These bars are made for the SHAB test. The top one is cone 10 Reduction. Below that, cone 10 down to 5. The clay has been ground to 42 mesh. Notice that in reduction firing (top bar) there are almost no iron specks! And it has fired dense, to a porosity below 0.5%. At cone 10 oxidation the porosity is 0.8%. Drying shrinkage is between 5 and 5.5%. Fired shrinkage at cone 10 is less than 7%. At cone 7 it is a stoneware, having only 6% firing shrinkage and 3% porosity. This data is amazing because it is an unprocessed clay, merely ground in a hammermill to break up the lumps.
Plainsman 3D, Mother Nature's Porcelain/Stoneware