American Ceramic Supply Co. offers Cone 6 Stoneware Bisque. This high fire clay body is soft fired to a Cone 03 and ships by the case lot. Use Cone 5 or Cone 6 high fire glazes, such as Mayco’s Stoneware Glazes or Amaco high fire glazes - and fire to a Cone 5 or Cone 6. Cone 6 firings will provide for the most mature clay body that can be used in microwave and dishwasher. For oven use, we recommend placing the finished piece in a cold oven, allowing it to slowly warm as the over preheats. We advise against sudden temperature changes to avoid thermal shock - such as freezer to oven or vice versa.
Note the difference between Cone 06 - around 1835 degrees - and Cone 6 - around 2200 degrees. Low fire clay bodies are typically glazed all over and stilts are used when firing. High fire clay bodies, when firing to Cone 6, are typically not painted on the bottom, but dry footed and the piece is set directly on a well kiln washed shelf during firing to maturity.