ISO 4628-2-2016 pdf free.Paints and varnishes – Evaluation of degradation of coatings一 Designation of quantity and size of defects, and of intensity of uniform changes in appearance Part 2: Assessment of degree of blistering.
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 illustrate 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 — Lighting and procedure for visual assessments 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 Si size of blisters is not visible with normal corrected vision but only with 10 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 illumination. 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 AnnexA.ISO 4628-2 pdf free download.