Overview
ISO 21232:2018 specifies a laboratory test method to assess the moisturizing effect of textile materials by simulating the microclimate between textiles and human skin. Using a sweating guarded-hotplate (per ISO 11092) plus a purpose-built spacing device and humidity sensor, the method measures water‑vapour resistance including the air layer (Ret_al) and relative humidity (RH) in the air gap between a simulated skin surface and the specimen. The procedure applies to fabrics, films, coatings, leather and multilayer assemblies used in clothing systems.
Key Topics and Technical Requirements
- Principle: Simulate the skin–textile microclimate to evaluate how textiles retain or impede moisture evaporation and therefore influence skin hydration.
- Primary measurements:
- Water‑vapour resistance including air layer (Ret_al) - expressed in m²·Pa·W⁻¹.
- Relative humidity (RH) within the microclimate.
- Hydration value of the non‑porous hydrophilic membrane (measured by hydrometer/Corneometer® method) used to simulate skin moisture.
- Apparatus:
- Sweating guarded-hotplate conforming to ISO 11092:2014.
- Device including a temperature and humidity sensor positioned between hotplate and specimen; sensor accuracy ±2% RH, ±1 °C.
- Non‑porous hydrophilic breathable membrane (≈10–30 µm thick) with a hydration value of 45 ± 5.
- Test conditions and specimen preparation:
- Condition specimens at (20 ± 2) °C and (65 ± 4) % RH according to ISO 139.
- Test environment: measuring unit and air at 35 °C, ambient RH 40 %, air speed ≈1 m/s.
- Mount specimens over the membrane using the specified frame and magnets; wait for steady‑state readings.
- Reporting: Results must include specimen identification, number of specimens, conditioning atmosphere, average and coefficient of variation for Ret_al and RH, and any deviations from the procedure.
Applications and Who Uses ISO 21232:2018
- Textile manufacturers and R&D teams evaluating functional finishes (e.g., moisturizing finishes, encapsulated actives).
- Apparel designers for performance clothing (sportswear, thermal garments) where skin comfort and moisture balance are critical.
- Medical and cosmetic textile developers assessing materials intended to influence skin hydration.
- Independent test laboratories and certification bodies performing standardized comfort and moisturizing claims verification.
- Useful for substantiating product claims related to moisture retention, skin hydration potential, and microclimate comfort.
Related Standards
- ISO 11092:2014 - Textiles - Physiological effects - Measurement using sweating guarded-hotplate.
- ISO 139 - Textiles - Standard atmospheres for conditioning and testing.
Keywords: ISO 21232:2018, moisturizing effect, textiles, sweating guarded hotplate, microclimate, water‑vapour resistance, Ret_al, relative humidity, hydration value, textile testing.
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