5.1 Test Method D1574 is considered satisfactory for acceptance testing since the method has been used extensively in the trade for acceptance testing.

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.

5.3 The residues obtained in this test may be subjected to chemical analysis for identification and assay of the component materials, if desired.

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.