Overview
ISO 2081:2025 - Metallic and other inorganic coatings - covers requirements for electroplated zinc coatings on iron and steel that receive supplementary treatments using chromium (VI) (hexavalent chromium). The standard specifies what purchasers must supply to electroplaters, appearance and thickness requirements, conversion and supplementary treatments, adhesion and corrosion-testing methods, and heat-treatment controls before and after electroplating. It applies to electroplated zinc used for protective and decorative purposes and excludes zinc applied to non‑fabricated sheet/strip/wire, close‑coiled springs, and non-protective uses.
Key topics and requirements
- Scope and exclusions: Defines applicability to iron and steel articles and notes limitations for threaded components (dimensional/fit constraints can limit coating thickness).
- Purchaser information: Lists essential data to be provided in orders/drawings - designation referencing ISO 2081, surface areas, finish (bright/dull), conversion treatment required, thickness and adhesion criteria, heat‑treatment needs, sampling and inspection rules.
- Designation system: Standardized notation for basis metal, stress‑relief and post‑plating heat treatments, undercoats (if any), zinc thickness, and type of chromium(VI) conversion or supplementary treatment.
- Appearance, thickness and adhesion: Requirements for finish quality, minimum coverage rules (areas accessible to a 20 mm ball), and adhesion testing procedures.
- Conversion and supplementary treatments: Chromium(VI) conversion coatings and other supplementary treatments (e.g., lacquers or organic seals) and codes for these treatments (Annex A).
- Corrosion and accelerated testing: Neutral salt spray testing (ISO 9227) and corrosion rating procedures (ISO 10289) referenced for performance verification.
- Hydrogen embrittlement and heat treatments: Stress‑relief heat treatments before processing and hydrogen‑embrittlement‑relief treatments after electroplating are required where applicable; relevant test methods and precautions are referenced.
- Sampling and measurement: Sampling by attributes (ISO 4519) and coating thickness measurement methods (ISO 1463, ISO 2177) are included.
Applications and users
ISO 2081:2025 is used by:
- Electroplating shops and coatings processors
- Purchasing engineers and specification writers
- Quality and inspection teams performing adhesion, thickness and corrosion tests
- Designers and manufacturers specifying protective and decorative zinc coatings on iron and steel components
It supports consistent specification and verification of electroplated zinc + chromium(VI) systems where corrosion protection and appearance are required.
Related standards
Key normative references and related documents include:
Note: ISO 2081:2025 includes a safety warning about health and environmental hazards associated with hexavalent chromium; regional regulations (e.g., REACH) can restrict its use and may require alternative conversion coatings.