Almost any clay will work. A natural, locally found earthenware or stoneware clay (gumbo!) can be made shock resistant and workable by opening it up with sufficient additions of; fireclay and sand or grog. Probably the most important factor in the success of a raku clay body is the addition of the fore-mentioned materials. Addition of these materials produces the porous properties needed for rapid even drying of the greenware, as well as the rapid contraction of the ceramic object after the firing and during the cooling and reduction phase. Following is a group of raku clay bodies given in parts by weight.