Standard Test Method for Moisture in Cotton by Oven-Drying

Abstract

5.1 This test method for testing the moisture content of cotton can be used for acceptance testing of commercial shipments of lint cotton provided the between-laboratory bias is known. 5.1.1 If there are differences or practical significance between reported test results for two laboratories, or more, comparative test should be performed to determine if there is a statistical bias, using competent statistical assistance. As a minimum, use test samples as homogeneous as possible, drawn from the material from which the disparate test results are obtained, and assigned randomly in equal numbers to each laboratory for testing. Other materials with established test values may be used for this purpose. Compare the test results from the two laboratories 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 must be adjusted in consideration of the known bias. 5.2 Information on the moisture content of cotton is desirable since the physical properties of cotton are significantly affected by its moisture content. High moisture content increases flexibility, toughness, elongation, and tensile strength. Too high a moisture content causes difficulty in processing due to the tendency of the stock to “lap-up” on drafting rolls. Low moisture, on the other hand, facilitates cleaning but increases the brittleness of the fiber and results in fiber breakage during ginning, cleaning, and mill processing. Low moisture also increases fly waste and may cause manufacturing difficulties due to static electricity. 5.3 Variations in the amount of moisture present affect the mass and hence the market value of a lot of material sold at a definite price per unit mass. Knowledge of the moisture content or regain can be accordingly an important financial consideration. 5.4 Moisture content variation affects lap, sliver, and roving linear density which in turn controls yarn number variation. 5.5 The mass of the oven-dry specimen used in this method is the mass observed after the specimen has been dried in an oven supplied with ambient air. The observed mass is accordingly subject to minor variations. These variations, however, are believed to be without significance in commercial transactions.