ASTM D4086-18(2023)

Standard Practice for Visual Evaluation of Metamerism

SIGNIFICANCE AND USE
4.1 Metameric color matches result from the use of different colorants (pigments, dyes, and the like) in achieving the same color match. Usually, the purchaser requires that the color match be nonmetameric; this practice permits this requirement to be quickly tested in both field and laboratory. Where nonmetameric matches are not possible or practicable, for cost or other reasons, some limitation of metamerism may be required. The procedures for estimating the magnitude of metamerism described in this practice provide methods for assessing the effectiveness of such limitation.
SCOPE
1.1 This practice describes visual methods for detecting metamerism and for estimating the magnitude of a metameric color difference.  
1.2 The practice is limited to the consideration of illuminant metamerism and observer metamerism. This practice does not cover gonioapparent samples.  
1.3 This practice does not provide for the computation of indices of metamerism based upon instrumental measurement of spectral characteristics.  
1.4 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.  
1.5 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.

General Information

• Status: Published
• Publication Date: 31-Oct-2023
• ICS: 87.040 - Paints and varnishes
• Technical Committee: E12 - Color and Appearance
• Drafting Committee: E12.11 - Visual Methods

Relations

• Replaces: ASTM D4086-18 - Standard Practice for Visual Evaluation of Metamerism
• Effective Date: 01-Nov-2023
• Referred By: ASTM D7195-21 - Standard Guide for Setting Object Color Specifications
• Effective Date: 01-Nov-2023
• Referred By: ASTM E1499-16(2023) - Standard Guide for Selection, Evaluation, and Training of Observers
• Effective Date: 01-Nov-2023
• Referred By: ASTM D5531-17(2023) - Standard Guide for Preparation, Maintenance, and Distribution of Physical Product Standards for Color and Geometric Appearance of Coatings
• Effective Date: 01-Nov-2023
• Referred By: ASTM D3451-06(2017) - Standard Guide for Testing Coating Powders and Powder Coatings
• Effective Date: 01-Nov-2023
• Referred By: ASTM E1808-96(2021) - Standard Guide for Designing and Conducting Visual Experiments
• Effective Date: 01-Nov-2023
• Referred By: ASTM D1729-22 - Standard Practice for Visual Appraisal of Colors and Color Differences of Diffusely-Illuminated Opaque Materials
• Effective Date: 01-Nov-2023
• Referred By: ASTM D2244-23 - Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
• Effective Date: 01-Nov-2023
• Referred By: ASTM D5382-02(2017) - Standard Guide to Evaluation of Optical Properties of Powder Coatings
• Effective Date: 01-Nov-2023

Overview

ASTM D4086-18(2023) - Standard Practice for Visual Evaluation of Metamerism provides a reliable framework for visually detecting and assessing the extent of metamerism in colored samples. Metamerism occurs when two color samples appear to match under one light source but differ under another, often due to the use of different colorants such as pigments or dyes. This standard is widely referenced in industries where precise color matching is critical, enabling both field and laboratory evaluation of metameric color matches.

This ASTM standard is designed to assist manufacturers, purchasers, and quality assurance professionals in identifying and managing metamerism issues, ensuring consistency and reliability in color-critical applications. By outlining clear procedures, the standard supports decision-making when absolute nonmetameric matches are not practical.

Key Topics

• Visual Detection of Metamerism:

  • Describes straightforward methods for evaluating whether two samples are metameric using different types of illumination.
  • Recommends using light sources with distinctly different spectral characteristics (e.g., incandescent, fluorescent, and LED).
  • Suggests viewing samples under controlled environments for accurate comparison.

• Assessment of Observer Metamerism:

  • Outlines protocols for multiple observers to assess color matches, recognizing individual differences in color perception.
  • Recommends using five to ten observers to avoid bias.

• Estimation of Metameric Difference Magnitude:

  • Uses visual comparison with gray scale pairs as detailed in ASTM D2616 to estimate the severity of metameric color differences.

• Reporting Requirements:

  • Specifies the information to be included in reports, such as specimen identification, light sources used, observer details, and visually observed differences.

• Limitations:

  • The practice addresses only illuminant and observer metamerism, not instrument-based metamerism or gonioapparent samples.
  • Does not provide for the computation of metamerism indices based on instrumental spectral measurement.

Applications

This standard delivers strong practical value in various sectors where accurate color evaluation is essential:

• Paints and Coatings: Ensures batch-to-batch color consistency in automotive, architectural, and industrial finishes.
• Textiles and Apparel: Supports color specification and quality control for garments and fabrics, where metamerism can affect consumer perception.
• Plastics and Polymers: Used in visual evaluation of molded or extruded parts requiring precise color matches in end-use environments.
• Consumer Goods and Retail: Helps avoid color mismatches in products such as furniture, flooring, and decorative items under store and home lighting.
• Quality Assurance: Assists manufacturers and suppliers in meeting customer requirements for nonmetameric color matches and documenting evaluation methods.

