ABSTRACT
The wetting of solid substrates by liquids is a basic element in many natural and commercial processes, and its understanding has been the subject of intensive investigation over the past century. Some common examples include the spreading of liquid droplets on solids such as in the spraying of paint and agricultural chemicals, the penetration of ink in
implying hysteresis. Knowledge of contact-angle hysteresis is important, not only because it means that even for single-component liquids, a unique static contact angle may be difficult to obtain experimentally, but also because it determines the pressure required to dislodge a drop in a capillary, or the limits to the capillary driving force in wicking, or the maximum substrate tilt angle before a drop slides.
