My ceramics are either created on a potters wheel or hand-built. They are then wood-fired in an Anagama kiln. "The Anagama kiln is an ancient type of pottery kiln brought to Japan from China via Korea in the 5th century. An anagama (a Japanese term meaning "cave kiln") consists of a firing chamber with a firebox at one end and a flue at the other. (Wikipedia)". Unfired ceramics are stacked in a barrel vaulted chamber with a "firebox" at one end and a chimney at the other. The kiln is completely sealed except for a small opening to stoke wood through. An anagama works because the fire at one end produces a tremendous amount of ash and is drawn through the filled chamber toward the chimney. As the kiln heats up to temperatures approaching 2300 °F (1400 °C) the ash is super heated and creates a natural glaze covering the work.
An anagama is fueled with firewood. The kiln is fired continuously for approximately five days. This requires an enormous amount of wood,
my estimate is between five and seven cords of wood. Wood is consumed in the fire very rapidly and teams of potters are usually adding wood every few minutes
around the clock for the entire firing.
In the beginning, the temperature is increased slowly so the work does not crack from thermal shock. After around 800 °F the temperature is increased until it reaches the 2200-2300 °F mark. It is then held at that temperature for about 36 hours. This allows the ash and embers to build up on the pottery. Once the cycle has reached an end, the stoking hole is sealed up and the kiln is left to cool for seven days.
After the kiln is cool it is opened and the work can be unloaded. The woodfire process is very unpredictable. You are never sure when you unseal the kiln what will have happened. Pieces close to the firebox can be extremely crusted with ash, and those toward the back can be nice warm shades of brown or orange or any other color range. The firing process is fairly violent and sometimes the work is broken or cracked. It is really magical to unload the kiln and see what has happened this time.
Due to the enormous amount of work involved, anagama kilns are usually fired only a few times a year. Some artists only fire once a year.
I do most of my wood-firing at Roger Baumann's wood-fire kiln in beautiful Lake Peekskill New York. Roger is a magnificient ceramic artist and a patient teacher. Roger also takes people on tours of the woodfire regions of Japan. Check out his website for more information.