Raku: An Ancient Art
To briefly describe the raku process, we must understand that almost all other types of pottery are loaded into a cold kiln, where the firing proceeds slowly until the desired temperature is reached. This firing cycle may take anywhere from 8-24 hours or even longer. When the kiln has reached temperature it is shut off and allowed to cool enough to be able to remove the ware using bare, or lightly-gloved hands. The cooling cycle may last from 12-24 hours or longer. The ware is considered finished when it is taken from the kiln.
In raku, the pieces may be loaded into a cold kiln. The firing proceeds at a rapid pace with the wares reaching a temperature of around 1800°F in as short a time as 45 minutes. When the firing is determined to be completed, the wares are immediately removed from the kiln. Since at this point the glaze is molten and red hot, tongs are used.
The wares are immediately put into a container with combustible material such as sawdust, or leaves or newspaper and allowed to smoke for a time. Some of the effects are metallic and crackled-glaze surfaces and black unglazed clay. No two pieces are the same.
Raku firing is one of the most exciting and rewarding ceramic processes. The more you fire, the more you learn. There are so many factors that go into how your piece will turn out: the temperature you pull at, the temperature outside that day, how fast you go into the can, how fast the paper ignites, how long you hold the piece in the flames before you set it down, and how quickly you get the flames out when you put the lid on the can. That's just the part about pulling the piece from the kiln. It all really starts with the glaze you use, how well you apply the glaze, the reduction chamber you use, and how well you prepare it for reduction. All these factors determine how the piece will look and each time you fire you get to see how well you perform. Each time you open a can to uncover a piece, it is like opening a present to yourself.