The characterisation of solid surfaces and liquids play a vital role in understanding adhesion, material wettability, biocompatibility, lubrication of solid surfaces as well as the wetting, spreading, washability and adsorption of liquids. Contact angle and interfacial tension measurement provide the information needed for the development and modification of liquid and solid surfaces.

The contact angle is the angle formed by a liquid at the three phase contact line where a liquid, gas and solid intersect. The shape of the drop is controlled by the three forces of interfacial tension. The contact angle is a quantitative measure of the wetting of a surface by a liquid or melt. It can as well be used as a control measure in surface treatment and cleanliness.