PFAS Restrictions Rewriting Water Repellent Specifications Mid Season
Mid-season PFAS spec changes require re-engineering fabric density, adjusting curing parameters, and holding lot-traceable total fluorine CIC test evidence.
ISO 4920
Spray Assessment
Standardized laboratory testing determines the resistance of fabrics to surface wetting by water. The procedure outlined in ISO 4920 uses a spray test to evaluate the performance of hydrophobic finishes on woven and knitted apparel. It provides a quick and repeatable visual rating system for quality control in textile mills.
Test Procedure
Standard apparatus delivers a controlled spray of distilled water onto a fabric specimen held at a forty-five degree angle. In ISO 4920, a specific volume of water is allowed to flow through a nozzle from a fixed height to simulate rainfall. The technician tap-drops the specimen frame to remove excess water before evaluation.
Visual Rating
Photographic and descriptive standards are used to assign a rating from one to five to the tested fabric. Under ISO 4920, a rating of five indicates that no water has stuck to the surface, while a rating of one shows complete wetting of the entire fabric face. This visual assessment helps in identifying uneven chemical application or insufficient curing of the durable water repellent finish.
It requires a highly trained eye to differentiate between adjacent rating steps on textured or woven fabrics.
Sourcing Criteria
Performance specifications for sportswear and outerwear require a high spray rating to ensure protection from light rain. Passing ISO 4920 indicates that the textile has a high barrier against moisture, which prevents it from becoming heavy and cold. It is the primary test used by brands before doing more expensive waterproof testing.