1.1 This test method covers the estimation of the average fiber diameter of wool fibers by use of the Port-Ar, and the WIRA Fiber Fineness Meter instrument, which operate on the air-flow principle. Other air-flow instruments have not been tested with this method. The method is directly applicable to non-medullated, carded wool and wool top.

1.2 This test method is applicable to grease wool and scoured wool after the samples of such materials have been prepared as directed in Test Method D 2130.

Note 1-The use of the Micronaire instrument for measuring the fineness of cotton fibers is covered in Test Method D 1448. The assignment of grade for wool and mohair is covered in Specifications D 3991 and D 3992.