5.1 The most direct and accessible methods for obtaining the color coordinates of object colors are by instrumental measurement using spectrophotometers or spectrocolorimeters with either hemispherical or bidirectional optical measuring systems. This test method provides procedures for such measurement by spectrophotometry using a bidirectional (0:45 or 45:0) optical measuring system. The method for color and color difference measurement using filter colorimeters is contained in Test Method E1347.

5.2 This test method is especially suitable for measurement of the following types of specimens for the indicated uses (see also Guide E179 and Practice E805):

5.2.1 Object-color specimens of any gloss level for color assessment.

5.2.2 Object-color specimens with physically flat, smooth surfaces from which to obtain data for use in computer colorant formulation.

5.2.3 Retroreflective specimens.

Note 1-To ensure inter-instrument agreement in the measurement of specimens with intermediate gloss, for formulation, or of retroreflective specimens, significantly tighter tolerances than those given in Practice E1164, Influx and Efflux Conditions, 45°:Normal (45:0) and Normal:45° (0:45) Reflectance Factor section, may be required for the instrument angles of illumination and viewing. Information on the required tolerances is being developed.

5.3 This test method is not recommended for measurement of specimens with bare metal surfaces for color assessment, for which the use of hemispherical measurement geometry, as with an integrating-sphere type instrument, is preferable (see Guide E179).