Overview
ISO 9865:1991 is an international standard established by the International Organization for Standardization (ISO) for evaluating the water repellency of textile fabrics. This standard describes the Bundesmann rain-shower test, a controlled and reproducible method to assess how well textile fabrics resist water absorption when exposed to an artificial rain shower. It covers all essential aspects including test specimen preparation, apparatus specifications, testing procedure, result expression, and reporting guidelines.
Water repellency is critical for various textile applications, particularly in outdoor wear, upholstery, and technical textiles. ISO 9865:1991 helps manufacturers, researchers, and quality control laboratories ensure the effectiveness of water-repellent finishes applied to fabrics.
Key Topics
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Test Principle
The fabrics are mounted on specially designed cups and subjected to an artificial rain shower under controlled environmental conditions. Water repellency is visually assessed against reference photographs and quantified by measuring water absorbed and water penetrating through the fabric.
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Apparatus Requirements
The test utilizes a rain shower system producing 4 mm diameter water drops at a flow rate of approximately 100 ml/min per 100 cm², falling from a 1500 mm height. The system includes a clamping device shaped like a cup to hold fabric samples, a centrifuge to remove excess water, and a wiper assembly to simulate runoff.
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Conditioning Atmosphere
Test specimens are conditioned and tested in standard atmospheres as per ISO 139, maintaining relative humidity at 65±2% and temperatures either at 20±2°C or 27±2°C (for tropical conditions).
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Specimen Preparation and Testing Procedure
Circular specimens of 140 mm diameter are cut from the fabric, avoiding sample edges to ensure uniformity. After conditioning, specimens are exposed to the rain shower for 10 minutes while rotating to guarantee even water exposure. Post exposure, fabrics are centrifuged to remove excess water, then weighed to determine water absorption.
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Result Expression and Grading
Water absorption is expressed as a percentage by mass difference before and after testing. Water repellency is visually graded from 1 to 5 based on droplet behavior and wetting extent:
- Grade 5: Fast runoff of small drops
- Grade 4: Formation of large drops
- Grade 3: Drops adhere to parts of the fabric
- Grade 2: Partially wetted specimen
- Grade 1: Specimen wet through completely
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Test Report Content
Reports must include details such as standard reference, fabric characteristics, equipment used, test conditions (temperature, water hardness, pH), exposure times, weight changes, visual grades, water penetration values, and any observations.
Applications
ISO 9865:1991 serves as a valuable tool for textile manufacturers, finishers, and quality assurance labs to:
- Evaluate water-repellent finishes on fabrics used in outerwear, rainwear, tents, and upholstery.
- Develop and improve functional textile treatments that enhance weather resistance.
- Ensure compliance with product specifications and confirm performance consistency of water-repellent textiles.
- Support research and product development by providing reliable, standard test data on fabric water repellency.
- Assist regulatory bodies and certification programs with a standardized method for water resistance claims.
By employing this test, businesses can confidently market water-repellent textiles backed by internationally recognized standards.
Related Standards
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ISO 139:1973 - Textiles – Standard atmospheres for conditioning and testing
Describes the specific temperature and humidity conditions under which textiles should be conditioned and tested, critical for consistency in ISO 9865 testing.
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ISO/TC 38 - Textiles Technical Committee
Oversees development and maintenance of various textile testing standards, including those related to water repellency and waterproofness.
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Other ISO standards on textile water resistance and waterproof testing methods may complement ISO 9865 depending on product requirements and testing scopes.
Keywords: ISO 9865, Bundesmann rain-shower test, textiles, water repellency test, fabric water absorption, textile water resistance, water-repellent finishes, textile conditioning, textile testing standard, rain shower apparatus, waterproof fabric testing.
