Much effort is expended at Plainsman Clays to develop good transparent base glazes. Far left is a white cone 6 porcelain made from New Zealand kaolin, a super-white-burning bentonite, feldspar and silica. P300 is a kaolin-only cone 6 whiteware. M370 is a kaolin-ball clay whiteware. The P300 and M370 recipes contain feldspar, silica and bentonite also. M340 is a buff stoneware, it is made from locally mined stoneware clays with no additions of feldspar or silica or any refined clays.
A type of stoneware made using locally mined materials or refined materials sufficiently high in iron to fire buff rather than white in color
Tony Hansen is the author of Digitalfire Insight, Digitalfire Reference Library and Insight-Live.com, he is a long-time potter, ceramic lab-technician and body and glaze developer.