ASTM D4061-13 PDF

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).

Note 1-Includes observation angle α, entrance angle β, viewing angle ν_a, co-viewing angle ν_c, and co-entrance angle β_c. The retroreflector axis, illumination axis, and observation axis all lie in the same plane.

FIG. 1 Diagram Illustrating Geometry for Measurement of Horizontal Coatings Specimens

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.

FIG. 2 Illustration of Typical Rate of Change of Retroreflectance Versus Observation Angle for Horizontal Retroreflective Material Measured at 86° Entrance Angle

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 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

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 and health practices and determine the applicability of regulatory limitations prior to use.