I use white clay, which I burn at 950oC and sometimes I glaze the goods, then at 1050oC.
Low burning clay must be glazed to become waterproof.
I burn raku at 850-950oC in a gas-fired oven outdoors. I lift out the glowing goods and place them in a container of combustible material for reduction.The crackling of the glaze occurs as the temperature changes rapidly.