Over the past couple of days a group of us current ceramics students at HDK along with some alumni, have come together to pack the 3.5m square anagama kiln at Nääs along with our smaller wood firing kiln ‘Elinor’. We’ll begin firing early Monday morning, working in shifts of four hours per pair until Wednesday night when the anagama reaches about 1300C. Elinor can be fired to temperature in one day so on the Monday we’ll be feeding two kilns simultaneously.
We began by emptying all our boxes and unwrapping our glazed pots. The anagama needed to be swept out before the kiln could be packed and wadding had to be prepared. The recipes for wadding vary but we used approximately 7 parts Alumina to 3 parts Kaolin (China clay) alongside rye, water and a generous shake of sawdust. This makes up a kind of off-white putty which is rolled into small cocktail sausage shapes that stick all the kiln shelves and supports together. Since the anagama slopes inside, the supports don’t lie flat but are angled on the base and need to be stuck down. Small balls of wadding are spat on and stuck to the base of pots before they’re placed in the kiln. It can be knocked off after the firing but without it the coating of ash through the kiln could stick everything together.
The chun type glazes were placed closer to the back of the kiln because they’re liable to run while glazes that required higher temperatures to melt were put close to the opening where the flame can hit them. Unbisqued work was also put to the back to avoid cracking. This is one of the differences between an anagama and an ordinary wood kiln – in a wood kiln the pots are shielded from the flames while in an anagama they are exposed to them. The temperature is also encouraged to fluctuate in this firing e.g after 1260C we will drop down to 1220, then up to 1270, down to 1240 and so forth to climb steadily, building up lots of layers of ash. We’ll have a pyrometer in the kiln but have also placed eight lots of seven pyrometric cones ranging from 1000C to 1325C in order to measure the temperature difference throughout. These cones are visible in the peep holes down either side of the anagama’s length.
Today we also prepared the daub to seal in the bricks at the kiln’s entrance – 50/50 sand and clay which could be dug up just a few meters away from the kiln, with added water to make a paste. A space for the firebox was kept at the front – here we can push in wood to feed the fire. The base of the entrance is built with alternating columns of soft and hard bricks so that the soft ones can be removed if needed to take out fuel from inside. Around the door too are hard bricks as supports. Some of the bricks at the front had to be sawed and sanded down to make them fit as tightly together as possible.
When packing it’s important to think of how the flames will flow. Like water they will always take the easiest route so it’s good to have a range of heights on each shelf and nothing too large close to the back which could block off flames to the smaller pots in the narrower end. Since we didn’t have quite enough work to fill Elinor, soft bricks were places in the gaps which will keep the air flowing evenly throughout. Generally the packing hasn’t been an especially difficult process, it just takes a lot of time and shuffling things around. Fingers crossed for the next step!