Stoneware clays differ from porcelain due to the small quantities of iron and other impurities in the clay to give it color and to reduce it’s firing range. Most stoneware clays contain grog to give it strength and make it more versatile in its plastic state. I like to use soldate clay body because of the light tan color of the clay and the effects it has on the glazes in reduction (firing without oxygen). I also use this clay for all my Raku pieces because the clay can absorb the thermal shock it undergoes in the Raku firing process.