ASTM-D870 › Standard Practice for Testing Water Resistance of Coatings Using Water Immersion
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1.1 This practice covers the basic principles and operating procedures for testing water resistance of coatings by the partial or complete immersion of coated specimens in distilled or de-mineralized water at ambient or elevated temperatures. Although the apparatus and procedure could be employed in immersion tests using solutions of various materials in water, this practice is limited to tests in water alone.
1.2 This practice is limited to the methods of obtaining, measuring, and controlling the conditions and procedures of water immersion tests. It does not specify specimen preparation, specific test conditions, or evaluation of results.
Note 1: Alternative practices for testing the water resistance of coatings include Practices , , and .
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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 and health practices and determine the applicability of regulatory limitations prior to use.
Significance and Use
4.1 Immersion in water can cause the degradation of coatings. Knowledge on how a coating resists water immersion is helpful in predicting its service life. Failure in a water immersion 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 Water immersion tests are used for research and development of coatings and substrate treatments, specification acceptance, and quality control in manufacturing. These tests typically result in a pass or fail determination, but the degree of failure may also 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 water immersion 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 Corrosion tests of a scribed coating on a ferrous substrate are impractical in water immersion tests as the corrosion products tend to contaminate the water bath. Continuous overflow of the test tank is sometimes required to maintain consistent water quality.
4.5 The apparatus for the test is relatively inexpensive and can be as simple as a glass beaker with a stirrer. It is also possible to use very large tanks for testing coated pipe or other large coated products.
adhesion; blistering; immersion; resistance-water; rust;; ICS Number Code 25.220.20 (Surface treatment)
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March 15, 2015