Everything You Never Knew About Raku, and Didn't Know You Didn't Know:
- Raku is a Japanese form of pottery 15 generations old. The name means, "oh man, that's hot!"*
- Raku is made from porous clay that contains a lot of "grog", or pulverized previously-fired pieces. This grog helps the formed piece to withstand thermal shock.
- The clay is hand-shaped, fired in an electric kiln then glazed. Or not glazed -- these pieces are called "naked".
- The piece is set outdoors in a gas kiln. The temperature is quickly raised to 1,800 degrees Fahrenheit (in an hour). Thermal shock causes cracks in glassy glazes that have been applied.
- While the piece is still glowing molten orange, it is removed from the kiln and then sealed into a "reduction chamber" (aka "pressure cooker") filled with combustible materials like paper or sawdust. The combustibles immediately light, smoking and filling cracks in the glaze with carbon. Metallic glazes reduce, showing randomized colours which depend upon minute atmospheric details at the time of the firing.
* It actually means, "enjoyment", "comfort" or "ease". It's derived from the name Jurakudai, the palace in Kyoto where the art form developed. We think the name caught on so well because the kiln is raised to a relatively low temperature (as pottery goes), or maybe because the pieces were traditionally used in Japanese Tea ceremonies. Nowadays, Raku is a purely ornamental art form.