Experimentation with the exact configuration of these split-bamboo kilns showed the
potters that the shape of the chambers could make a difference in how the temperature
in the chamber was regulated and also in reducing wood consumption. As new kilns
were built, the chambers slowly evolved into a more upright configuration with the
curved arches following the flame flow path rather than at right angles to it.
Because the flames were moving more slowly and circuitously through the large tall
chambers on their way to the chamber exit flues, they gave off more of their heat
energy inside the chamber, and did so more evenly throughout the chamber. This circulation
pattern, called crossdraft, was perfected to an art by these early Asian kiln builders.
How It Works
A modern noborigama is a series of insulated crossdraft kiln chambers linked together
which are running up a sloping hillside. Each chamber has flues leading into and
out of it where the flames can pass through on their way up the slope to the last
chamber. The sloping kiln itself creates a natural draft without the need for a really
At the bottom of the hillside, a large external firebox is attached to the first
chamber’s inlet flues. This firebox is used mainly to bring the first chamber near
to completion, and it is sized to also allow the rest of the kiln to be heated by
the waste heat coming off of the first chamber firing. A large portion of the total
firing time for a noborigama is used in stoking this large main firebox.
At the same time this change was taking place, the kilns tended to now be constructed
half recessed into the ground, and half above the ground out of bricks made of very
pure clays. These kilns resembled a piece of bamboo which was cut in half lengthwise
with the nodes forming the end walls of the chambers, and were called "split-bamboo"