Feldspar Digitalfire
Feldspar melts by itself to be a glaze, but crazes badly. Pure MinSpar feldspar fired at cone 6 on Plainsman M370 porcelain. Although it is melting, the crazing is extreme! And expected. Feldspars contain a high percentage of K 2 O and Na 2 O (KNaO), these two oxides have the highest thermal expansion of any other oxide.