3. Adhesion

Most coatings are applied for a specific purpose, such as decoration or corrosion protection. For this purpose to be achieved, the coating must adhere well to the substrate. Adhesion is a measure of both the quality of the preparation of the surfaces to be coated and the quality of the coating operation.

Perfect adhesion exists insofar as the bonding force between the coating and the substrate is greater than the inherent resistance (tensile strength, for example) of each of them. The aim of the adhesion test is therefore to identify cases of imperfect adhesion.