ISO 4628-2:2016 pdf free

ISO 4628-2:2016 pdf free.Paints and varnishes – Evaluation of degradation of coatings
This part of ISO 4628 specifies a method for assessing the degree of blistering of coatings by comparison with pictorial standards.
The pictorial standards provided in this part of ISO 4628 ilustrate blisters in the sizes 2, 3, 4, and 5, and each size in the quantities (densities) 2, 3, 4, and 5.
ISO 4628-1 defines the system used 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.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 13076, Paints and varnishes一Lighting and procedure for visual asessments of coatings
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 degree of blistering
rating characterizing blisters in a coating in terms of quantity (density) and size
4 Assessment
Assess the quantity and size of the blisters in a coating by means of the pictures given in Figure 1 to Figure 4.
NOTE The S1 size of blisters is not visible with normal corrected vision but only with x10 magnification.
Where the area to be examined exhibits blisters of varying size, quote as the size rating that of the blisters which are typical of the test area.
Carry out the assessment under good ilumination, as specified in ISO 13076.
If the assessment is to be done using an optical imaging system, calibrate the system using the images given in Annex A.
5 Expression of results
Express the ratings for the quantity (density) and size of the blisters as given in Figure 1 to Figure 4, together with the approximate dimensions of the area concerned, or its portion of the total area, expressed as a percentage.ISO 4628-2 pdf download.