Contact angle measurement is a fast method for investigating the wettability of a specimen. It is possible to determine the hydrophilic properties of a solid surface using small drops of liquid (e.g. water).
In order to determine the contact angle, a tangent is applied at the point where the drop of liquid touches the solid surface and the ambient phase (air) (see diagram).
In order to calculate surface energies of the solid using different methods, comparison of the contact angle of at least two different liquids with known surface tensions is required.