Overview
ISO 15496:2018 - Textiles - Measurement of water vapour permeability of textiles for the purpose of quality control - defines a comparatively simple, reproducible laboratory method to measure water vapour permeability of textile materials for in-plant quality control. The standard describes the apparatus, specimen preparation, test procedure and calculation needed to obtain a water-vapour-permeability value useful for manufacturing control. It explicitly notes limitations: it is not suitable for classifying physiological water-vapour resistance (e.g., for personal protective equipment) and results are not directly comparable with other “dry desiccant” cup methods (see Annex C).
Key topics and technical requirements
- Test principle: A textile specimen is mounted on a ring holder with a waterproof, microporous hydrophobic membrane and equilibrated over water. A measuring cup filled with saturated potassium acetate solution (creates ~23% RH at 23 °C) is inverted over the specimen; change in cup mass over the test period quantifies vapour transfer. Apparatus correction (membrane-only control) is required.
- Apparatus essentials: membrane (high vapour permeability), specimen holder, support frame, water bath maintained at (23.0 ± 0.1) °C, measuring cup (85–95 mm ID), precision balance (±1 mg), and potassium acetate solution prepared per ISO 3696 water quality guidance (100 g potassium acetate : 31 g water).
- Specimen & timing: three circular specimens (~180 mm diameter), membrane covers ~200 mm; immersion equilibration ~15 min; measuring cup on specimen for 15 min ±10 s.
- Calculations & correction: water vapour permeability (μWV) is calculated from mass change, area, partial vapour pressure difference and time, with correction for apparatus permeability (membrane-only measurement).
- Precision: inter-laboratory repeatability and reproducibility reported (e.g., standard deviations ≈ 0.007 and 0.011 for tested fabrics).
Practical applications and users
ISO 15496:2018 is intended for:
- Textile manufacturers and production quality control teams monitoring batch uniformity and process stability.
- Internal laboratory technicians and QC labs performing routine permeability checks on fabrics, laminates and coated textiles.
- Suppliers and converters who require a standardized, fast method for comparing material lots within the factory environment.
It is not intended as the definitive physiological comfort or PPE performance test - for those applications, use more comprehensive standards.
Related standards
- ISO 11092 - more comprehensive method for evaluating water vapour resistance and physiological relevance (comfort/PPE applications).
- ISO 3696 - specification for water for analytical laboratory use (referenced for potassium acetate solution preparation).
- Note: ISO 15496 results are not directly comparable with other dry desiccant cup methods; see Annex C for explanations.
Keywords: ISO 15496:2018, water vapour permeability, textiles, quality control, textile testing, potassium acetate, membrane, water bath, ISO 11092, desiccant cup methods.