ISO 4628-2:2016 download free.Paints and varnishes — Evaluation of degradation of coatings — Designation of quantity and size of defects, and of intensity of uniform changes in appearance — Part 2: Assessment of degree of blistering.
1 Scope
This part of ISO 4628 specifies a method for assessingthe 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 delects caused by ageing and weathering, and for unifnrm 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 Elgurel to Figure 4.
MOTE The 51 size otblisters is not visible with normal corrected vision but only with IO 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.
lithe assessment is to be done using an optical imaging system, calibrate the system using the images given in AnnezA.
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.
For example, if the coating Is assessed as having blisters quantity 2, sIze 2, i.e. matching Figiirel a), it shall be reported as
— blistering; degree of blistering 2(S2).
6 Test report
The test report shall contain at least the foliDwing Information:
a) all details necessary to identify the coating examined:
b) a reference to this part of ISO 4628. i.e. ISO 4628-2;
c) the type of surface examined, its size and. if appropriate. Its location;
d) the result of the evaluation as indicated in CLause 5:
e) an indication of the illumination under which the assessment was carried out:
f) any unusual features (anomalies) noted during the assessment
g) the date of the examination.