Effects of paraffin coatings on the shearing properties of lactose

An annular shear cell has been employed to measure the shearing properties of lactose powder coated with up to 10(-4) mol g-1 of powder of a series of paraffin hydrocarbons. The angle of internal friction, delta, of the coated powders was independent of their packing density. The shearing properties of the powders depended on the concentration, the viscosity and thickness of the coating material.