⟁ cover painted for this edition — the source module carried no illustrations
Complete Wood Firing: From Kiln to Ash Glaze
Wood firing produces unique surfaces through ash deposit, flame marking, and atmospheric effects impossible to achieve with gas or electric kilns. This campaign covers wood kiln types, stoking strategy, ash glazing, and firing schedules.
Chapter 1: Wood Kiln Types
Kiln Type
Origin
Chamber
Firing Time
Temperature
Anagama
Japan
Single long chamber
3-7 days
2300-2400°F
Noborigama
Japan
Multiple climbing chambers
3-5 days
2300-2400°F
Bourry box
France
Downdraft, separate firebox
12-24 hours
2300-2400°F
Train kiln
Various
Long, narrow, multiple chambers
2-5 days
2300-2400°F
Cross-draft
Various
Simple single chamber
12-36 hours
2300-2400°F
Chapter 2: Wood Fuel
Wood Type
BTU/Cord
Burn Rate
Ash Content
Best For
Oak (red/white)
24-28 million
Slow
Medium
Sustained heat
Pine (softwood)
15-20 million
Fast
Low
Quick temperature rise
Maple
24-26 million
Moderate
Medium
Steady heat
Ash (tree)
20-24 million
Moderate
Medium
Good all-purpose
Cedar
13-16 million
Very fast
Low
Kindling, quick heat
Wood preparation: 1) Split to 2-4 inch diameter pieces. 2) Length: fits firebox (12-24 inches typical). 3) Dry for 6-12 months (below 20% moisture). 4) Wet wood wastes energy evaporating water. 5) Stack in covered area with good airflow. 6) A 3-day anagama firing requires 3-5 cords of wood.
Chapter 3: Firing Strategy
Phase
Temperature
Duration
Stoking Rate
Goal
Warming
Room temp to 500°F
6-12 hours
Small, infrequent
Drive off moisture
Water smoking
500-1100°F
4-8 hours
Moderate
Complete water removal
Oxidation climb
1100-1800°F
8-16 hours
Steady, increasing
Build temperature
Body reduction
1800-2100°F
4-8 hours
Heavy, fast
Reduce atmosphere
High fire
2100-2400°F
12-48 hours
Continuous, heavy
Reach target, ash deposit
Cooling
2400°F to room temp
3-7 days
None (sealed)
Slow, even cooling
Stoking technique: 1) Side-stoke (through side ports): small pieces, frequent additions. 2) Front-stoke (through firebox door): larger pieces, less frequent. 3) Side-stoking creates more ash in the chamber. 4) Front-stoking provides more even heat. 5) Alternate between oxidation and reduction for complex surfaces. 6) Reduction: close damper, heavy stoke (smoke = carbon monoxide). 7) Oxidation: open damper, light stoke (clear exhaust).
Chapter 4: Ash Glazing Effects
Effect
Cause
Appearance
Natural ash glaze
Ash deposits melt on pot surface
Green, amber, brown glass
Flame marking (hidasuki)
Straw wrapping burns, leaving marks
Orange-red lines on white
Carbon trapping
Carbon locked under ash glaze
Black spots under glass
Flashing
Flame path across unglazed surface
Orange, peach, warm tones
Wadding marks
Wadding under pot prevents sticking
White circles on bottom
Kiln shadow
One side faces flame, other sheltered
Dramatic light/dark contrast
Natural ash glaze: 1) Wood ash contains silica, alumina, and flux (calcium, potassium). 2) At high temperature, ash melts into glass. 3) Ash accumulates on surfaces facing the firebox. 4) Heavy ash deposit = thick glaze (dripping, flowing). 5) Light ash deposit = thin glaze (dry, matte). 6) The composition of the ash (wood species) affects the glaze color and texture.
Chapter 5: Loading and Kiln Care
Loading Factor
Consideration
Effect
Position near firebox
Heavy ash, intense flame
Thick ash glaze, dramatic effects
Position in middle
Moderate ash, even heat
Balanced effects
Position near chimney
Light ash, less flame
Subtle effects, flashing
Tight loading
Restricts airflow
More reduction, darker surfaces
Open loading
Allows airflow
More oxidation, lighter surfaces
Wadding
Prevents pots sticking to shelves
Essential (alumina + kaolin)
Reference Card
Wood firing is a marathon (a single firing can last 3-7 days with continuous stoking every few minutes; teams of firers work in shifts around the clock). 2. Ash is the glaze (in wood firing, the glaze comes from wood ash that settles on pots and melts at high temperature; no commercial glaze is applied; the kiln creates the glaze). 3. Position determines surface (pots near the firebox receive heavy ash and intense flame; pots near the chimney receive subtle effects; every position in the kiln produces different results). 4. Dry wood is essential (wet wood wastes energy evaporating water instead of heating the kiln; wood must be split and dried for 6-12 months before use). 5. Reduction creates depth (restricting airflow creates a carbon-rich atmosphere that produces deeper, more complex colors; alternating between oxidation and reduction creates the most interesting surfaces). 6. Every firing is unrepeatable (the combination of wood species, loading pattern, weather, stoking rhythm, and kiln atmosphere creates unique results; no two firings produce identical surfaces). 7. The kiln is a living thing (wood firers speak of the kiln as having a personality; learning to read the kiln's behavior through flame color, sound, and draft is essential to successful firing). 8. Wood firing connects to the deepest pottery tradition (for thousands of years, all pottery was wood-fired; the surfaces produced by wood, ash, and flame are the original ceramic aesthetic).
