This is an expensive, quality bentonite! It is used in porcelains!

Monday 25th August 2014

HPM-20 micro-fine bentonite fired from cone 1 to 7 in oxidation. This bentonite is expensive compared to others and it used for the guarantee that there are no speck producing particles. However it is still high in soluble salts (that melt by cone 4) and is very dark burning in color. It is not unusual to put 3-5% of this (and other dirtier bentonites) into Grolleg porcelain bodies (where whiteness is supposedly important).

Pages that reference this post in the Digitalfire Reference Database:

Grolleg Kaolin, HPM-20 Volclay Bentonite, Bentonite, Efflorescence

This post is one of thousands found in the Digitalfire Reference Database. Most are part of a timeline maintained by Tony Hansen. You can search that timeline on the home page of