n An instrument for measuring the viscosity of pourable liquids, slurries, plastisols, and solutions. Most are of the bob-and-cup type. In these, the bob is a polished, accurate cylinder that is immersed in the liquid contained in the cup. Either the bob or cup is rotated and the torque on one or the other is measured, as is the rotational velocity. From these and the dimensions, the viscosity can be inferred, either directly by calculation from principles or indirectly by calibration with standards of known viscosity. An instrument widely used in the plastics industry is the Brookfield Viscometer.