The spray rating is determined by comparing the appearance of the tested specimen with descriptive standards and photographs. The AATCC Spray Test Rating Chart is available for this purpose.The Spray Test is a simple method to determine the resistance of any fabric, which may or may not have been given a water-resistant or water-repellent finish, to surface wetting by water. It is not intended to predict waterproofness, since it does not measure the penetration of water through fabric.
Working Procedure:
The sample fabric is mounted on the embroidery hoop and fixed on the instrument at 45o.
Now the beaker is filled with 250 cc water and poured on the funnel.
The water is showered through spray nozzle on the fabric.
After spraying has finished the sample holder is removed and the surplus water removed by tapping the frame 6 times against a solid object, with the face of the sample facing the solid object.
The water repellency is assessed from the spray rating chart.
5 tests should be made and the nearest rating assigned to each, since no interpolation is allowed, i.e. a rating for a specimen cannot be 75.
The mean of the 5 ratings is taken as the result.
Result:
Water repellency of a 100% cotton fabric is 0.
Water repellency of a polyester fabric is 0.
Water repellency of a umbrella fabric is 70.
Water repellency of a parachute fabric is 100.
Remark:
According to the type of fabric water repellency varies from 0-100. From the experiment we can understand this. It is mainly selected depending on the end use of fabrics.
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