We build a kiln with Elina and Monika. The construction was simple. Old bricks formed a square base for the fire ( ~40x40x20) with a half-a-brick size vent on the side opposing the opening. Bricks were laid to form a ~60cm shaft and a steel grill built in the middle. We used ceramic tiles on top of the grill to support the ten(ish) items we burned. The shaft was covered with a steel plate to keep the temperature. The opening had a partial brick door and holes in the kiln walls were filled using a clay/sand mixture for insulation. I had small bellow for building up temperature and a electric fan for building high heats (from Jesse).
The firing had three phases. 2 hours low heat using only wood as the fuel (this failed as the temperature rise too fast breaking an item), 2 hours of medium heat with more wood and energy form the bellow pumping up the temperature and 2 hours extreme heat with charcoal and the electric fan for extreme temperatures. We suspect we reached temperatures above 1100°C because a store bought glazing designated for 1050°C we used was burned. Some pieces which were closest to the heat also burned and showed charred glazed like surfaces, indicating the clay turned into lava.
While heating we practised forging using scrap metal bits and rail track for an anvil.
It took a day to build the kiln and prepare the firewood and a day for the firing. The items were left cooling over night. We used various clays and mixtures for the objects but clay from Kurängen spring worked best. We suspect it has sand particles in it which prevent extreme shrinkage, helping the items to not break in the heating. A thick jug I made from clay (partially found from the basin of the spring and three meters north east from it) is thick enough that contains water even without glazing.
We will do a new firing next month for glazing and making new things. For the glazing we’ll use a 1:2 ash and 1:2 clay mixture. The ash is from wood produced by the first burning and the clay from Kurängen. I’m in the process of washing the ash. The recipe and science comes from Phil Berneburg. We’ll build a bigger kiln and aim for a steadier pre-heating phase.
Using clay from a spring, to drink its water completes and begins a ritual a geoartistic-cycle. It feels powerful and I love that the process of preparing clay objects is thoroughly holistic: Using ashes from the first burning for the second burning glazing feels like a gaiaistic design. We also prepared small cups, which I’ll built a wooden tray for. The long term plan is deposit the items submerged into the Kurängen spring water, were they can be used by visitors and forest dwellers. The design of the items is utilitarian. The cups which we made don’t have any straight edges, which works well for the forest as it does not have any straight edges either.
A visit to the spring in long due. I should groom the garden of peat I planted.