By permission, Georgie's mixes Robert Piepenburg's Raku Clay formula. This clay utilizes kyanite as a grog and filler. Kyanite expands during the firing, knitting the clay together with a network of needle-like crystals, enabling you to throw and construct larger forms with fewer losses to thermal shock.
We host several Raku Party Firing events per year at Mondaes in Idaho, and have seen pieces make it through the process made of any low fire to high fire clay that has any amount of grog which helps with shock. We even Raku our poured low-fire ceramic pieces! To create high quality repeatable results, Piepenburg is our go-to Raku clay of choice.