The procedures in this standard can be used for acceptance testing of commercial shipments of coated and laminated fabrics for architectural use since these test methods have been used extensively in the trade for acceptance testing. Caution is advised, however, when testing adhesion of coating to fabric and breaking strength after crease fold because between laboratory precision is known to be poor (see 24.2). For these cases, comparative tests conducted, as directed in 5.1.1, may be advisable.

5.1.1 In cases of a dispute arising from differences in reported test results when using Test Methods D 4851 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 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 appropriate statistical analysis for unpaired data and an acceptable probability level chosen by the two parties before the testing is begun. 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 with consideration of the known bias.

The uses and significance of specific properties are discussed in the appropriate sections of specific test methods.