5.1 This is a quick method used for the determination of the approximate yarn number of short-length specimens taken from packages or fabrics.

5.2 Because any error present in the reported length of the specimen is multiplied many times when calculating the theoretical yarn number using Eq 2 or Eq 3, it is extremely important that the length be measured as precisely as practicable.

5.3 For the analysis of fabrics, this test method is adequate for estimating the approximate yarn number of the yarn used to weave or knit the fabric, but the results obtained by this test method may not agree with the nominal yarn number of the yarns actually used to make the fabric because of the changes in the yarn number produced by the weaving or knitting operations, the finishing treatments, and the dissecting operations. This test method is suitable for the evaluation of yarns as they occur in the finished fabric, when that information is needed.

5.4 The yarn number obtained from the lengths taken from packages should not be expected to agree exactly with the values obtained by the use of the more precise methods of determining the yarn number included in Test Method D1907. If a sufficient number of consecutive specimens were tested, however, a close agreement with Option 1 of Test Method D1907 can be expected.

5.5 This test method is designed to measure the yarn number of the single yarns present as a component of a plied yarn and the yarn number of the original single yarns used to produce a high twist yarn for a crepe fabric.

5.6 This test method is not recommended for acceptance testing because of the short lengths used. In some cases, the purchaser and the supplier may have to test a commercial shipment of one or more specific materials by the best available method, even though the method has not been recommended for acceptance testing of commercial shipments.

5.6.1 In such a case, if there is disagreement arising from the differences in values reported by the purchaser and supplier when using this method for acceptance testing, the statistical bias, if any, between the laboratory of the purchaser and the laboratory of the supplier should be determined with each comparison being based on testing specimens randomly drawn from one sample of material of the type being evaluated.

1.1 This test method covers the determination of the yarn number of all types of cotton, woolen, worsted, and man-made fiber yarns taken from packages; or from any textile fabrics in which the yarns are intact and can be removed in measurable lengths. The test method is not applicable to yarns taken from napped or cut pile fabrics. Because this test method is based on short-length specimens, the results should only be considered as approximations of yarn number.

Note 1: For a more precise procedure for the determination of yarn number, refer to Test Method D1907.

Note 2: The following additional methods for the determination of yarn number have been approved for yarns made from specific fibers: Specification D541, D578, and D681.

1.2 This test method is applicable to yarns which stretch less than 5 % when tension on yarn is increased from 0.25 to 0.75 cN/tex (0.25 to 0.75 gf/tex). By mutual agreement it may be adapted to yarns which stretch more than 5 % by use of tension lower than that specified in the method for elastomers or use of tension higher than that specified in the method to pull the crimp out of textured yarns.

1.3 The values stated in SI units are to be regarded as standard; the values in inch-pound units are reported as information only.

1.4 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.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.