ASTM D1577 – Standard Test Methods for Linear Density of Textile Fibers
Description:
Significance and Use
4.1 Option A for bundle weighing of Test Method D1577 is used in the trade for acceptance testing of commercial shipments. Option B for single-fiber weighing and Option C for the vibroscope may be used for acceptance testing (see Section 37); however, caution is advised when using Option B or Option C because between-laboratory precision information is incomplete. Comparative tests as directed in 4.1.1 may be advisable.
4.1.1 In case of dispute arising from differences in reported test results when using Test Method D1577 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 samples that are as homogeneous as possible and that are from a lot of material of the type in question. These samples should then be randomly assigned in equal numbers to each laboratory for testing. The average results from the two laboratories should be compared using the appropriate statistical analysis and a probability level chosen by the two parties before testing is begun. If a bias is found, either the cause must be found and corrected or the purchaser and the supplier must agree to interpret future test results for that material with consideration to the known bias.
4.2 Option A for bundle weighing is generally considered to be the referee procedure for acceptance testing.
4.3 Option A is not recommended for measurement of linear density of blends of production fibers having different nominal linear densities.
4.4 The accuracy of the linear density values obtained by Options A and B is dependent upon the accuracy with which the fibers can be cut and weighed.
NOTE 2: On short staple fiber, an accuracy in cutting of 1.0 % is difficult to obtain. This problem is further complicated if crimp is present in the fibers.
4.4.1 The accuracy of weighing can be controlled by the number of fibers composing the bundle. However, with short fiber of low linear density the number of fibers to be counted becomes prohibitive unless the bundle mass is kept low.
4.5 Options A and B are fundamental procedures which are used to standardize the vibroscope equipment used in Options C1 and C2.
4.6 Test Method Options B and C are most useful for the measurement of linear density of single fibers when further tests upon the same test specimen are required, for example, tension tests and adjustment of the data obtained for the linear density of the test specimen. These options offer advantages in accuracy and ease of operations over calculation from specific gravity and microscopically measured cross-sectional area.
4.7 Additional information specific to Option C is in Section 26.
Scope
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.
| Option | Sections | |
| A—Fiber Bundle Weighing | 7 – 15 | |
| B—Single-Fiber Weighing | 16 – 23 | |
| C—Vibroscope, General | 24 – 30 | |
| 35 and 36 | ||
| C1—Uncrimped Fibers | 31 and 32 | |
| C2—Crimped Fibers | 33 and 34 | |
| Precision and Bias | 37 and 38 | |
NOTE 1: For linear density of short lengths of yarn, refer to Test Method D1059. For cotton linear density, refer to Test Methods D1769 and D2480. For measurement of wool diameter, refer to Test Methods D1282, D2130, and D3510.
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.
ASTM D156