The most common type of non-Newtonian behavior is shear thinning or pseudoplastic flow, where the fluid viscosity decreases with increasing shear. At low enough shear rates, shear thinning fluids will show a constant viscosity value, η0, termed the zero-shear viscosity or zero- shear viscosity plateau. At a critical shear rate or shear stress, a large drop in viscosity is observed which signifies the beginning of the shear thinning region. At very high shear rates, a second constant viscosity plateau is observed, called the infinite shear viscosity plateau. This is given the symbol η∞ and can be several orders of magnitude lower than η0 depending on the degree of shear thinning.