Overview - EN ISO 3613:2021 (Chromate conversion coatings)
EN ISO 3613:2021 (adopted by CEN) specifies standardized test methods for chromate conversion coatings applied to zinc, cadmium, aluminium‑zinc alloys (≈55 % Al) and zinc‑aluminium alloys (≈5 % Al). The standard covers detection and measurement of both colourless (thin) and coloured (thicker) chromate coatings, including the presence and quantity of hexavalent chromium (Cr(VI)), total chromium per unit area, coating mass per unit area, adhesion, and overall coating quality. This edition (2021) replaces the 2010 version and aligns certain analytical methods with related international guidance.
Key topics and technical requirements
- Detection of colourless chromate conversion coatings on zinc, cadmium and specified alloys (qualitative tests).
- Determination of hexavalent chromium (Cr(VI)) in both colourless and coloured chromate coatings - methods include non‑destructive and destructive test solution procedures (notably referred to as test solutions C1 and C2).
- Total chromium per unit area on zinc and cadmium surfaces (quantitative measurement).
- Mass per unit area of chromate coatings determined by gravimetric methods (referenced to ISO 3892).
- Adhesion testing by abrasion to assess satisfactory bond/performance of conversion coatings.
- Quality evaluation tests specific to chromate layers on zinc and cadmium surfaces.
- Analytical calibration requirements (e.g., spectrophotometer calibration) and blank/test controls to ensure reliable quantitative results.
- Applicability limited to chromate coatings free from supplementary topcoats (oils, polymers, waxes).
- Safety and regulatory context: chromate coatings contain Cr(VI); usage and testing are subject to health, safety and regulatory constraints (EU restrictions apply to Cr(VI)-containing products and processes).
Practical applications and who uses this standard
- Quality control and laboratory testing for galvanizers, plating shops and metal finishers applying chromate conversion coatings.
- Third‑party test laboratories verifying compliance with procurement specifications or regulatory requirements.
- Product engineers and corrosion protection specialists specifying and validating coating performance on fasteners, hardware, automotive and industrial components.
- Purchasing, inspection and certification bodies that require standardized, reproducible tests for coating presence, Cr(VI) content, coating mass and adhesion.
- Regulatory compliance teams monitoring Cr(VI) presence and ensuring correct labeling, documentation and substitution decisions.
Related standards
- ISO 3892 - Conversion coatings: gravimetric methods for coating mass per unit area
- ISO 4520 - Chromate conversion coatings on electroplated zinc and cadmium coatings
- IEC 62321-7-1 - Analytical method alignment referenced in this edition
- IEC 60068-2-30 - Environmental testing referenced in normative clauses
EN ISO 3613:2021 is essential for consistent, internationally recognized testing of chromate conversion coatings and for managing quality, safety and regulatory obligations related to chromium in surface treatments.
