Building a Small Anagama Wood-Fired Kiln — Single-Chamber Climbing Kiln

An anagama requires a slope of approximately 15-20 degrees to create natural draft. The firebox sits at the bottom of the slope and the chimney at the top, so heat and flame travel uphill through the ware chamber. Select a site with good drainage and position the kiln so prevailing winds blow toward the chimney, aiding draft. Excavate a level trench into the hillside approximately 2.5m long, 1m wide, and 0.5m deep for a small anagama. The trench floor should follow the slope angle. Compact the soil firmly and lay a bed of dry sand or crushed firebrick as a foundation. Ensure the site is well away from structures and overhanging branches, as multi-day firings produce continuous smoke and sparks.

Lay hard firebrick on the trench floor in a running bond pattern (offset joints) using refractory mortar. Hard firebrick is necessary for the floor because pottery is loaded directly onto it, and soft insulating brick would crumble under the weight. The firebox occupies the lowest 60-80cm of the kiln length and should have a grate (either iron bars or a row of bricks on edge with gaps between them) to allow ash to fall through and air to enter from below. Build the stoke hole opening at the very bottom end — approximately 25cm wide and 30cm tall, framed with angle iron for durability. This opening is where wood is fed into the firebox during firing.

Stack insulating firebrick walls on either side of the trench, building them inward to form a catenary arch (the natural curve a hanging chain makes, inverted). A catenary arch distributes weight evenly without requiring a steel frame. The interior width should be approximately 60-80cm and the interior height at the crown approximately 60cm — large enough to stack several shelves of pottery. Use refractory mortar between all bricks, keeping joints as thin as possible (3-5mm) to minimize weak points. Build a temporary wooden form (a plywood arch template) to support the bricks as the arch closes at the top. Remove the form after the mortar sets. Leave one or two small peephole gaps in the walls for observing cone packs during firing.

At the upper end of the kiln, construct a chimney from firebrick, approximately 1.5-2m tall and 25-30cm square internal dimension. The chimney height determines draft strength — taller chimneys pull more air through the kiln. Include a damper slot near the base of the chimney (a gap where a flat brick or steel plate can be inserted to partially block the flue). Adjusting the damper controls the atmosphere inside the kiln: fully open creates oxidation, partially closed creates reduction. At the lower end, build a removable brick door in front of the stoke hole. The door is bricked up and mortared each firing, then broken open to unload. Leave gaps in the door bricks during firing to feed wood through.

Before loading any pottery, cure the new kiln with a slow first firing to drive moisture from the mortar and bricks. Start with a very small fire in the firebox and increase the temperature by no more than 50 degrees C per hour for the first 8-10 hours. Rapid heating causes steam pressure to crack mortar joints and spall brick faces. Bring the kiln to approximately 500 degrees C and hold for several hours, then allow it to cool naturally over 24-48 hours. Inspect all mortar joints and repair any cracks before the first pottery firing. A well-built small anagama typically fires to cone 10-12 (1280-1340 degrees C) during 3-5 day firings, consuming 2-4 cubic metres of split hardwood per firing.