Feldspar

A feldspar is called 'potash' if there is more sodium than potassium.There are no real deposits that have the theoretical 17% KO, none are even close to tis , they have a mix of potassium and sodium. Glazes high in feldspar (35% or more) are likely to produce crazing problems. Flux saturated glazes with more that 50% feldspar may be unbalanced and lack adequate glass former or alumina.