Above: Raku cans wait under ventilation hoods.
Taking a few steps back and beginning at the beginning, I should mention that apart from photography, ceramics was always my favourite medium and I took several courses during my two years of BFA studies (At NSCAD and at Concordia). I don't know what it is about ceramics that I love so much, but certainly my pyromaniacal tendencies were satisfied by it (if nothing else!).
Raku is a form of glaze firing. For the uninitiated, the ceramics you use in everyday life (dishes and plates and cups, to name a few items) are all glazed, because glaze keeps the still-porous clay from absorbing what comes into contact with it (food or liquid, for example). Before being glazed, ceramic "greenware" (unfired/raw clay pieces) is fired once in what's called a bisque firing, a low-temperature bake that hardens and strengthens the clay so that it is much less easily broken. The "bisque-ware" is then glazed: glaze is often applied liquid and allowed to dry. Then another ("glaze"-) firing takes place during which the glaze vitrifies, fusing with, and creating a protective layer over, the clay.
Outdoor Raku kiln, with gas pipe attached at right:
Raku firing is a unique glaze firing process that involves a low-temperature form of reduction . Reduction firing requires some form of combustion (flame), and usually takes place in a wood or gas kiln. The process involves strategically cutting off the oxygen supply to the kiln, which causes the fire to draw oxygen from the clay body and glaze, causing a chemical reaction that produces a wide variety of glaze effects (especially at high temperatures). In Raku glazes, this process often creates a fascinating metallic look.
Waiting for the kiln to heat up:
The Raku process involved an outdoor kiln in both the contexts where I participated. A gas kiln is heated outside, and when the Raku ware is glowing hot and the glaze is molten, the lid of the kiln was lifted and the pieces were removed with tongs and placed in metal trash cans containing sawdust, with relatively airtight lids. At NSCAD, we were encouraged to lift the lid after a few seconds and toss in another handful of sawdust to increase the reduction effects (in theory; the real reason was that this trick often produced a "fireball" that belched from under the lid of the can). At Concordia this was considered too much of a hazard (*cough* sissies *cough*).
Shifting the cans to a spot underneath ventilation:
When the red-hot ceramic pieces land on the sawdust, they ignite it, creating flames that require oxygen. The lid of the can prevents air getting in, and thus the flames take oxygen from the glazes instead, creating a reduction environment in the can (hence the fireball).
After about fifteen minutes, the cans are opened and the still-hot Raku ware is carefully removed with tongs.
The Raku pieces are dunked in buckets of cold water to cool them, and to help rinse off the sawdust, soot and other detritus. Unglazed clay body will usually have turned black at this point, from the smoke and soot of the reduction process.
Finally, the freshly glazed Raku ware is left to dry and cool on the grass near the courtyard.
Raku is the perfect firing in which to participate if you love smelling like woodsmoke at the end of the day. There's also something deliciously visceral about creating objects in this way. It's all chemistry and physics, in a very hands-on, immediate and aesthetically exciting experiment, and a great group activity in which everyone has a part in helping create something unique.
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