1.1 This test method covers a procedure that uses an Optical Fiber Diameter Analyser (OFDA) for the determination of the average fiber diameter and the fiber diameter variation in wool and other animal fibers in their various forms.

This test method may also be applied to other fibers having a round cross section such as some polyamides, polyesters, and glass; it may also be applied to a limited number of polyacrylics and regenerated cellulose-type fibers.

In subsequent sections of this test method, the term "wool" also signifies other animal fibers where applicable.

For fineness specifications of wool, wool top, mohair, mohair top, alpaca, and cashmere, refer to Specifications D 3991, D 3992, D 2252, and Test Method D 2816, respectively.

1.2 The OFDA reports average fiber diameter and standard deviation of fiber diameter in micrometer units (m). The coefficient of variation of fiber diameter is reported as a percentage.

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.