Several standards, including Practices E991, E1164, and Test Methods E1331, E1348 and E1349, require either the presence or absence of fluorescence exhibited by the specimen for correct application. This practice provides spectrophotometric procedures for identifying the presence of fluorescence in materials.

This practice is applicable to all object-color specimens, whether opaque, translucent, or transparent, meeting the requirements for specimens in the appropriate standards listed in 2.1. Translucent specimens should be measured by reflectance, with a standard non-fluorescent backing material, usually but not necessarily black, placed behind the specimen during measurement.

This practice requires the use of a spectrophotometer in which the spectral distribution of the illumination on the specimen can be altered by the user in one of several ways. The modification of the illumination can either be by the insertion of optical filters between the illuminating source and the specimen, without interfering with the detection of the radiation from the specimen, or by interchange of the illuminating and detecting systems of the instrument or by scanning of both the illuminating energy and detection output as in the two-monochromator method.

The confirmation of the presence of fluorescence is made by the comparison of spectral curves, color difference, or single parameter difference such as ΔY between the measurements.

Note 2-In editions of E1247 - 92 and earlier, the test of fluorescence was the two sets of spectral transmittances or radiance factor (reflectance factors) differ by 1 % of full scale at the wavelength of greatest difference.

Either bidirectional or hemispherical instrument geometry may be used in this practice. The instrument must be capable of providing either broadband (white light) irradiation on the specimen or monochromatic irradiation and monochromatic detection.

This practice describes methods to detect the presence of fluorescence only. It does not address the issue of whether the fluorescence makes a significant or insignificant contribution to the colorimetric properties of the specimen for any given application. The user must determine the practical significance of the effect of fluorescence on the color measurement.