1.1 These test methods cover the determination of the rate at which water vapor passes through films of paint, varnish, lacquer, and other organic coatings. The films may be free films or they may be applied to porous substrates.

1.2 A similar, but more generally applicable test method is Test Methods E96 which should be considered when other materials are involved.

1.3 Two test methods are covered in Test Methods D1653 as follows:

1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. Factors for conversion are stated in 13.2.1.2 and 13.2.2.2.

1.5 There are instruments on the market that purport to measure water vapor transmission of films more easily and rapidly than the methods described in Test Methods D1653 and E96. They run essentially the same kinds of tests as in the ASTM methods, but do so instrumentally. However, it appears that no side-by-side tests have been run comparing results from measurements with such instruments to these ASTM methods for precision and accuracy.

1.6 This standard does not purport to address 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.