ISO 19403-5:2017 specifies a test method to determine the polar and dispersive fractions of the surface tension of liquids by optical methods. The method can be applied for the characterization of liquid coating materials.
The applicability can be restricted for liquids with non-Newtonian rheology[1].
ISO 19403-5:2017 assumes that the information of surface tension of the liquid to be tested and the surface free energy of the dispersive reference solids is known.

[1] This term is defined in DIN 1342-1.