Most of the Calamityware pieces are porcelain but this cookie jar is stoneware. They are almost the same material both made from clay, fired at extremely high temperatures, fully vitrified and water tight. Stoneware is a heavier material, and more opaque. More important, in the kiln stoneware doesn’t shrink as much as porcelain so it’s a good choice for square shapes and shapes with tight-fitting lids. Like our porcelain, the cookie jar is food safe and dishwasher safe and contains no dangerous levels of lead or cadmium in the glazes. The workshop that will make these is highly regarded and supplies high-end retailers like Williams Sonoma and Pottery Barn.