Wetting test

A coating, for example by glue or painting only adheres properly to a surface, if the coating substance wets the surface in its liquid phase. Wetting may be prevented by contamination of the surfaces specifically with oil, grease or waxes or by a low surface energy of the substrate material itself.

Wetting of a surface can be tested by use of test fluids (test inks) with a calibrated surface tension.

Another methode to test the surface energy is measuring the contact angle of a liquid drop deposited onto the surface.

Test fluids
The surface energy can be easily determined by calibrated test inks.