ISO 21227-4-2008 Paints and varnishes – Assessment of defects on coated surfaces using optical imaging – Part 4: Assessment of filamentous corrosion

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ISO 21227-4 was prepared by the Technical Committee Subcommittee ISO/TC 35 (Paints and varnishes), SC 9 (General test methods for paints and varnishes) in cooperation with the Technical Committee CEN/TC 139 (Paints and Varnishes).

ISO 21227 consists of the following parts under the general heading Paints and Varnishes – Assessment of Defects on coated Surfaces Using optical Imaging:

— Part 1: General guidance

— Part 2: Evaluation procedure for multiple impact lithotripsy tests

— Part 3: Assessment of delamination and corrosion around lines

— Part 4: Evaluation of filamentous corrosion

ISO 21227-4-2008 Paints and varnishes – Assessment of defects on coated surfaces using optical imaging – Part 4: Assessment of filamentous corrosion

Traditional ISO testing methods used to assess surface defects and appearance changes typically use graphic standards that depict specific types of surface deterioration and require human visual evaluation. Compared with human visual assessment techniques, the techniques described in the various sections of this standard can produce more objective, accurate, quantitative and repeatable results.

1 range
This section of ISO 21227 describes a method for evaluating filamentous corrosion by digital optical imaging. Filamentous corrosion may be performed according to ISO 4623-1, ISO 4623-2 or EN 3665.

2 Normative references

The following references are required for the use of this document. For dated references, citation-only versions apply. For undated references, the latest version of the reference (including any revisions) applies.

ISO 4623-1, Paints and varnishes – Determination of filamentous corrosion – Part 1: Steel substrates

ISO 4623-2, Paints and varnishes – Determination of filamentous corrosivity – Part 2: Aluminium substrates

ISO 21227-1, Paints and varnishes – Assessment of defects on coated surfaces using optical imaging – Part 1: General guidance

Aerospace series – Paints and varnishes – Test methods – Filament resistance to corrosion of aluminium alloys – EN 3665

3 Terms and Definitions
For the purposes of this document, the terms and definitions set forth in ISO 21227-1 and below apply.

3.1 Filamentary corrosion

Type of corrosion in the form of filaments under paint, varnish, or a related product coating, usually starting with a bare edge or local damage to the coating

Note 1: Usually, filaments are irregular in length and direction of growth, but they may also be almost parallel and roughly equal in length.

Note 2 Filamentous corrosion may also occur under other protective coatings.

[Source: ISO 4623-1]

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