A Preface
ISO (International Organization for Standardization) is a global alliance of national standards bodies (ISO member bodies). The development of international standards is usually carried out through ISO technical committees. Each member institution interested in a subject on which a technical committee has been established has the right to be represented in the committee. Government and non-governmental international organizations that liaize with standardization organizations are also involved in this work. ISO works closely with the International Electrotechnical Commission (IEC) on all matters of electrical standardization.

International standards are drafted according to the rules given in Part 2 of the ISO/IEC Directive.

The main task of the technical committee is to develop international standards. Draft international standards adopted by the Technical Committee will be circulated to member bodies for voting. Publication as an international standard requires approval by at least 75% of member institutions.

Please note that certain contents of this document may be subject to patent rights. ISO is not responsible for identifying any or all such patent rights.

ISO 4628-8 was developed by Technical Committee ISO/TC 35, Paints and varnishes, Subcommittee SC 9, General test methods for paints and varnishes.

The second edition cancels and replaces the first edition (ISO 4628-8:2005). For this revision:

a) The use of measurements and calculations to determine delamination and corrosion is preferable to the use of graphical standards;

b) Introduce artificial defects whose shapes are not linear crossed marks.

ISO 4628 consists of the following sections under the general heading Paints and varnishments – Assessment of coating degradation – designation of the number and size of defects, and the intensity of uniform changes in appearance:

— Part 1: General introduction and specifying the system

— Part 2: Assessment of the degree of foaming

— Part 3: Assessment of the degree of rust

Part 4: Evaluation of the degree of cracking

— Part 5: Assessment of the degree of peeling

— Part 6: Assessing the degree of chalking by the tape method

— Part 7: Assessing the degree of chalking by the velvet method

— Part 8: Assessing the degree of delamination and corrosion around marking or other artificial defects

— Part 10: Assessment of the degree of filamentous corrosion

ISO 4628-8-2012 – Assessment of ageing of lacquers and varnish coatings – Assessment of the number and size of defects and the intensity of uniform changes in appearance – Part 8: Assessment of the degree of stripping and corrosion around scratches

Introduction
ISO 4628-1[1] defines a system for specifying the number and size of defects and the intensity of uniform variations in coating appearance and Outlines the general principles of this system. The system is particularly suitable for defects caused by aging and weathering, as well as uniform changes, such as color changes, such as yellowing.

Other parts of ISO 4628 provide graphical standards or other methods for assessing specific types of defects. Build on existing evaluation plans whenever possible.

After exposure to a coated test board with strewn or other artificial defects in a corrosive environment, one or a combination of the strewn or other artificial defects, the following phenomena may occur around the strewn or other artificial defects:

– stratification;

— Corrosion.

Delamination and corrosion or other man-made defects around the streamer will be evaluated separately to provide more detailed information about the performance of the coating system in a corrosive environment.

In addition to the procedures specified in this part of ISO 4628, it is possible to use optical image processing to evaluate delimitation and corrosion around scratches or other artificial defects.

The rating of other defects is described elsewhere in ISO 4628.

ISO 4628-8-2012 – Assessment of ageing of lacquers and varnish coatings – Assessment of the number and size of defects and the intensity of uniform changes in appearance – Part 8: Assessment of the degree of stripping and corrosion around scratches

1 Scope
This part of ISO 4628 specifies a method for assessing delamination and corrosion around strewn lines or other man-made defects on coated panels or other coated specimens caused by a corrosive environment.

This part of ISO 4628 does not include an assessment of pitting erosion or pit depth.

Note 1 Examples of corrosive environments are artificial atmoses such as salt spray used in the test method specified in ISO 9227 [7] and seawater immersion used in the test method specified in ISO 15711. [8] Natural environments can also be used.

Note 2 The extent of other defects can also be determined in conjunction with delamination and corrosion. The method is as follows:

– Foaming according to ISO 4628-2 standard; [2]

– rust according to ISO 4628-3; [3]

– cracking meets ISO 4628-4 standard; [4]

– peeling according to ISO 4628-5 standard; [5]

– Filamentation corrosion in accordance with ISO 4628-10 standard. [6]

2 Normative references
The following references are required for the application of this document. For dated references, only the cited version applies. For undated references, the new version of the reference (including any revisions) applies.

ISO 3270, Paints and varnishes and their raw materials – temperature and humidity regulated and tested

ISO 4628-8-2012 – Assessment of ageing of lacquers and varnish coatings – Assessment of the number and size of defects and the intensity of uniform changes in appearance – Part 8: Assessment of the degree of stripping and corrosion around scratches

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

3.1 Leakage coating

There is no paint film in some areas of the coated substrate

3.2 Artificial defects

By coating, it is deliberately introduced in order to expose the underlying metal substrate before exposure to a corrosive environment

3.3 Circular defect

By coating the circular holiday, deliberately introduced in order to expose the underlying metal substrate prior to exposure to the corrosive environment

3.4 Corrosion area

The area around the defect where the substrate is corroded

3.5 Layered Regions

The area around the defect where the coating loses adhesion to the substrate or the underlying coating

3.6 Scribes

Deliberately introduced through a linear leakage of the coating in order to expose the underlying metal substrate prior to exposure to a corrosive environment

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