Bentonite definition

Bentonite is a type of clay that is created from airborne volcanic ash.  The clay must be combined with another type of clay due to its shrinkage being very high.  It is characterized by very fine particles and is very plastic.  If one adds 2-3% to clay it will raise the level of plasticity.  Bentonite is combined with a glaze in order to maintain suspension and enhance the raw glaze adhesion.