Japanese Raku tea bowls date from the 16th century when a potter named Chojiro fired handmade tea bowls at low temperatures and then plunged them straight from the kiln into a bath of green tea. The resulting unpredictable colors and patterns became known as Raku. Chojiro changed the family name to Raku and 15 generations have continued to make the tea bowls and museum quality pottery. American potter Paul Soldner developed a new way to make Raku bowls when he accidentally dropped a hot piece into a pile of leaves which ignited and created interesting patterns in the glaze. Soldner's adaptation of the Japanese tea bowl method is used today by Western potters.
Items you will need
- Handmade bisqueware or wet clay
- Roller (optional)
- Raku glazes
- Pottery tongs
- Safety goggles and fireproof gloves
- Galvanized tub with cover
- Shredded newspaper, sawdust, leaves or hay
- Hose with fine spray nozzle (optional)
- Bucket of water (optional)
Make the bowl by kneading the clay to work all the air bubbles out of it and then rolling it out about 3/8--inches thick. Trim the clay into a circle and work the circle into a bowl shape with a flat bottom with your hands. Fire the unglazed bowl in an 1800 degree Fahrenheit kiln to strengthen it. Use readymade bisqueware only if you have no access to clay to make your own. Ideally, Raku is wabicha -- humble, handmade, imperfect and a personal start-to-finish tea bowl.
Apply Raku glaze, either an original formula or a commercial glaze, to the outside of the bisqueware. Let the glaze dry.
Put the glazed bisque in a kiln at 1800 degrees Fahrenheit for 40 minutes. Cover your eyes with protective goggles and put on fireproof gloves when working with a hot kiln.
Remove the molten, extremely hot bowl from the kiln with a potter's tongs. Stand back enough so you are not breathing fumes when you open the kiln. It is useful to have two people, wearing protective gear: one to open the kiln and one to remove the bowl.
Plunge the bowl into a galvanized tub lined with shredded newspaper, dried leaves, sawdust or hay. Be careful because the flammable material will burst into flames as it comes in contact with the hot pot. Allow it to burn for a few minutes and then cover the tub to extinguish the flames and start the reduction process. Reduction happens when the oxygen to the fire is cut off and the fire tries to draw oxygen from the piece, releasing the colors in the glaze. The carbon produced is absorbed by the unglazed parts of the bowl, turning them black.
Remove the cover from the tub and avoid breathing any fumes. Use the potter's tongs to lift the bowl from the tub. Either spray water on the piece to freeze the colors or submerge it in a bucket of water. Place the bowl on a rack to cool.
Sponge off, rub or wipe the finished cooled bowl to clean any particles of soot from it and reveal the final design.
Tips & Warnings
- Err on the side of caution by wearing your goggles and protective gloves whenever you work at the open, heated kiln. Singed eyelashes and burned fingers are no fun, and when the kiln is opened after firing, escaping fumes can be dangerous.
- Wear cotton clothing and covered shoes when working around a kiln and the fire pit. Never wear flammable synthetics that could melt in the presence of extreme heat.
- Unburned gases can spontaneously ignite when the lid is removed from the tub. Be alert to this possibility and exercise caution to prevent an accident.
- If you are concerned about the possibility of fumes, wear a respirator while working.
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