ISO 4628-7:2003

Paints and varnishes — Evaluation of degradation of coatings — Designation of quantity and size of defects, and of intensity of uniform changes in appearance — Part 7: Assessment of degree of chalking by velvet method

Scope

ISO 4628-7:2003 describes a method suitable, in particular, for rating the degree of chalking on white or coloured exterior coatings and coating systems on rough surfaces (i.e. those having a roughness greater than segment 4 of reference comparator G as described in ISO 8503-1).
The test method specified may also be used for the assessment of the degree of chalking of coatings and coating systems on smooth surfaces, but the method specified in ISO 4628-6 is preferable for this purpose.
The test method is applicable to coatings and coating systems on mineral substrates, e.g. fibre cement, brick, concrete and renderings, independent of the structure of the surface. The method can be used quite effectively by experienced operators and is recommended for laboratory use as well as for on-site evaluation.