1.1 This test method describes the techniques for comparing the brightness of the penetrants used in the fluorescent dye penetrant process. This comparison is performed under controlled conditions that eliminate most of the variables present in actual penetrant examination. Thus, the brightness factor is isolated and is measured independently of the other factors which affect the performance of a penetrant system. 1.2 The brightness of a penetrant indication is affected by the developer with which it is used. This test method, however, measures the brightness of a penetrant on a convenient filter paper substrate which serves as a substitute for the developer. 1.3 The brightness measurement obtained is color-corrected to approximate the color response of the average human eye. Since most examinations are done by human eyes, this number has more practical value than a measurement in units of energy emitted. Also, the comparisons are expressed as a percentage of some chosen standard penetrant because no absolute system of measurement exists at this time. 1.4 The measurements made by this standard compare the brightness of a candidate penetrant to that of a standard penetrant when tested according to the technique. There is no known correlation between the results obtained and the brightness of actual flaw indications obtained using the penetrant in inspection. 1.5 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. 1.6 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.