5.1 This test method is considered satisfactory for acceptance testing of commerical shipments since the method has been used extensively in the trade for acceptance testing.

5.1.1 In cases of a dispute arising from differences in reported test results when using this test method for acceptance testing of commercial shipments, the purchaser and the supplier should conduct comparative tests to determine if there is a statistical bias between their laboratories. Competent statistical assistance is recommended for the investigation of bias. As a minimum, the two parties should take a group of test specimens which are as homogeneous as possible and which 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 Student's t-test for unpaired data and an acceptable probability level chosen by the two parties before the testing begins. If a bias is found, either its cause must be found and corrected or the purchaser and the supplier must agree to interpret future test results in the light of the known bias.

5.2 Vinyl-coated glass yarn insect screening and louver cloth are subjected to a heating process to fuse the warp yarns to the filling yarns of the woven structure. The force at which yarns in one direction move over yarns in the opposite direction is a measure of the bond of fusion. The degree of the bond of fusion on the vinyl-coated glass yarn insect screening and louver cloth is used for process control. Fabric stability was formerly called resistance to yarn slippage.