Assessment of degree of blistering

BS EN ISO 4628-2:2003 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 ap pearance- Part 2: Assessment of degree of blistering.
This part of ISO 4628 describes 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 referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 4628-1, Paints and varnishes — Evaluation of degradation of coatings — Designation of quantity and size of defects, and of intensity of uniform changes in appearance — Part 1: General introduction and designation system
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 using the pictures given in Figures 1 to 4.
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.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 Figures 1 to 4, together with the approximate dimensions of the area concerned, or its proportion of the total area, expressed as a percentage.
For example, if the coating is assessed as having blisters of quantity 2, size 2, i.e. matching Figure2a), it shall be reported as:
blistering; degree of blistering 2(S2).
6 Test report
The test report shall contain at least the following information:
a) all details necessary to identify the coating examined;
b) a reference to this part of ISO 4628 (ISO 4628-2:2003);
c) the type of surface examined, its size and, if appropriate, its location;
d) the result of the assessment in accordance with Clause 5;
e) an indication of the ilumination under which the assessment was carried out;
f) any unusual features (anomalies) noted during the assessment;
g) the date of the examination.BS EN ISO 4628-2 pdf free download.Assessment of degree of blistering