In 2019 I had the unique opportunity to throw my own pots, and fire them in a Raku kiln.
Raku firing is a traditional Japanese pottery firing technique, typically involving removing the pottery from the kiln while it’s red-hot and placing it into a container filled with combustible materials, which ignite upon contact with the pottery – creating a oxygen starved atmosphere that produces distinctive patterns and colours which are totally unpredictable.
The kiln was constructed from an outer wall of common bricks, with an inner wall of refractory bricks – airy ceramic bricks with excellent thermal insulation properties. The lid was fiberglass insulation. Despite going to great lengths to insulate it, the heat was incredible. With the lid on it definitely kept us toasty in the inclement weather, but when the lid came off it was unlike anything I’d experienced before. And this was after my blacksmithing phase! Welding masks were essential for heat shielding.
In fact, when we dismantled the kiln there was a lovely bare patch where the grass underneath had been carbonised. Serious. Heat.
Fired by a large propane tank and burner, the kiln can reach about 1000°C. The pottery was first bisque fired in a indoor electric kiln, before special Raku glaze was applied (to most pieces). We glaze fired between 800-1000°C.
Throwing Pots
The pieces were thrown from specific Raku clay, course and designed to withstand the intense thermal shock of being taken out of the kiln at temperature. There was a bit of a learning curve – the majority of throws were a total failure and had to be binned or re-constituted, but every so often (and increasingly often) a good one would result.
The project focused on ancient pottery so I threw a range of pots and vessels, with my skills culminating in a huge amphora:
It was a bit wobbly, but a fantastic achievement in the time I had. I was very proud.
The pieces were then mostly Raku glazed. Some were left plain for Obvara and horsehair finishes.
Firing Day
We worked all day over the whole weekend to fire other peoples pieces as well. It was a bit chilly but very rewarding.
The Raku glazed pieces were taken out red hot, and put in hamster bedding (i.e. sawdust, no hamsters were harmed). As I said above, the altered atmosphere causes the glaze to crack, craze and take on amazing colours.
The unglazed pieces were treated in two ways: an Obvara finish or horse hair and feathers. Obvara firing involves dunking the hot pottery into what is essentially liquid bread. A yeasty mixture designed to seal the clay’s porous surface and make it suitable for food and liquids. It smelt pretty bad, but the results were amazing – with the best pieces taking on a fantastic tiger bread texture. The remaining pieces had feathers and horse hair applied to the surface. These organic materials vaporise on contact with the hot ceramic and leave a shadow.
It’s safe to say that beween the liquid bread, burning sawdust, horse hair and general sweat from being near a portal to hell, we smelt pretty awful at the end of the day.
Results
Unfortunately my big amphora fractured at the seam, but all in all a fantastic turnout.
