The origins of Raku can be traced back hundreds of years to Japan, where it was used as the traditional method of creating clay bowls for the tea ceremony. Over the years potters have embraced and adapted the methods, celebrating the remarkable but unpredictable results achieved using raku techniques.
The glazed pots are fast fired for 30 or 40 minutes up to temperatures between 850c and 1040c depending on the glaze and removed from the fire red hot. They are then placed in a reduction atmosphere containing combustible materials (sawdust, shavings, and dry organic materials such as seaweed, straw, plants or newspaper). The hot pot sets fire to the material and for a few seconds the flames are permitted to play on the piece causing changes in the glazes. Then an airtight lid is placed over all and left for a period to absorb the carbon from the smoke. In this fast cooling process the glazes may crackle and the cracks in the glaze allow in the carbon creating a random network pattern in the exposed clay. Control of this effect can be further obtained by masking techniques.
The pot is finally dunked in cold water and this shock will also affect the finish. Raku requires a clay that can withstand thermal shock. The pot is cleaned of surplus carbon and the potter discovers what the raku process has offered up. Joy, revelation, satisfaction, disappointment, back to the drawing board, are among the emotions that can ensue.
Raku is a dynamic and addictive process. No two pieces are the same,
each unique and unrepeatable. A glaze might be the same formula but each firing, each potter, will reap a different reward from the fire.