【国外标准】 Standard Practice for Testing Water Resistance of Coatings Using Controlled Condensation

4.1 Water can cause degradation of coatings, so knowledge of how a coating resists water is helpful in predicting its service life. Failure in a condensation test may be caused by a number of factors including a deficiency in the coating itself, contamination of the substrate, or inadequate surface preparation. The test is therefore useful for evaluating coatings alone or complete coating systems.4.2 Condensation tests of coatings are used for specification acceptance, quality control, and research and development of coatings and substrate treatments. These tests usually result in a pass or fail determination but the degree of failure also may be measured. A coating system is considered to pass if there is no evidence of water-related failure after a specified period of time.4.3 Results obtained from the use of condensation tests in accordance with this practice should not be represented as being equivalent to a period of exposure to water in the natural environment, until the degree of quantitative correlation has been established for the coating or coating system.4.4 The test is usually conducted on metal, plastics, or wood specimens with the coating facing the inside of the chamber. However, it is possible to test the blister resistance of house coatings on wood specimens by mounting the uncoated wood surface facing the inside of the chamber.4.5 This practice can be used for corrosion tests particularly if the specimens are periodically dried. While corrosion products will drain into the water bath, they are not carried into the vapor that condenses on the test specimens.1.1 This practice covers basic principles and operating procedures for testing water resistance of coatings using controlled condensation. Condensation is produced by exposing one surface of a coated specimen to a heated, saturated mixture of air and water vapor, while the reverse side of the specimen is exposed to the cooling effect of room temperature air. This practice is derived from research of the Cleveland Society for Coatings Technology.21.2 This practice is limited to the methods of obtaining, measuring, and controlling conditions and procedures of controlled condensation tests. It does not specify specimen preparation, specific test conditions, or evaluation of results.NOTE 1: Alternative practices for testing water resistance of coatings include Practices D870, D1735, and D2247.1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.1.4 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.1.5 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.