Significance and Use
5.1.1 In case of a dispute arising from differences in reported test results when using Test Method D1574 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 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 Student's t-test 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 in the light of the known bias.
5.2 This test method may be used to estimate the quantity of oil, grease, and waxy materials remaining on or in wool fibers after scouring, or the quantity of lubricant added before carding or remaining after carding, or the quantity of such materials added or removed in subsequent processing operations.
5.4 The specified solvent in this test method does not remove some materials, such as soaps, that may be present in wool and hence in some cases may reflect more closely the added content of some extractables in wool such as oils. When such materials are present and an estimate of their quantity is desired, some other solvent or combination of solvents should be used as specified in a material specification or by agreement. The information in the Annex of this test method may be useful for this purpose. Various solvents have been used in the past, and are still used to some extent. Many of these solvents are undesirable, however, because of flammability, toxic or anesthetic effects, or unpleasant odors. Trichlorotrifluoroethane is nonflammable, has a very low level of toxicity, and a high degree of stability and is a good solvent for most fatty or mineral oils, greases, and waxes. The specified solvent, under conditions of the test, was found in interlaboratory test not to extract wool protein.
1.1 This test method covers the determination of the amount of extractable matter in samples of all forms of wool, except grease wool, that is extractable with a non-flammable vapor degreasing and cleaning solvent.