ASTM D 1577 : 2007

1.1 These test methods cover the measurement of mass per unit length (linear density) of textile fibers and filaments. Direct weighing and vibroscope procedures with modifications for crimped and uncrimped fibers are included. The options and sections are listed below.

Note 1 - For linear density of short lengths of yarn, refer to Test Method D 1059. For cotton linear density, refer to Test Methods D 1769, and D 2480. For measurement of wool diameter, refer to Test Methods D 1282, D 2130 and D 3510.

1.2 The crimp, taper and cross-sectional shape of the fiber may influence the linear density measured by single-fiber weighing and vibroscope.

1.3 These test methods measure the linear density of fibers with moisture in equilibrium with the standard atmosphere for testing textiles. The fiber moisture under these conditions is not necessarily the same as the commercial moisture regain for the fibers.

1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.

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 test method option covers the measurement of the average linear density of textile fibers by cutting and weighing.

1.6 This test method option covers the measurement of the linear density of single fibers. This option is not recommended for fibers shorter than 30 mm.

1.7 These test methods options cover procedures for measuring the linear density of single fibers using the vibroscope. These options are particularly applicable to staple fibers with linear density below 10 dtex (9 denier). Option C-1 is for uncrimped fibers and Option C-2 is for crimped fibers.

1.8 The following procedures are suitable for use on uncrimped fibers or on fibers from which the crimp is removed by the tension applied in the test. Choice of the appropriate procedure is determined by the arrangement of the components comprising the vibroscope apparatus.

1.9 Since the presence of crimp leads to falsely high linear density values, it must be removed by the use of sufficiently heavy tensioning weights. This requirement limits the type of vibroscope which may be used to a variable frequency unit with adequate range to allow for the measurement of the fundamental frequency of vibration of short lengths of fiber under the tension required. Note 2 - When tension normally applied by the equipment used in the procedure described in is adequate to remove crimp, this procedure may be used with lightly crimped fibers.