Overview
EN ISO 4920:2012 (ISO 4920:2012) specifies a standardized spray test to determine the resistance of textile fabrics to surface wetting by water. The method applies to any fabric, with or without a water‑resistant or water‑repellent finish. It is important to note that this test measures surface wetting only and is not intended to predict rain‑penetration or water passage through a fabric.
Key topics and technical requirements
- Test principle: A defined volume of distilled or de‑ionized water is sprayed onto a fabric specimen mounted on a ring inclined at 45°; the wetting appearance is compared with descriptive and photographic standards to assign a spray rating.
- Apparatus:
- Funnel (150 ± 5 mm diameter) and metal spray nozzle (19 holes, Ø 0.86 ± 0.05 mm).
- Specimen holder (ring/hoop) with test area centred 150 ± 2 mm below the nozzle.
- Flow control: (250 ± 2) ml water poured into the funnel, with a spray duration of 25–30 s.
- Specimens and conditioning:
- At least three specimens, each ≥ 180 mm square, taken from different parts of the fabric.
- Conditioning and testing atmospheres per ISO 139 (standard atmospheres) unless otherwise agreed.
- Water temperature reported (typical options: 20 ± 2 °C or 27 ± 2 °C).
- Procedure highlights:
- Mount specimen face up; warp/length direction parallel to water flow unless specified otherwise.
- After spraying, tap the holder and immediately rate the face of the specimen.
- Evaluation (spray rating scale 0–5):
- 0 = complete wetting of entire face; 5 = no sticking or wetting. Intermediate increments (0.5) allowed in some cases; photographic AATCC-based scale is provided.
- Reporting: Must include reference to the standard, atmosphere, water temperature, individual spray ratings, sample identification, and any deviations.
Applications
- Quality control and acceptance testing for water‑repellent finishes and coatings.
- Product specification and compliance checks for outerwear, technical textiles, upholstery and protective fabrics.
- R&D and comparative performance testing of treatments (DWR finishes) and fabric surface treatments.
- Supplier qualification and pre‑purchase testing where surface wetting behaviour is a product requirement.
Who uses this standard
- Textile manufacturers and finishers
- Independent testing laboratories and QA departments
- Apparel and outdoor product developers
- Procurement/specification engineers and compliance officers
Related standards
- ISO 139 - Standard atmospheres for conditioning and testing
- ISO 3696 - Water for analytical laboratory use (referenced)
- AATCC Test Method 22 - Water Repellency: Spray Test (comparative photographic scale)
Keywords: EN ISO 4920:2012, ISO 4920:2012, spray test, textile fabrics, surface wetting, spray rating, water repellency, water resistance.
