Overview
ISO 6270-2:2025 - "Paints and varnishes - Determination of resistance to humidity - Part 2: Condensation (in-cabinet exposure with heated water reservoir)" defines a reproducible method for exposing coated test specimens to condensation-water atmospheres in a climatic cabinet with a heated water reservoir. The standard sets general conditions and procedures for creating constant or alternating condensation atmospheres so that results from different laboratories are comparable. It does not specify specimen shape, preparation, test duration or assessment criteria.
Key topics and technical requirements
- Test atmospheres: Four principal atmosphere codes are specified:
- CH - Constant-humidity condensation (approx. 100 % RH on specimens).
- AHT - Alternating humidity and air temperature.
- AT - Alternating air temperature (with condensation periods).
- IC - Intermittent condensation (includes cooler periods; example: 40 ±3 °C warm period and cooling to ~23 ±5 °C, 50 ±20 % RH).
- Temperature control: Working chamber atmospheric temperature during condensation is (40 ± 3) °C (set point).
- Cycle timing: A 24-hour cycle is the general rule for alternating atmospheres; shorter cycles (12 h or 16 h) may be used by agreement.
- Apparatus requirements:
- A vapour-tight climatic chamber (except for controlled ventilation) with corrosion-resistant inner walls.
- A heated water reservoir / floor trough that generates the condensation; chamber heating is normally by heating the water, with supplemental heating allowed if needed.
- Provisions for specimen accommodation, chamber ventilation and loading; spacing recommendations aim to ensure uniform condensation.
- Reproducibility focus: Procedures ensure consistency across labs. The standard also notes that condensate may contain dissolved coating constituents or corrosion products, which can influence results.
- Limits: Users may agree on alternative parameters but must report deviations.
Applications and users
ISO 6270-2:2025 is used for accelerated humidity/condensation exposure testing of paint and varnish systems to assess susceptibility to humid environments and possible coating defects. Typical users:
- Paint, varnish and coatings manufacturers (R&D and QC)
- Independent test laboratories and certification bodies
- Automotive, aerospace, marine and industrial OEMs specifying corrosion/paint durability
- Specification writers and procurement engineers requiring standardized test methods
Practical uses include comparative performance testing of coating formulations, quality control sampling, and R&D screening for humidity resistance and condensation-related failure modes.
Related standards
- ISO 3270 - Temperatures and humidities for conditioning and testing
- ISO 4618 - Paints and varnishes - Vocabulary
- ISO 6270 series (other parts) and the ISO 4628 series (for post-exposure defect assessment) are commonly referenced alongside ISO 6270-2.