ASTM D7785-21

5.1?The water content of raw or lint cotton determined by this practice, calculated from the required volume of reagent, may be greater, equal to or less than the moisture content measured by standard oven drying methods. These differences may be of significance in commercial transactions (5.2?Standard test methods using volumetric and coulometric Karl Fischer reagent are two of the most widely used procedures for the determination of water.

5.3?The volumetric method is typically used for the routine determination of water in the mass percent range of concentrations. If samples contain very low levels of water, the coulometric technique should be considered (see Test Methods D1533, E1064).

5.4?This practice for testing the water content of cotton can be used for acceptance testing of commercial shipments of lint cotton, manufacturing control and calibration of fast, indirect sensors to measure water.

5.5?Information on the water content of cotton is desirable since the physical properties of cotton are significantly affected by its water content. Variations in the amount of water present, or its regain, affect the mass and hence the market value of a lot of material.

5.6?The observed volume of Karl Fischer reagent used in this practice to analyze a specimen represents the water in the absence of side reactions in an oven supplied with air (3).