The anagama kiln (Japanese: 穴窯) 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. Although the term “firebox” is used to describe the space for the fire, there is no physical structure separating the stoking space from the pottery space. The term anagama describes single-chamber kilns built in a sloping tunnel shape. In fact, ancient kilns were sometimes built by digging tunnels into banks of clay.
The anagama is fueled with firewood, in contrast to the electric or gas-fueled kilns commonly used by most contemporary potters. A continuous supply of fuel is needed for firing, as wood thrown into the hot kiln is consumed very rapidly. Stoking occurs round the clock until a variety of variables are achieved including the way the molten pots look inside the kiln, the temperatures reached and sustained, the amount of ash applied, the wetness of the walls and the pots, etc.
Burning wood not only produces heat of up to 1400°C (2,500 °F), it also produces fly ash and volatile salts. Wood ash settles on the pieces during the firing, and the complex interaction between flame, ash, and the minerals of the clay body forms a natural ash glaze. This glaze may show great variation in color, texture, and thickness, ranging from smooth and glossy to rough and sharp. The placement of pieces within the kiln distinctly affects the pottery’s appearance, as pieces closer to the firebox may receive heavy coats of ash, or even be immersed in embers, while others deeper in the kiln may only be softly touched by ash effects. Other factors that depend on the location include temperature and oxidation/reduction. Besides location in the kiln, (as with other fuel-fired updraft kilns) the way pieces are placed near each other affects the flame path, and, thus, the appearance of pieces within localized zones of the kiln can vary as well. It is said that loading an anagama kiln is the most difficult part of the firing. The potter must imagine the flame path as it rushes through the kiln, and use this sense to paint the pieces with fire.
The length of the firing depends on the volume of the kiln and may take anywhere from 48 hours to 12 or more days. The kiln generally takes the same amount of time to cool down.
In July we built an anagama at Pinkney Pottery, my home and pottery in the Cotswolds; together with the help of some friends, the kiln was completed in ten days.
About a week after the anagama kiln building workshop held at the International Ceramic Festival in Aberystwyth, Gas Kimishima and I met up at Pinkney Pottery in Wiltshire, the plan was to build an anagama kiln following medieval Japanese kiln designs. I had visited Gas about a year ago and seen his anagama, Moby in his secret woods, the curvy candle flame form, set in a clearing in the woods seemed like a piece of landscape sculpture itself. It was my idea to create a kiln similar to his, though its dimensions were to be a little smaller. Also I planned to follow the kiln building principles in the book ‘Building Anagama Kilns and Firing’ by Furutani Michio, who was a great Shigaraki potter and kiln builder.
Here is a day by day account of the kiln building stages and its progress to completion. The kiln bricks that we used were heavy industrial kiln bricks that I had got second-hand. I had prepared basic kiln building materials beforehand: about a tonne of fireclay from W J Doble in Cornwall, a tonne of silica sand, wooden posts, hazelwood branches from a coppice nearby, lath (thin strips of wood), chimney bricks from H.G. Matthews, a tonne of ballast from the local builders merchant and vermiculite. I also had a basic design of the kiln shape and dimensions taken from Furutani sensei’s book, the length of the main chamber was to be 2.5 metres, long enough so that I could lie down in the kiln without my feet sticking out.
The first day involved preparing the foundation and building up the incline, then laying ballast, coarse gravel under where the first row of foundation bricks were to be set. Next day, we laid the first row of bricks; though the completed Go-go-Gama was the creation of a Dream Team, it was decided that I lay each brick of the kiln myself. Though not accustomed to bricklaying, over the course of the week I had used muscles that I never knew existed. The mortar we used was a 2-1 mix of sand and fireclay, that I wedged between each brick and row.
Next was building the former, a device made of wooden posts, hazel arches and lath; this would hold the weight of the bricks as we set rows leading to the key-stone; once the key-bricks were set it and the mortar dried, the former would be taken out. Over the weekend some friends arrived to lend a hand in the kiln build, Dameon Lynn and Sim Taylor, without whom the kiln build would have taken several more days. Some of the bricks needed to be cut as we were fitting the keystones and Sim lent his expertise in chiselling while Dameon was busy mixing the mortar. Once the main chamber was finished we laid bricks arching over the smoke channel and then made the octagonal shaped chimney.
Each evening after the hard work of kiln building was over, Gas and I played chess, a game that he excels at and to this day I have never beaten him. One night he played a spectacular game winning after a queen and knight sacrifice.
Before the kiln was built I had already decided on a name for the anagama, it was to be called Go-go-Gama 五合窯. The name is taken from the hermitage of the 18th century zen monk and poet Ryokan who lived in a tiny hut in the mountains of Niigata prefecture near the Sea of Japan which he called Go-go-an. The pair of lion-dog statues that guard the kiln also needed a name and following Gas’ suggestion, we decided to name them Ryo-chan and Kan-chan.
After a brief visit to go to a Potfest in Cumbria and to enjoy some Lakeland scenery, we returned to Wiltshire to finish the kiln, all that needed to be done was to make the sutema wall, a wall at the back of the main chamber with exit flues that serves to keep the heat inside the kiln and also to create back pressure. On last day we cut and laid bricks to form the rounded front of the kiln and the firemouth.
This ten day anagama build was a very memorable one, and I wish to thank all those who lent a helping hand. The first firing is scheduled for the last week of October and in the meantime this potter will be busy in the studio making pots as well as sawing and cutting large bundles of larch off-cuts from a nearby saw-mill. But as they say, the proof is in the pudding, after making some pots and firing them well, maybe Go-go will show us a little of the beauty of wood-fired pottery.
the wind brings enough
of fallen leaves
to make a fire
たくほどは 風が もてくる おちば かな
良寛大愚 Ryōkan Taigu (1758–1831)