n The correction factor derived by B. Rabinowitsch (1929) applied to the Newtonian shear rate at the wall of a circular tube (including capillary) through which a non-Newtonian liquid is flowing, gives the true shear rate at the wall. For pseudoplastic liquids such as paints and some polymer melts the correction is always an increase. If the fluid obeys the Power Law it reduces to a simple correction factor (3n + 1)/4n, where n is the flow-behavior index of the liquid (Munson BR, Young DF, Okiishi TH (2005) Fundamentals of fluid mechanics. Wiley, New York; Harper CA (ed) (2002) Handbook of plastics, elastomers and composites, 4th edn. McGraw-Hill, New York; Patton TC (1964) Paint flow and pigment dispersion. Interscience Publishers, New York).