Describes a method for assessing the degree of rusting of coatings by comparison with pictorial standards. The pictorial standards provided in this part of SANS 4628 show coated steel surfaces which have deteriorated to different degrees by a combination of rust broken through the coating and visible underrust. SANS 4628-1 defines the system for designating the quantity and size of defects and the intensity of changes in appearance of coatings and outlines the general principles of the system. This system is intended to be used, in particular, for defects caused by ageing and weathering, and for uniform changes such as colour changes, for example yellowing.