1.1 This test method describes the instrumental measurement of the retroreflective properties of horizontal surfacing materials, such as traffic stripe paint systems, traffic tapes, and traffic surface symbols.

1.2 Specimen preparation, size, and shape must be determined and specified by the user of this test method. Likewise, the user must specify the observation and entrance angles to be used (see Fig. 1).

1.3 The geometric requirements of this test method are based on materials for which the relative retroreflectance changes less than approximately 50% over the observation angle range from 0.2 to 0.5°. This is illustrated in Fig. 2.

1.4 This test method is a laboratory test and requires a facility that can be darkened sufficiently so that stray light does not affect the test results. This facility must be capable of housing the required 15-m test distance.

1.5 This standard does not purport to address all of the safety problems, 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.