1.1 This test method covers the instrumental measurement of specimens resulting in color coordinates and color difference values by using a tristimulus colorimeter, also known as a tristimulus filter colorimeter or a color-difference meter.

1.2 Provision is made in this test method for the measurement of color coordinates and color differences by reflected or transmitted light using either a hemispherical optical measuring system, such as an integrating sphere, or a bidirectional optical measuring system, such as annular, circumferential, or uniplanar 45:0 and 0:45 geometry.

1.3 Because of the limited absolute accuracy of tristimulus colorimeters, this test method specifies that, when color coordinates are required, the instrument be standardized by use of a standard having similar spectral (color) and geometric characteristics to those of the specimen. This standard is also known as a product standard. The use of a product standard of suitable stability is highly desirable.

1.4 Because tristimulus colorimeters do not provide any information about the reflectance or transmittance curves of the specimens, they cannot be used to gain any information about metamerism or paramerism.

1.5 Because of the inability of tristimulus (filter) colorimeters to detect metamerism or paramerism of specimens, this test method specifies that, when color differences are required, the two specimens must have similar spectral (color) and geometric characteristics. In this case, the instrument may be standardized for reflectance measurement by use of a white reflectance standard or, for transmittance measurement, with no specimen or standard at the specimen position.

1.6 This test method is generally suitable for any non-fluorescent, planar, object-color specimens of all gloss levels. Users must determine whether an instrument complying with this method yields results that are useful to evaluate and characterize retroreflective specimens, or specimens having optical structures.

1.7 This test method does not apply to the use of a spectrocolorimeter, which is a spectrometer that provides colorimetric data, but not the underlying spectral data. Measurement by using a spectrocolorimeter is covered in Practice 1164 and methods on color measurement by spectrophotometry.

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.