1.1 本指南介绍了使用跌落试验来测量电沉积锌、镉、铜和锡涂层的厚度。 注1: 在大多数情况下，这种测量涂层厚度的方法不如合适的涂层厚度计可靠或方便使用（见试验方法 B499 ， B504 和 B568 )。 1.2 本标准并非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。 1.3 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 金属涂层的厚度通常对其性能至关重要。 4.2 当不需要尽可能高的精度时，此程序可用于近似确定。为了进行更可靠的测定，可采用以下方法:试验方法 B487 ， B499 ， B504 和 B568 。 4.3 本试验假设腐蚀性试剂在规定条件下对涂层的溶解速率始终相同。

1.1 This guide covers the use of the dropping test to measure the thickness of electrodeposited zinc, cadmium, copper, and tin coatings. Note 1: Under most circumstances this method of measuring coating thicknesses is not as reliable or as convenient to use as an appropriate coating thickness gauge (see Test Methods B499 , B504 , and B568 ). 1.2 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. 1.3 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 The thickness of a metal coating is often critical to its performance. 4.2 This procedure is useful for an approximate determination when the best possible accuracy is not required. For more reliable determinations, the following methods are available: Test Methods B487 , B499 , B504 , and B568 . 4.3 This test assumes that the rate of dissolution of the coating by the corrosive reagent under the specified conditions is always the same.