Tuesday, August 09, 2011

Naked Raku


Naked Raku, also called slip resist, is a process in which the clay piece is ultimately glazed only with smoke, hence the name “Naked” because it has no glaze. Before the clay is completely dry the surface is burnished which results in a hard, smooth surface. The piece, after first being bisqued fired, is covered with a layer of slip, which is really only a thin mixture of clay and water. After that is thoroughly dry, a layer of glaze is added on top of the slip. The pot is then fired in a propane raku kiln to the temperature of about 1425 degree Fahrenheit.

Upon reaching that temperature, the pot is immediately pulled from the kiln with tongs and placed in a metal container (called a combustion bin) with sawdust sprinkled in the bottom. More sawdust is then sprinkled over the top and the piece bursts into flame. A tight fitting lid is then placed over the pot and it cools for about 12 minutes. Then it is pulled out of the combustion chamber and placed on the ground and sprayed with a fine mist of water. As it continues to cool, the glaze and slip layers fall away leaving smoke as the only decoration.

As the pot was cooling in the combustion bin the glaze began to crack. As the cooling process is taking place the oxygen in the container becomes thinner and the pot starts sucking in the smoke. Ultimately all the glaze and slip fall away and all the areas where the glaze cracked and all the areas where there was no glaze become black. Because I use thinner glaze layers then most artists, I am also able to achieve gray areas in which the black crackles also show through.--Jean Handley

(c) 2009 - Ruth Mitchell - all rights reserved

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