Coatings Technology Handbook P02

The shear viscosity is defined as the ratio of the shear to the shear strain rate, at the strain rate of interest. Although the viscosity is usually quoted as a number without reference to the strain rate, it is really a function of strain rate. The strain rate dependence and, in certain situations, the time dependence, of the viscosity need to be determined if a meaningful correlation is to be made with coating phenomena.