4.1 Moisture content is one of the most important variables affecting the properties of wood and wood-based materials. The procedures in these test methods are structured to permit the full range of use from fundamental research to industrial processing. Method A is designed for obtaining the most precise values of moisture content consistent with the needs of the user. It also provides means of assessing variability contributed by the oven or specimen hygroscopicity, or both. In addition, criteria are described for defining the endpoint in oven-drying. Method A is the reference (primary) standard for determining moisture content of wood and wood-based materials. Methods B through D are secondary methods to permit relatively simple procedures of measuring moisture content, but with less precision than Method A. However, greater precision may be obtained with supporting data by using the appropriate procedures in Method A.

1.1 These test methods cover the determination of the moisture content (MC) of wood, veneer, and other wood-based materials, including those that contain adhesives and chemical additives. The test methods below describe primary (A) and secondary (B through D) procedures to measure moisture content:

Method A—Primary Oven-Drying Method

Method B—Secondary Oven-Drying Method

Method C—Distillation (Secondary) Method

Method D—Other Secondary Methods.

1.2 The primary oven-drying method (Method A) is intended as the sole primary method. It is structured for research purposes where the highest accuracy or degree of precision is needed.

1.3 The secondary methods (B through D) are intended for special purposes or under circumstances where the primary procedure is not desired or justified. In these procedures, moisture content values cannot be reported with an accuracy greater than integer percentage values. However, a greater level of accuracy may be reported if the appropriate primary procedures are used.

1.4 Distillation (secondary) method is intended for use with materials that have been chemically treated or impregnated such that the oven-drying procedures introduce greater error than desired in the results.

1.5 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.