The condition of the coating deteriorates during operation. For this purpose, a visual inspection is carried out to determine the amount, intensity and extent of damage as well as changes in the appearance of the coating.
The evaluation method is also used after artificial aging carried out under laboratory conditions.
The main defects to be inspected are blistering (ISO 4628-2), corrosion (ISO 4628-3), cracking (ISO 4628-4), flaking (ISO 4628-5), filiform corrosion (ISO 4628-10) as well as corrosion in the cut (ISO 4628-8). The degree of damage to the coating is expressed on a five-point scale and depends on the density and size of changes on the test surface. In addition to the above defects, changes in the appearance of the surface, such as yellowing, discoloration, are also reported.