3. Rain method:

The rain method is to test the water repellency of the fabric exposed to the air when simulating heavy rain. This method works for any fabric with or without a water-repellent finish.

Under the impact strength of water at different speeds, the impact water penetration resistance of single-layer fabrics or composite fabrics is measured. The test results are related to the water repellency of the fibers, yarns, and fabric structures in the fabric. The principle is to wrap the test sample in the weighed absorbent paper, and weigh the absorbent paper again after the test. The difference between the two weights is the water permeability of the sample. It is required that the quality difference of the absorbent paper before and after the test does not exceed 1g; if the quality difference is greater than 5g, it means that the fabric has poor water resistance.

In the experiment, the rain tester was used to test. The AATCC 35-2006 test method is to put a 15.2cm×15.2cm standard absorbent paper behind the sample, and weigh the standard absorbent paper, accurate to 0.1g. On the vertical rigid surface, clamp the sample on the sample holder, place the sample in the middle of the spray, 30.5cm away from the nozzle, and spray (27±1)°C water flow directly to the test sample horizontally. The sample was applied for 5 minutes. After spraying, carefully remove the absorbent paper and weigh it quickly, accurate to 0.1g. Calculate the weight increase of the absorbent paper within 5 minutes of spraying time, and take the average value of the test data. If greater than 5.0g, report as +5.0g or >5.0g.

4. Wicking method

The wicking method (also known as capillary effect) is currently the most commonly used and easiest way to directly test the water absorption of fabrics. Usually, the test sample is cut into long strips, one end of the test sample is suspended on the iron stand, and the other end is in contact with the water surface (or immersed in the water to a certain height), after soaking for a certain period of time (f), measure the water climbing through the capillary of the fabric and the fiber pores height (h). The fabric with good water conductivity has strong water absorption, fast water absorption speed (that is, wicking speed), and a large climbing height per unit time, that is, high water conductivity. If during the test, due to the relationship between fabric structure, fiber, yarn and color, the climbing process of water is not obvious, and the naked eye cannot observe it well, you can add a little colorant to the water at this time.

The wicking speed (v) depends on the physical and chemical properties of the fiber and the heat balance process of liquid molecules on the microscopic level; on the macroscopic level, it depends on the shape and direction of the pores. Wicking speed is the height value of water rising in unit time, that is, v(cm/s)=h/t. The strength of water conductivity is related to the size of wicking speed. Therefore, wicking can be used to test the water conductivity of the fabric.