ASTM D861-01a PDF

1.1 This practice covers the use of the tex system to designate the linear density (number, or count) of fibers and of yarns made from any type of fiber or combination of fibers. It is also applicable to other textile materials, including yarn intermediates (slivers, rovings, tops, etc.), single or plied yarns, cords, and threads.

Note 1 - The mass per unit length concept of linear density is applicable to any material which has a high ratio of length to cross section.

1.2 Conversion factors for various indirect and direct yarn numbers to exact tex equivalents can be found in Standard Tables D 2260.

1.3 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.