ASTM E3040-22

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it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
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Designation: E3040 − 18 E3040 − 22
Standard Practice for
Evaluation of Instrumental Color Difference with a Gray
Scale
This standard is issued under the fixed designation E3040; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 Test Method D2616 describes a painted gray scale and the procedure to be used in the visual evaluation of color differences
on non-self-luminous materials by comparison to this scale. This practice provides an alternative method of obtaining a similarly
valued result by an instrumental method.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard, except
that the test results of this test method are converted by the calculations to an arbitrary visual scale defined by Test Method D2616,
whose units are called GS (Gray Scale for Change in Color).
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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.
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.
2. Referenced Documents
2.1 ASTM Standards:
D2244 Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
D2616 Test Method for Evaluation of Visual Color Difference With a Gray Scale
E284 Terminology of Appearance
E308 Practice for Computing the Colors of Objects by Using the CIE System
E1164 Practice for Obtaining Spectrometric Data for Object-Color Evaluation
2.2 ISO Standards:
ISO 105-A05 Textiles—Tests for Colorfastness—Part A05 Instrumental assessment of change in colour for determination of
grey scale rating
2.3 AATCC Standards:
AATCC Evaluation Procedure 7 Instrumental Assessment of the Change in Color of a Test Specimen
This practice is under the jurisdiction of ASTM Committee E12 on Color and Appearance and is the direct responsibility of Subcommittee E12.04 on Color and
Appearance Analysis.
Current edition approved March 1, 2018June 1, 2022. Published April 2018June 2022. Originally approved in 2015. Last previous edition approved in 20162018 as
E3040E3040 – 18. – 16. DOI: 10.1520/E3040-18.10.1520/E3040-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available from American Association of Textile Chemists and Colorists (AATCC), P.O. Box 12215, Research Triangle Park, NC 27709-2215, http://www.aatcc.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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2.4 JIS Standards:
JIS L 0809 Instrumental determination of colour fastness — Change in colour and staining
3. Terminology
3.1 Definitions:
3.1.1 Definitions of appearance terms in Terminology E284 are applicable to this test method.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 color change, n—a change in color of any kind whether in lightness, hue, or chroma or any combination of these, discernible
by comparing the test specimen with a corresponding untested specimen.
3.2.2 gray scale grade, GS , n—for color change, the numerical value that is assigned to the change in color of a test specimen
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as compared to an original or untreated specimen.
4. Summary of Test Method
4.1 The color of a specimen that has been submitted to a test whose severity is evaluated by change in color, and an identical
untreated specimen, are measured spectrophotometrically and both of their colors evaluated by conventional means. The
conventional color difference attributes are converted to a Gray Scale for Color Change by a series of calculations.
4.2 This practice is similar to the following three international methods: AATCC Evaluation Procedure 7, ISO 105-A05, and JIS
L 0809.
5. Significance and Use
5.1 The gray scale grade GS is useful to evaluate the color difference of any pair of colors that have been subjected to a test whose
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severity of result is nominated by color difference of the treated member to the untreated member. This includes, but is not limited
to, scrub tests, exterior exposures, crocking tests, blocking tests, certain abrasion tests, and color transfer tests.
5.2 A major advantage of the instrumental method of obtaining gray scale grades is that under the visual method substantial
screening and training of the operators in visual color assessment is required. No such burden is placed on the operators in this
instrumental method.
5.3 The method is usually not used for staining tests which have their own gray scale for staining.
6. Apparatus
6.1 Spectrophotometer, having one of the three qualified geometries that are listed in Practice E1164. These geometries include:
bidirectional (more familiarly called 0°/45° or 45°/0°), or hemispherical specular included, or hemispherical specular excluded
geometries.
6.2 In the absence of any reason for choosing one over the other, hemispherical specular included geometry is most appropriate
for the type of measurements that are made in connection with this standard.
7. Sampling, Test Specimens, and Test Units
7.1 The specimen pairs used in this practice are nearly always a pair of identical specimens where one member of the pair has
been subjected to a test whose severity of result may be quantified by a change in color.
7.2 The practice is based upon a visual method D2616 of assessing the degree of this color change. The precision of the visual
method is such that the gray scale grade is reported to the nearest half-unit on a scale of five to one. This method is designed to
emulate the results of Test Method D2616 and as such is reported in these same half-units.
Available from Japanese Standards Association (JSA), Mita MT Bldg., 3-13-12 Mita, Minato-ku, Tokyo 108-0073, Japan, http://www.jsa.or.jp.
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8. Calibration and Standardization
8.1 Maintain the spectrophotometer in a state of calibration. Standardize the spectrophotometer in accordance with the
manufacturer’s instructions, or follow the standardization practices of Practice E1164.
9. Procedure
9.1 Measure the color of the reference specimen and calculate the CIELAB L*, a*, b*, C* and h values using the data for the 10°
observer and for illuminant D65.
9.2 Measure the color of the test specimen which has been subjected to the colorfastness test and make the same colorimetric
calculations as done for the reference specimen. Then make the calculations as described in Annex A1.
10. Calculation or Interpretation of Results
10.1 A complete description of the calculations, the symbols and subscripts used in them, is given in Annex A1 of this method.
10.2 The resul
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