Description

Viscosity is a measure of the resistance of a fluid to deform under
shear stress. It is commonly perceived as flow behaviour or resistance
to pouring. Viscosity describes a fluids internal resistance to
flow and may be thought of as a measure of fluid friction.
Viscosity at final plays a key role in th processing stage!
For certain liquids viscosity is a material constant that only depends
on temperature and pressure. This group of materials is
termed Newtonian liquids.

Liquids which do not follow this proportional ratio are called non-
Newtonian.
In practice, time-dependent viscosity is called thixotropy. If a liquid
is sheared at a constant velocity gradient, viscosity will slowly
decrease. As soon as the shear forces are removed, viscosity will
recover and return to the initial value.