Because my studio is in a business complex, there is nowhere to do raku firings here. So my raku kiln lives in Bristol, WI at Bristol Pottery, the studio of my friend Fred Gregory. Fred's got several acres of land, and open burning is not usually a problem. However, due to the severe drought that plagued the midwest this summer, the village of Bristol issued a burn ban two days before we were set to start firing. So the second half of the raku workshop was put on hold until the ban was lifted and my schedule opened up again.
So this weekend I finally had time to finish up the workshop. The kiln worked great and we got some wonderful pots finished. I'll post photos of finished pots as soon as I shoot slides of them.
For those of you not familiar with rak firing, here's how it works: We make and bisque fire the pots like always, but the glaze firing is totally different. After applying the raku glazes, we fire them up to 1850F degrees in 20-30 minutes. Then they are pulled from the kiln with long tongs and placed in a bed of combustible material (sawdust, newspaper, whatever) and covered with a can. We call this the post-firing reduction. 'Reduction' in this case means reducing the amount of oxygen- the burning material eats up all the oxygen in the can. This reduction causes the copper in the raku glazes to flash lots of bright colors, and causes any exposed unglazed clay to turn black from absorbing the carbon from the smoldering material. About 30 minutes later the pots are cool enough to be removed from the cans. Done!
|My raku kiln|
|Moving a pot into the post-firing reduction.|
My raku kiln is built of soft brick, with a hinged front door. In my opinion, this is the safest way to raku fire. From a safety standpoint, I have a real problem with the fiber-lined expanded steel mesh type raku kilns that require you to lift the entire body of the kiln off in order to access the pots. I think that opening one of those kilns and releasing all that heat is one of the most dangerous things potters do, not to mention the health risk of breathing the fibers that are released every time the kiln is moved. I honestly can't believe they are allowed in schools. My kiln allows someone to open the door just enough to get to the pots, and then close it again. Only the person pulling the pots is exposed to the heat of the kiln, and he/she wears protective clothing. The risk of getting burned is very minimal, and there are no fibers to breath. The other benefit of my kiln is that we can fill the kiln with up to a dozen pots, and the last one comes out nearly as hot as the first. The hotter it goes in to the post-firing reduction, the better is will look. My kiln has one power burner underneath, and the whole thing is on wheels so it can be rolled outside when we need to fire.