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1.1 These test methods cover measurement of moisture in textile materials as (1) moisture content or pick-up using ambient air for oven-drying, (2) moisture content or pick-up using standard atmosphere for testing textiles for oven-drying, (3) moisture content or pick-up at moisture equilibrium, and (4) moisture regain. These test methods are applicable to all fibers natural or man-made, and in all forms from fiber or filament to finished fabric, subject to the limitations set forth in 1.1.1 through 1.1.4. Blends of fibers shall also be tested by these methods.

1.2 In Procedures 1, 2, and 3, alternative techniques are described for weighing oven-dried specimens: in the oven while hot, and outside the oven at room temperature.

1.3 The word water refers to the chemical compound H₂0. The terms water and moisture are frequently used interchangeably in the literature and in the trade even when the “moisture” is known to contain other volatile materials. When the loss during oven exposure is not known to be all water, it shall be considered a “volatiles loss” rather than a “moisture loss” for technical accuracy.

1.4 Moisture calculations commonly involve the mass of a specimen that has been dried by heating in an oven. If the air in the oven contains moisture, the oven-dried specimen will contain moisture (in equilibrium with that in the oven air) even when it no longer shows a significant change in mass. Therefore, if a very precise measurement of the moisture present is required and oven drying is used, the mass must be exposed to desiccated air until it shows no further significant change in mass.

1.5 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.

1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

5.1 Test Methods D2654, Procedure 1, is used in the trade as a basis for rejecting abnormally wet material, but it is not recommended for routine acceptance testing of commercial shipment. Procedure 2 is used by the trade and is recommended for acceptance testing of commercial shipments except as stated in Note 1 . Procedure 3 is used to determine the moisture in a material in a given moisture-equilibrium situation and is not used for acceptance testing of commercial shipments. Procedure 4 is for research and development and is recommended for determining the standard moisture regain of a material although there will usually be a bias between buyer and producer data because the produce is usually able to obtain material without surface material, mostly finishes.

5.2 The measurement of moisture is important for several reasons, including the following:

5.3 Between Procedures 1 and 2, the choice for use is dependent primarily on the degree of accuracy required in the result. They are oven-drying procedures and have the virtue of simplicity and economy, with Procedure 1 having the added feature of not requiring a special drying atmosphere for the oven. Both are subject to certain limitations, however, that are avoided by toluene distillation (Note 2).

5.4 It is sometimes possible, and preferable, when sampling a material for the determination of moisture to select sampling units of a size which coincide with the size required by the method for a test specimen. In these instances, the mass shall be determined immediately, and if the mass of the oven-dry material is to be determined, no intermediate steps are necessary. However, in other instances, it will be necessary to perform some intermediate manipulation with the material, such as compositing or subsampling. For such instances to circumvent the problem of moisture loss or gain after sampling, provisions are made in these methods to stabilize the material in the working laboratory atmosphere, and equations are provided with correction terms to relate the measured moisture to the amount which existed at the time when the sample was taken.

5.5 While moisture regain is not a frequently tested property, it has an importance, once established. Commercial moisture regains (see Table 1 in D1909) are values adopted for use in determining commercial mass and fiber blends which meet government regulations. These values are usually slightly higher than experimental standard moisture regain values or an average for a class which has a range.

5.6 The measurement of moisture regain of a fiber is affected by any surface material present, the procedure (technique, solvent) used to remove the material, the dryness achieved and the atmosphere (temperature, humidity) in which the dry material is conditioned.