Raku originated with the Japanese Tea-masters because of its practicability for tea bowls. The Tea-masters, influenced by Zen Buddhist philosophy, took a unique pleasure in this conscious return to direct and primitive treatment of clay. The Japanese character for Raku ranges in meaning from ease, comfort, or enjoyment, to happiness.
The pots are fired in a special small kiln, which only holds a few pots at a time. While the kiln is being heated to between 1500°F and 1800°F (815 °C - 982 °C), the pots to be fired are glazed and put on top of the kiln to dry. After they are dry, and when the kiln is at an adequate heat, the pots are placed in the kiln with the help of long tongs. The glaze is allowed to melt taking from five to ten minutes. The piece is then removed with the tongs and placed in a metal container filled with leaves, newspaper, or any such combustible material. More material is thrown over the pots and the container is covered. The stifled fire is allowed to smoke for 1-5 minutes, after which the pot is retrieved and allowed to cool slowly or sometimes plunged into a bucket of water for a few seconds. As the glaze cools rapidly, it tends to crackle, and the smoke will fill the crackle as well as the porous clay pot.
Raku pieces will "sweat", use a plastic baggy liner or a small glass jar inside to keep cut flowers in water. A whole range of colors and lusters can be achieved by the use of different glaze colorants and smoking materials. The entire process takes minutes so that the strength and grace of the clay can be fully appreciated. The spontaneity of the firing is its beauty. The copper glazes are evanescent. The luster may be regained using a copper cleaner. The crackle glaze will not change over time.
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