Standards:ASTM D 2419, AASHTO T 176
Marsh Cone (Marsh Funnel) is used to find out viscosity of bentonite slurry and similar material. The marsh cone is 6 inch in diameter at the top and 12 inch long, and tapers to join a tube 2 inch long and 3/16 inch inside dia. The capacity of the funnel is 1500cc. Time in seconds required to flow out 1000cc of slurry from cone is measured as funnel viscosity of the material.
Marsh Funnel Viscosity Test is the most preferred test to measure the viscosity of drilling fluid. Please watch the below video for an easy demonstration of Viscosity test using Marsh Funnel.