Related Standards

Professionals using ASTM D4086-18(2023) may also reference:

• ASTM D2616: Test Method for Evaluation of Visual Color Difference With a Gray Scale, which supports standardized assessment of the degree of metamerism.
• ASTM E284: Terminology of Appearance, providing foundational definitions related to color and appearance measurements.

Using these referenced standards in conjunction, organizations can ensure robust, consistent approaches for the visual evaluation of metamerism and overall color quality management. These practices are vital for meeting both internal quality standards and customer expectations in color-critical industries.

Standards Content (Sample)

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.
Designation: D4086 − 18 (Reapproved 2023)
Standard Practice for
Visual Evaluation of Metamerism
This standard is issued under the fixed designation D4086; 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.
INTRODUCTION
Because perceived color involves the spectral characteristics of source, object, and eye, different
combinations of spectral characteristics can evoke the same color sensation. For this reason,
metamerism has been described as “invisible spectral differences.”
A pair of specimens is said to be metameric when the specimens match under one set of illuminating
and viewing conditions and do not match under another set. For this condition to exist, there must be
differences in spectral character of specimens and sources or specimens and observers. There may be
more than one condition under which the specimens match, as well as more than one for which they
are a mismatch. Similarly, two specimens may be a near-match under one set of conditions, and under
another set the direction and magnitude of the color difference may change.
1. Scope 2. Referenced Documents
1.1 This practice describes visual methods for detecting 2.1 ASTM Standards:
metamerism and for estimating the magnitude of a metameric D2616 Test Method for Evaluation of Visual Color Differ-
color difference. ence With a Gray Scale
E284 Terminology of Appearance
1.2 The practice is limited to the consideration of illuminant
metamerism and observer metamerism. This practice does not
3. Terminology
cover gonioapparent samples.
3.1 Definitions of appearance terms used in this practice
1.3 This practice does not provide for the computation of
may be found in Terminology E284.
indices of metamerism based upon instrumental measurement
3.2 Definitions:
of spectral characteristics.
3.2.1 metamerism, n—property of two specimens that match
1.4 This standard does not purport to address all of the
under a specified illuminator and to a specified observer and
safety concerns, if any, associated with its use. It is the
whose spectral reflectances or transmittances differ in the
responsibility of the user of this standard to establish appro-
visible wavelengths.
priate safety, health, and environmental practices and deter-
3.2.1.1 Discussion—As a consequence of the required
mine the applicability of regulatory limitations prior to use.
difference, the two specimens may not match under a different
1.5 This international standard was developed in accor-
illuminator or to a different observer. Similar considerations
dance with internationally recognized principles on standard-
apply to two lights matching to a specified observer but not to
ization established in the Decision on Principles for the
other observers. (E284)
Development of International Standards, Guides and Recom-
3.2.2 paramerism, n—phenomenon in which specimens
mendations issued by the World Trade Organization Technical
having different spectrophotometric curves produce approxi-
Barriers to Trade (TBT) Committee.
mately the same color sensation under the same illuminating
and viewing conditions. (E284)
This practice is under the jurisdiction of ASTM Committee E12 on Color and
Appearance and is the direct responsibility of Subcommittee E12.11 on Visual
Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2023. Published November 2023. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1982. Last previous edition approved in 2018 as D4086 – 18. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D4086-18R23. the ASTM website.
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D4086 − 18 (2023)
4. Significance and Use difference was manifested. Use is made of paired gray scales,
as specified in Test Method D2616, that display increasingly
4.1 Metameric color matches result from the use of different
larger color differences with each successive pair of grays in
colorants (pigments, dyes, and the like) in achieving the same
the scale. The metameric specimen pair is placed in juxtapo-
color match. Usually, the purchaser requires that the color
sition with the edge of the gray scale and compared with
match be nonmetameric; this practice permits this requirement
various gray pairs. The total perceived color difference be-
to be quickly tested in both field and laboratory. Where
tween the two members of the test pair is compared to the
nonmetameric matches are not possible or practicable, for cost
lightness differences of the pairs on the gray scale, and the gray
or other reasons, some limitation of metamerism may be
scale pair is selected that is the best visual equivalent to the
required. The procedures for estimating the magnitude of
color difference of the test pair following the procedures given
metamerism described in this practice provide methods for
in Test Method D2616. It is assumed, as in the Significance and
assessing the effectiveness of such limitation.
Use section in Test Method D2616, that, the total color
difference can be so evaluated in terms of an equivalent
5. Test Speci
...