AATCC 35:2018 pdf download.Water Resistance: Rain Test
6. Test Specimens
6.1 A minimum of three specimens of 20 x 20 cm is cut from the test fabric. The fabric samples and the blotting paper should be conditioned in an atmosphere of65土5% RH and21士2°C (70士4°F) for at least 4 h before testing.
7. Procedure
7.1 The test specimen (see 11.5), backed by a 15.2 x 15.2 cm standard pa- per blotter weighed to the nearest0.1 g is clamped in the specimen holder and the assembly is mounted in a vertical rigid support frame. The specimen assembly is positioned into the central portion of the spray at a distance of 30.5 cm from the face of the spray nozzle (see 11.6). A hor- izontal water spray at 27土1°C (81士 2°F) (see 11.2) is directed against the specimen and is allowed to continue for a period of 5 min. At the end of the spray period the blotter is carefully removed and quickly reweighed to the nearest0.1 g
8. Evaluation
8.1 Water penetration as indicated by the increase in mass of the blotting paper during the 5 min test period is calculated, and the average for the three test speci- mens is reported. Individual dctermina- tions or average values of over 5.0 g may be simply reportedto5+gor> 5g. 8.2 In order to obtain a complete over- all picture of the penetration resistance of a fabric or fabric combination the average penetration with different pressure heads on the nozzle should be obtained. The pressure head should be varied by 300 mm increments in order to determine (a) the maximum head at which no penetra- tion occurs, (b) the change in penetration with increasing head and (C) the mini- mum head required to cause “break- down”or the penetration of more than5 g of water. At each pressure head a mini- mum of three specimens should be tested in order to obtain the average penetration for that head.AATCC 35 pdf download.