Standard Active Last Updated: Oct 13, 2021
ASTM D7133-21

Standard Test Method for Polyurethane Raw Materials: Instrumental Measurement of Tristimulus CIELAB Color and Yellowness Index of Liquids

Significance and Use

5.1 CIELAB is a visual-based scale that is used to specify color and set color tolerances for the polyurethane industry.

5.2 Yellowness Index specifies the degree of departure of the sample from colorless towards yellow. This index is only suitable for clear liquids with degrees of saturation in yellow (dominant transmission wavelength in the 570 to 580 nm range). It is used to set tolerances for appropriate polyurethane raw materials.

5.3 This test method does not include provisions for materials with fluorescence or visible haze (usually greater than 5 % haze).

5.4 Before proceeding with this test method, make reference to the specification of the material being tested. Any test specimen preparation, conditioning, dimensions, or testing parameters or combination thereof, covered in the materials specification shall take precedence over those mentioned in this test method. If there are no material specifications, then the default conditions apply.


1.1 This test method provides an instrumental method for measuring the CIELAB color and Yellowness Index (YI) of liquid polyurethane raw materials. The CIELAB and YI results are derived from mathematical manipulation of CIE tristimulus values in accordance with Practices E308 and E313, respectively.

1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions provided for information only and are not considered standard.

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

Note 1: There is no known ISO equivalent to this standard.

1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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Book of Standards Volume: 08.03
Developed by Subcommittee: D20.22
Pages: 5
DOI: 10.1520/D7133-21
ICS Code: 83.080.20