ASTM D4912-07

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.

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.

1.1 This test method provides a procedure for evaluating fabric stability by measuring the resistance to yarn slippage of filling yarns over warp yarns, or warp yarns over filling yarns in vinyl-coated glass yarn insect screening and louver cloth.

1.2 This test method shows the values in both SI units and inch-pound units. “SI units” is the technically correct name for a system of metric units known as the International System of Units. “Inch-pound units” is the technically correct name for the customary units used in the United States. The values expressed in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with this standard.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.