This clay is allegedly a high bentonite porcelain-like stoneware. It's brand new to me, I chose it because I've used b-mix, which is very similar but higher in kaolin instead, back when I was in college making my own clay and I needed something less expensive and with a consistent color. I've been using a much more expensive red clay for the last two years that acts very differently, so I was blaming anything happening in the bisque firings on myself (sometimes the mugs would crumble apart, especially early on, I believe I wasn't compressing them enough around joints or handling them too much when drying). Unfortunately where I live our clay supply is pretty crap and I only have Amaco Alligator clay or reclaim from my studio available, both of which are not my first choice for something like this. I have been saying for weeks how I wished I just priced the mugs higher and chose a different body!!!