I am now midway through my residency at Guldagergaard. We had a busy week firing two of the wood kilns. Ana, a Spanish artist and I got up early and started the fire at 5am. The pyrometer wasn’t working so we had no idea how quickly the temperature was rising, although we could see an orange glow inside the kiln. When the wood firing technicians arrived at 9am and put in a new thermocouple, we were amazed to find we had already reached 1100°C, a very fast increase in temperature indeed, so we were lucky that nothing had cracked. We had to let the temperature drop to 1000°C to do body reduction by adding hardwood, closing the dampers and restricting the air intake for an hour.
When we reached 1280°C Ollie the wood firing technician sprayed in a solution of soda ash in water. The soda reacts with the silica and alumina in the clay to produce a glossy glaze. We soaked the kiln at top temperature for several hours to even out the temperature between the top and bottom of the kiln. Ollie sprayed soda again and we finally put in more wood and closed up the kiln so that the glazes would be in reduction.
The next day we fired the Bourry box train kiln. This is a slightly larger kiln that encourages effects from wood ash falling and melting on the pots and flames from the burning wood flashing the surface orange.
The results were much more matt and crusty where wood ash and embers had fallen onto the pots.
I was very happy with some of the results but surprised by some of the glaze colours that had changed owing to the effects of reduction. My mustard yellow glaze turned black and my dark green lichen glaze turned blue-green.