ASTM D1653-13 (R2021) pdf free download.Standard Test Methods for Water Vapor Transmission of Organic Coating Films.
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, hut more generally applicable test method is Test Methods E96 which should he considered when other materials are involved.
1.3 Two test methods are covered in Test Methods Dl 653 as follows:
1.3.1 Test Method A—Dry Cup Method, and
1.3.2 Test Method B—Wet (Payne) Cup Method.
1 .3.3 Agreement should not be expected between results obtained by different methods or test conditions. The method that most closely approaches the conditions of use should be selected.
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, hut 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.
3. Terminology
3. 1 Definitions of Terms Specific to This Standard:
3. 1 . 1 water vapor transmission rate, WVT mi—the steady water vapor flow in unit time through unit area of a body, between two specific parallel surfaces, under specific conditions of temperature and humidity at each surface. Accepted inch-pound unit is grains per square foot per hour. Accepted SI unit is grams per square metre per 24 h.
3.1.2 water vapor permeance, WVP, n—the steady water vapor flow in unit time through unit area of a body (WVT) induced by unit vapor pressure difference (Ap) between the two surfaces of a coating. Therefore, WVP = WVT/Ap. Accepted inch-pound unit is grains per square foot per hour per inch of mercury (called a perm). Accepted SI unit is grams per square metre per 24h per millimetre of mercury (called a metric perm).ASTM D1653 pdf download.