ASTM D1448-11

This test method is considered satisfactory for acceptance testing when the levels of the laboratories are controlled by the use of the same reference standard cotton samples because the current estimates of between-laboratory precision are acceptable under these conditions. If there are differences of practical significance between reported test results for two laboratories (or more), comparative tests should be performed to determine if there is a statistical bias between them, using competent statistical assistance. As a minimum, ensure the test samples to be used are as homogeneous as possible, are drawn from the material from which the disparate test results were obtained, and are randomly assigned in equal numbers to each laboratory for testing. The test from the two laboratories should be compared using a statistical test for unpaired data, at a probability level chosen prior to the testing series. If a bias is found, either its cause must be found and corrected, or future test results for that material must be adjusted in consideration of the known bias.

The micronaire reading of cotton fibers is a function of both fineness and maturity and is related to mill processing performance and to the quality of the end products. Factors correlated with micronaire reading include cleaning efficiency, neppiness, and the strength and uniformity of the yarn.

Note 2—A modification of this test method is used in commercial trading to select bales which will conform to contract guarantees for specified micronaire readings (refer to D5867). For this purpose, it is usual practice to test only one specimen per sample.

1.1 This test method covers the determination of the micronaire reading of loose cotton fibers by measuring the resistance of a specific mass (plug) of cotton fibers to air flow under prescribed conditions.

Note 1—For other methods for determining the fineness of fibers based on the air-flow principle, refer to Test Method D1449, Test Method for Specific Area and Immaturity Ratio of Cotton Fibers (Arealometer Method), and to Test Method D1282, Test Method for Resistance to Air Flow as an Indication of Average Fiber Diameter of Wool Top, Card Sliver, and Scoured Wool.

1.2 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.