Overview
ISO 11997-2:2025, "Paints and varnishes - Determination of resistance to cyclic corrosion conditions - Part 2: Wet (salt fog)/dry/humid/UV light," specifies a laboratory test method to evaluate the resistance of coatings to a defined cycle of salt fog, drying, high humidity/condensation and UV light. The method combines artificial weathering (UVA exposure and condensation) with cyclic salt spray/dry stages to simulate aggressive outdoor conditions in a reproducible way. It is the third edition and updates terms, lamp designations and normative references.
Key topics and technical requirements
- Test principle: Alternate exposure in an artificial weathering cabinet (UV + condensation) and a cyclic corrosion cabinet (salt fog/dry).
- Test cycle parameters:
- Artificial weathering: UVA 340 lamps, black panel temperature 60 °C, condensation in dark at 50 °C; cycle typically 4 h light / 4 h condensation.
- Cyclic corrosion cabinet: 60 min salt fog (ambient) / 60 min dry at (35 ± 2) °C; salt deposition 1–2 ml/h when collected over 24 h.
- Standard sequence: 168 h in the artificial weathering cabinet, then 168 h in the cyclic corrosion cabinet; repeat to a typical total of 1 008 h (6 weeks).
- Salt fog solution: Prepared from NaCl (0.50 ± 0.01 g/L) and (NH4)2SO4 (3.50 ± 0.01 g/L) using ISO 3696 water; purity limits for salts specified.
- Specimens and preparation:
- Burnished steel panels (min. 150 × 70 × 0.3 mm) per ISO 1514.
- Coating thickness measured per ISO 2808.
- Triplicate testing and inclusion of control specimens (recommended two controls).
- Evaluation and reporting:
- Examinations during dry phases and final assessment at end of last wet phase.
- Degradation assessed using established criteria (referenced ISO 4628 series for blistering, rusting, cracking, flaking, delamination, filiform corrosion).
- Requirements for sampling, conditioning and scribing are referenced to ISO 1513, ISO 3270, ISO 17872, ISO 15528.
Applications and who uses it
- Quality control and batch verification for industrial maintenance coatings, particularly for air-drying coatings on steel.
- Comparative performance testing in R&D for new coating formulations and systems.
- Independent laboratory testing for suppliers, OEMs, contractors and asset owners specifying corrosion resistance.
- Useful when reproducible, accelerated cyclic corrosion/UV exposure data are required for specification development, failure analysis or product benchmarking.
Related standards
Keywords: ISO 11997-2:2025, cyclic corrosion testing, salt fog, UV exposure, coating resistance, artificial weathering, paints and varnishes, cyclic corrosion cabinet, UVA 340.