I'm asked all the time why I don't use the white and rust Alabama "clay" one often sees in souvenir shops. That is a liquid slip poured into a mold (ceramic) and fired at a low temperature. I use a commercial stoneware clay, and commercial glazes, which fire to cone 6 (over 2000 degrees) in the kiln. These clays are consistently dependable, and are oven, microwave, and dishwasher safe, while ceramic ware is not.
After years of admiring and purchasing stoneware pottery, I decided to make my own. I began throwing functional ware in 2012, and offering my crafts for sale the next year. Using only food safe glazes, all my items are oven safe, microwave safe, and dishwasher safe.