NOTE 1 Pores are usually perpendicular to the coating surface but may be inclined to the coating surface. They are frequently cylindrical in shape but may also assume a twisted shape (see Annex C).

NOTE 2 Porosity may vary in size from the submicroscopic, invisible using a light microscope, to the microscopic, visible from × 10 to × 1 000, to the macroscopic, visible to the naked eye.

NOTE 3 Porosity may be visibly indicated by discolouration of the coated surface.

NOTE 4 Porosity in a coating is not always detrimental. In microdiscontinuous chromium, for example, porosity or microcracking is beneficial and tests are conducted to indicate the pores.

NOTE 5 Results obtained from porosity tests, expressed in terms such as pores per square centimeter, are relative values associated with the specific test method used and the magnification used during examination. Annex B gives typical report criteria.