5.1 This test method for testing for water retention of fibers after centrifuging is not recommended for acceptance testing of commercial shipments because the test is more appropriate for development and research. However, if the test is to be used for acceptance testing, comparative tests as described in 5.1.1 are advised.

5.1.1 In the case of a dispute arising from differences in reported test results using Test Method D2402 for acceptance testing of commercial shipments, the purchaser and the supplier should conduct comparative tests to determine if statistical biases exist between their laboratories. As a minimum, the two parties should take a group of test specimens that are as homogeneous as possible and that are from a lot of material of the type in question. The test specimens should then be randomly assigned in equal numbers to each laboratory for testing. The average results from the two laboratories should be compared using the Student's t-test for unpaired data with an acceptable probability level chosen by the two parties while designing the test program. If the analysis shows a bias, its cause must be found and corrected, or the purchaser and supplier must agree to interpret future test data with consideration for the known bias.

5.2 The amount of water retained by a fiber mass increases with an increase in the hydrophilic tendency of the fiber. Thus the data obtained can be used to indicate the following:

5.2.1 Differences in water retention between the various man-made and natural fibers,

5.2.2 Degree of cross-linking in cellulosic fibers,

5.2.3 Damage incurred by wool and silk fibers due to alkaline processing, and

5.2.4 Persistence of water-repellent treatments.