Overview
EN ISO 17872:2019 - Paints and varnishes: Guidelines for the introduction of scribe marks through coatings on metallic panels for corrosion testing - provides practical guidance on how to produce reproducible scribe marks through coating systems on metallic test panels. Prepared by ISO/TC 35 and adopted by CEN, this document applies to coatings with a dry film thickness < 500 μm and covers metallic substrates including steel, galvanized steel, aluminium alloys and magnesium alloys. It is a guideline based on a collaborative trial (no subsequent corrosion testing was used to validate the scribes).
Key topics and technical requirements
- Scope and applicability: Scribing methods for coated metal test-pieces (excludes electroplated metal and clad aluminium panels).
- Scribe geometry: Acceptable cross-sections include V- and U-shaped cuts (with dimensional relationships such as a > b > c for V-shape and b > 0.2 mm for both shapes), plus L-shaped, diagonal and rectangular variations illustrated in the standard.
- Typical dimensions: Recommended scribe lengths are generally in the 50–70 mm range to exceed expected corrosion creep and to provide a representative view of coating performance.
- Tooling: Guidance on scribing tools (knife/blade types, pencil-type tools, milling cutters, ceramic knives, gravers) and their impact on cross-sectional shape, depth and exposed metal area.
- Orientation and reproducibility: The standard discusses how scribe orientation (horizontal, diagonal, vertical) and surface rolling/milling direction affect salt deposition and corrosion patterns-stress is placed on consistent, accurate scribing to ensure reproducible test outcomes.
- Special cases: For hot-dip galvanized steel, the scribe must penetrate the coating and the metal layer into the steel substrate per ISO 12944 requirements.
- Test procedure elements: Apparatus, test panels, scribing procedure, verification of the scribing tool and required reporting are included; Annexes give tool examples and show how different scribing tools can produce differing corrosion test results.
Applications and users
Who uses EN ISO 17872:2019:
- Corrosion and coating test laboratories conducting salt-spray and other exposure tests
- Quality control teams in paint, coating and metal finishing industries
- Coating formulators and materials engineers developing and validating protective systems
- Certification bodies and standards committees aligning test methods
Practical uses include accelerated corrosion tests, comparative product evaluation, production QC and failure-analysis preparation.
Related standards
Keywords: EN ISO 17872:2019, scribe marks, corrosion testing, paints and varnishes, metallic panels, coating scribing, dry film thickness, salt-spray testing.
