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    ASTM D6290 - 19

    Standard Test Method for Color Determination of Plastic Pellets

    Active Standard ASTM D6290 | Developed by Subcommittee: D20.40

    Book of Standards Volume: 08.03

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    Significance and Use

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

    Note 2: Some materials, such as polyamide (nylon), can be cooled very differently during the production of the pellets. This variation in the cooling of the pellets can result in different levels of crystallinity in the pellets only. More crystalline nylons will be more opaque than amorphous nylons. This will result in differences in pellet opacity. The pellet shape is independent of the crystallinity of the material. This variation in pellet appearance, due to varying levels of crystallinity, does not affect final properties.

    Note 3: This test method should not be used for general material specifications.

    4.2 This test method describes a technique useful for making color comparisons of resins in pellet form that is fast and convenient as it does not require preparation, such as molding or extruding specimens. The test method shall be used only to compare specimens of similar pellet shape, size, texture, and degree of translucency. For example, compare translucent disc-shaped pellets to translucent disc-shaped pellets, not with opaque, rectangular shaped pellets.

    4.3 Exact measurements of resin pellet color are not necessarily directly related to the color of the final cast, molded or extruded product due to the multitude of variables, such as producing variables, methods, and pellet shape and size. Color measurements can be useful for comparing resins in pellet form when all samples are similar in shape and size.

    4.4 A three-number tristimulus system is necessary to quantify color completely and precisely. The general method used in this procedure measures color using the CIE Systems described in Practice E308, Test Method D2244, the CIE 1976 (X, Y, Z) system, and, the CIELAB 1976 color space.3

    4.5 Individual components of the tristimulus measurement such as CIE Y (Luminance), Hunter L, a, b, or CIE L*, a*, b* values or other useful metrics like yellowness index in accordance with Practice E313 can be used to describe color attributes of materials.

    1. Scope

    1.1 This test method is used for the instrumental measurement of the degree of yellowness (or change of degree of yellowness) under daylight illumination of homogeneous, nonfluorescent, nearly-colorless transparent or nearly-white translucent or opaque plastics. The measurement is made on pellets and based on tristimulus values obtained with a spectrophotometer or colorimeter.

    1.2 This test method is applicable to the color analysis of plastic pellets. It is possible that each material will have unique characteristics that determine the color values.

    1.3 This procedure outlines a method to determine color measurements, such as Yellowness Index (YI), CIE X, Y, Z, and Hunter L, a, b, or CIE L*, a*, b*.

    1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

    1.5 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: This standard and ISO 17223 address the same subject matter but differ in technical content.

    1.6 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 (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    D883 Terminology Relating to Plastics

    D2244 Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates

    E179 Guide for Selection of Geometric Conditions for Measurement of Reflection and Transmission Properties of Materials

    E284 Terminology of Appearance

    E308 Practice for Computing the Colors of Objects by Using the CIE System

    E313 Practice for Calculating Yellowness and Whiteness Indices from Instrumentally Measured Color Coordinates

    E456 Terminology Relating to Quality and Statistics

    E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

    E1331 Test Method for Reflectance Factor and Color by Spectrophotometry Using Hemispherical Geometry

    E1347 Test Method for Color and Color-Difference Measurement by Tristimulus Colorimetry

    E1349 Test Method for Reflectance Factor and Color by Spectrophotometry Using Bidirectional (45:0 or 0:45) Geometry

    E2935 Practice for Conducting Equivalence Testing in Laboratory Applications

    ISO/IEC Standards

    CIE Standard D001

    ISO17223 Plastics Determination of Yellowness Index and Change in Yellowness Index.

    ICS Code

    ICS Number Code 17.180.20 (Colours and measurement of light); 83.080.01 (Plastics in general)

    UNSPSC Code

    UNSPSC Code 13102000(Thermoplastic plastics)

    Referencing This Standard
    Link Here
    Link to Active (This link will always route to the current Active version of the standard.)

    DOI: 10.1520/D6290-19

    Citation Format

    ASTM D6290-19, Standard Test Method for Color Determination of Plastic Pellets, ASTM International, West Conshohocken, PA, 2019, www.astm.org

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