ASTM E3040-22 PDF

Full title and description

Standard Practice for Evaluation of Instrumental Color Difference with a Gray Scale — ASTM designation E3040-22. This practice describes a procedure for converting instrumentally measured color differences between a test specimen and an untreated or original specimen into a conventional gray-scale rating for change in color, using spectrophotometric measurements and defined calculation steps.

Abstract

ASTM E3040-22 provides a repeatable practice for evaluating instrumentally measured color differences and expressing the severity of color change on a gray scale. The method measures the colors of a test specimen and a reference specimen using spectrophotometry, computes color-difference coordinates, and converts those numerical differences to a gray-scale rating through a series of calculations and decision criteria. The practice is intended to align instrumental assessment with conventional visual gray-scale evaluations used in industries such as coatings, textiles, printing, and color quality control.

General information

• Status: Active (current edition approved June 1, 2022).
• Publication date: June 1, 2022 (E3040-22).
• Publisher: ASTM International.
• ICS / categories: 17.180.20 (Colours and measurement of light).
• Edition / version: E3040-22 (current 2022 edition; previous edition E3040-18).
• Number of pages: 5 pages.

Scope

This practice applies to the instrumental evaluation of color change by: (1) measuring the color coordinates of a specimen that has undergone a change and an untreated or original specimen using spectrophotometric techniques; (2) calculating conventional color-difference attributes from the instrumental data; and (3) converting those calculated differences to a gray-scale rating that corresponds to visual gray-scale assessments of color change. It is intended for use where an objective, instrument-based gray-scale evaluation is required or preferred over direct visual appraisal.

Key topics and requirements

• Definitions and terminology relevant to appearance and color measurement (references to ASTM color/appearance terminology).
• Requirements for spectrophotometric measurement of both test and reference specimens (instrument conditions, geometry, and measurement procedures).
• Procedures for calculating color-difference values from measured coordinates (conversion to conventional color-difference attributes).
• Algorithm or series of calculations to convert numeric color differences into a gray-scale rating for color change.
• Reporting and documentation recommendations to support traceability and comparability of results.
• Normative references to related ASTM practices and test methods used for color measurement and gray-scale visual evaluation.

Typical use and users

Typical users include color scientists, quality-control laboratories, textile and coatings manufacturers, printers, instrument manufacturers, and testing organizations that require objective, instrument-based assessments of color change that map to traditional gray-scale visual ratings. The practice is used in product development, incoming/outgoing inspection, accelerated weathering and exposure testing, and comparative color evaluations.

Related standards

ASTM E3040-22 references and is used alongside related ASTM standards and practices for color and appearance, commonly including D2616 (visual gray scale for color difference), D2244 (calculation of color differences), E284 (terminology of appearance), and E1164 (obtaining spectrometric data for objects). Users often apply these standards together to establish both visual and instrumental evaluation chains.

Keywords

color difference, gray scale, instrumental evaluation, spectrophotometry, color measurement, E3040-22, color change, appearance, color tolerance.

FAQ

Q: What is this standard?

A: ASTM E3040-22 is a standard practice that defines how to evaluate instrumentally measured color differences and express them as a gray-scale rating for color change. It connects spectrophotometric color-difference data to the conventional gray-scale visual assessment.

Q: What does it cover?

A: It covers measurement requirements, calculation methods for converting measured color coordinates to color-difference attributes, and the conversion procedure that maps those numerical differences to a gray-scale rating for change in color. It does not replace visual assessment when that is required, but provides an objective instrument-based alternative or complement.

Q: Who typically uses it?

A: Laboratories, quality-control personnel, color scientists, textile and coatings manufacturers, printing and packaging sectors, instrument suppliers, and standards users who need reproducible, instrument-based color-change ratings.

Q: Is it current or superseded?

A: The current edition is E3040-22, approved June 1, 2022. The previous edition was E3040-18. As published in 2022, E3040-22 is the active edition. Users should verify with ASTM or their standards subscription for any amendments or reapprovals after 2022.

Q: Is it part of a series?

A: E3040 is part of ASTM Committee E12 (Color and Appearance) work products and is typically used together with other E12 standards and related test methods (for example D2616, D2244, E284, and E1164) to form a comprehensive approach to color measurement and evaluation.

Q: What are the key keywords?

A: Color difference, gray scale, spectrophotometry, instrumental color measurement, color change, color tolerance, ASTM E3040-22.