1.1 本规程涵盖了测试涂层耐水性的基本原理和操作程序，方法是将涂层试样暴露在保持100%相对湿度的大气中，以便在试样的所有表面上形成冷凝水。 1.2 该实践使用在暴露区域内产生轻微温差的技术，以在涂层试样上形成冷凝。当较暖的饱和空气经过较冷的试样时，水以冷凝的形式沉积在试样上。 1.3 这种做法将整个试样放置在暴露区域，使所有表面都能形成冷凝水。这使得这种做法适用于平板以及大型或三维对象。这种做法与其他方法不同，在其他方法中，冷凝仅在前涂层表面上形成，而后表面在暴露区域之外。其他测试也可能在表面沉积水滴，但其来源不是冷凝（例如喷水）。 注1: 测试涂层耐水性的替代实践包括实践 D870 , D1735 和 D4585 . 1.4 本规程仅限于在100%相对湿度下进行试验的条件和程序的获取、测量和控制方法。它没有具体说明样本制备或结果评估。 1.5 以国际单位制表示的数值应视为标准。括号中给出的值仅供参考。 1.6 本标准并不旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 ====意义和用途====== 4.1 水会导致涂层退化，因此了解涂层如何防水有助于评估其在实际使用中的表现。在100%相对湿度下测试失败可能是由许多因素引起的，包括涂层本身的缺陷、基材的污染或表面处理不足。因此，该实践对于评估单独的涂层或完整的涂层系统是有用的。 4.2 100%相对湿度下的测试用于规范验收、质量控制以及涂层和基材处理的研发。某些测试用于在任意时间确定是否通过。如果一段时间后没有与水有关的故障迹象，则认为涂层系统合格。其他测试用于监测作为暴露时间函数的失效程度。 4.2.1 在其他特定材料的测试方法中，通常会设置任意的合格/不合格水平和所需的测试持续时间。 该实践的用户可以单独使用已知的控制性能来设置测试终点。另一种选择是继续测试，直到所有样本都失败，并利用达到失败的时间来区分性能。 4.3 根据本规程使用100%湿度测试获得的结果不应表示为相当于在自然环境中暴露于水的一段时间，直到涂层或涂层系统的定量相关性已经确定。 4.4 试验室可以是一个小的实验室机柜，也可以是一间足够大的房间，可以放一辆汽车或卡车。一些汽车制造商在保持100%相对湿度的房间里测试整车。可以进行腐蚀试验，因为从供试品中滴下的冷凝物没有再循环。

1.1 This practice covers the basic principles and operating procedures for testing water resistance of coatings by exposing coated specimens in an atmosphere maintained at 100 % relative humidity so that condensation forms on all surfaces of test specimens. 1.2 This practice uses the technique of creating a slight temperature differential within the exposure area to form condensation on the coated specimens. As the warmer saturated air passes the cooler specimens, water is deposited onto the specimens in the form of condensation. 1.3 This practice places the entire specimen in the exposure area allowing condensation to form on all surfaces. This makes this practice suitable for flat panels as well as large or 3D objects. This practice differs from other methods where condensation is only formed on the front coating surface, while the back surface is outside the exposure area. Other tests may also deposit water droplets on the surface but where the source is not from condensation (for example, water spray). Note 1: Alternative practices for testing the water resistance of coatings include Practices D870 , D1735 , and D4585 . 1.4 This practice is limited to the methods of obtaining, measuring, and controlling the conditions and procedures of tests conducted in 100 % relative humidity. It does not specify specimen preparation, or evaluation of results. 1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.6 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. 1.7 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. ====== Significance And Use ====== 4.1 Water can cause the degradation of coatings, so knowledge of how a coating resists water is helpful for assessing how it will perform in actual service. Failure in tests at 100 % relative humidity may be caused by a number of factors including a deficiency in the coating itself, contamination of the substrate, or inadequate surface preparation. This practice is therefore useful for evaluating coatings alone or complete coating systems. 4.2 Tests at 100 % relative humidity are used for specification acceptance, quality control, and research and development for coatings and substrate treatments. Some tests are used for a pass or fail determination at an arbitrary time. A coating system is considered to pass if there is no evidence of water-related failure after a period of time. Other tests are used to monitor degree of failure as a function of exposure time. 4.2.1 Arbitrary pass/fail levels and the test durations required are typically set in other material specific test methods. Users of this practice alone may use the known performance of the controls to set test end points. Another option is to continue the test until all specimens have failed, and use the time to reach failure as a way to differentiate performance. 4.3 Results obtained from the use of 100 % humidity 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 chamber can be a small laboratory cabinet or a room large enough to hold an automobile or a truck. Some automobile manufacturers test completed vehicles in rooms maintained at 100 % relative humidity. Corrosion tests can be conducted, as the condensate dripping off the test articles in not recirculated.