Videotutorial Water Repellency
The test for water-repellent properties of textiles determines how wet a textile becomes after being sprayed briefly with water. This simulates rain or spray. Water drops remaining on the textile affect the weight of the textile and may encourage water to penetrate the inside of the clothing.
Textiles that come into contact with spray water are tested - specifically water-repellent finishes, rain or outdoor clothing, tents, rucksacks, coverings for rain and sunshades and shower curtains and blinds. To assess the permanence of water-repellent characteristics in textiles, it is advisable to repeat the spray process before and after a care treatment.
The specification for the test of the water-repellent characteristics of textiles is the spray method as per DIN EN ISO 4920. However, this method only tests the water-repellent characteristics and not the resistance of the textile surface to penetration by rainwater. The samples are conditioned under normal climatic conditions of 20° Celsius and 65% relative air humidity as per DIN EN ISO 139. The test itself is carried out under the same standard conditions.
To test the textile surface, a sprinkling device or spray rating tester is used. The precision-machined nozzles distribute the spray water equally onto the sample which is fastened at a 45° angle and at a defined distance of 150mm to the sample under the spray nozzle. After spraying, the excess water is tapped off the measuring sample and evaluated. An assessment scale with the grades 0 (poor) to 5 (very good) is used. The grade is assigned using a photographic assessment scale or verbal description.
Textiles - determination of water-repellent characteristics (spray method) (ISO 4920:2012); German version EN ISO 4920:2012
DIN EN ISO 4920: 2012 12