High Gelling Bentonite: Description & Applications an easy to mix, high yield sodium bentonite formulated to provide viscosity and fluid loss control in water based mud systems that meets HDD, Tunnel boring, and diaphragm wall drilling requirements. Provides quick viscosity and lubrication. Reduces fluid loss during excavations. Deposits thin filter cake on bore walls to improve borehole stability Aids hole cleaning High gelling strength Environmentally safe