5.1 This test method is useful in indicating the differences in weather resistance between various slates. For comparison of relative slate performance, Specification C406/C406M provides a classification that includes expected service life based on depth of softening. This test method provides one element in the comparison of slates.

1.1 These test methods cover two procedures for weather resistance of slate in all outdoor installations by determining the depth of softening after soaking in 1 % sulfuric acid solution by a shear/scratch tester (Test Method A) or by hand scraping (Test Method B).

Note 1: These tests are based on the fact that slates containing calcium carbonate undergo a chemical weathering which produces gypsum and carbon dioxide. The swelling action that results causes disintegration of the slate. Oxidation of iron sulfides (such as pyrite) may also adversely affect weathering durability of a slate. The extent of such action on various slates in the test has been found to correlate with the durability of the materials in actual weathering.

1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.

1.3 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.

1.4 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.