What is Water Permeability (Waterproof) of Fabrics

The permeability of a fabric is the ability that liquid water to penetrate from one side of the fabric to the other side. The wettability of the fabric surface, the coating of the fabric and the temperature and humidity of the environment are the main factors affecting the water permeability of the fabric. In order to express the water permeability of fabrics with different requirement, we need to test the water permeability of fabrics in different ways for different waterproof and water permeable requirements of fabrics in different industries.

Test Method for Permeability (Rainproof) of Fabrics

Different methods are used to test the water permeability or waterproofing according to the actual use of fabrics, and various indexes are used to express the water permeability or waterproof of fabrics.

Common test methods include hydrostatic pressure method, spray method, rain method, and wicking method. The rain test is to test the waterproof by simulating the fabrics exposed to air in heavy rain, which is suitable for any fabric with or without waterproof treatment. The principle is to use the test sample to wrap the weighing absorbent paper and then weigh the absorbent paper again after the test. The weight difference between the two times of the absorbent paper is the water permeability of the sample.

Rainproof Tester by Rain Method

Rain Tester is to determine the penetration resistance of fabrics or composites at different intensities of water impact. It can simulate that rain horizontally impacts fabric samples mounted vertically in a stainless steel bath. Samples are backed with a standardized blotting paper which is weighed before and after each test. The rain is formed by a column of water which can be adjusted from 600mm (24 in.) to 2400mm (96 in.) with an increment of 300mm (12 in.) increments, applied via a standardized nozzle. After spraying with water for 5 minutes under the control conditions, the water permeability of the sample can be determined during the test process by reweighing the absorbent paper again.