Active Standard ASTM D4061 | Developed by Subcommittee: E12.10
Book of Standards Volume: 06.01
Historical (view previous versions of standard)
Significance and Use
5.1 The quantity coefficient of retroreflected luminance is a measure of the reflected luminance in the direction of the observer. This is the light returned by the retroreflective surface to the observer from the source, which in practice is the vehicle headlamp.
5.3 Since this test method is a laboratory procedure, test specimens must be prepared so that they can be mounted on the specimen holder. Specimens measured by this laboratory method may be used as transfer standards for the calibration of portable instrumentation.
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.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
CIE PublicationNo. 54 Retroreflection Definition and Measurement
E284 Terminology of Appearance
E308 Practice for Computing the Colors of Objects by Using the CIE System
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E808 Practice for Describing Retroreflection
E809 Practice for Measuring Photometric Characteristics of Retroreflectors
ICS Number Code 87.040 (Paints and varnishes)