Monday, February 2, 2009

Raku 101

I was first introduced to the process known as Raku in 1976. I was in high school. My teacher took us out into the parking lot and had us set pots on fire using a kiln made out of bricks and a propane tank. It was love at first sight!
Raku has been done for 3000 years starting in Japan. However, it all changed in the 1950's or there abouts. I don't remember the exact date. Anyway, Paul Soldner was the first to take the pots out of the kiln and place them into some sort of combustible material and then smoked. He then washed them in cold water while they were still hot.
OK, since then people have been playing around with combustibles. The popular ones are saw dust - very dangerous if the area is prone to wind. News paper - gets a good flame but does not add any chemical to the glaze. Straw, leaves, or vegetable skins - leaves marks on the pot that can be a nice decoration. Wood chips - can add chemical like cedar resin, but hard to find. Magazines - shinny surface of paper is EPK so can enhance glaze color. Some people spay alcohol - interesting effects with glaze color. I have also seen people use a hand held torch latter to change the glaze color in a certain area of the pot.
Also how the combustibles are put into the metal garbage can is called the nest. You want the pot to sink down into the combustibles. So that it flames right away on as much surface as possible.
OH, before I forget, advice a heard from a teacher once. When you are ready to take the pots out of the kiln ------WAIT. The shinny surface from the glaze can only get more shinny. Then its time to set them on fire. The longer the pots are in the kiln the more mature the glaze becomes, the prettier the color.
As for washing the pots in cold water after being taken out of the smoker - DON'T!!!!!!!!!!
You are asking for cracks!!!!!Let the pots cool for awhile first. Raku already breaks the rules about clay. The pots are not supposed to be thermal shocked. Yet that is exactly what is happening to them. 15 - 20 min. in the kiln, 15 - 20 min in the smoker. All throwing mistakes will show up in technicolor. All bad craftsmanship in hand building will also be shown to you. Why ask for more cracks?
Once the pots are completely cooled then scrub them to get off the ash and carbon. Let them dry, then spray them with anything that will seal them. There are a variety of ways to seal them like lacquer, polyurethane, grout sealer, or floor wax. These are necessary so that the pots are functional.
The ancient way to Raku was the quick fire without the second stage of setting them on fire. I have experimated with this. With some vey interesting results. The pots still need to be sealed.
As for the glaze formula
Gerstly Borate 80%...................................I have used Nephline Synite instead.
Cornwall Stone 20%
then colorants - like copper carbonate, Iron, cobalt
I have also tried mason stains
I have even experimented with cone 05 glazes, they mature at the same temp.
The best part about Raku glazes is that the mixing does not have to be as exact. Also don't need to worry about seiving the glaze.
Most art schools and universities only raku once a semester. This is to bad. There is alot to play with here.
By the way the vase above is called "The Dancing Ladies"
She is one of my signiture pots. for more info.

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