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    ASTM D6441 - 05(2016)

    Standard Test Methods for Measuring the Hiding Power of Powder Coatings

    Active Standard ASTM D6441 | Developed by Subcommittee: D01.51

    Book of Standards Volume: 06.02

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    Significance and Use

    5.1 Contrast ratio at a specified film thickness is a useful hiding power parameter for production control and purchasing specifications.

    5.2 The greater the hiding power, the less coating is required per unit area to obtain adequate hiding. Knowledge of hiding power is therefore important in regard to coating costs and for comparing coating value.

    1. Scope

    1.1 These test methods determine and report the hiding power of a powder coating with respect to two parameters:

    1.1.1 Test Method A—Contrast Ratio at a given film thickness

    1.1.2 Test Method B—Film thickness at 0.98 (98 %) contrast ratio.

    Note 1: The measured parameters follow powder coating industry practice by measuring hiding power in relation to film thickness, rather than the “Spreading Rate” function employed in Test Methods D344 and D2805 and other hiding power test methods.

    Note 2: Hiding power is photometrically defined as the spreading rate at 0.98 contrast ratio. See definitions of spreading rate and hiding power in Terminology D16, D2805, and the Paint and Coatings Testing Manual.

    Note 3: The contrast ratio 0.98 is conventionally accepted in the coatings industry as representing “complete” hiding for reflectometric hiding power measurements. But visually, as well as photometrically, it is slightly less than complete.

    1.2 These test methods cover the determination of the hiding power of powder coatings applied by electrostatic spraying.

    1.3 These test methods determine hiding power by means of reflectometric and thickness gage measurements. They are limited to coatings having a minimum CIE-Y reflectance of 15 %.

    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 and health practices, and to determine in advance the applicability of regulatory limitations prior to use.

    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

    D16 Terminology for Paint, Related Coatings, Materials, and Applications

    D344 Test Method for Relative Hiding Power of Paints by the Visual Evaluation of Brushouts

    D2805 Test Method for Hiding Power of Paints by Reflectometry

    D3451 Guide for Testing Coating Powders and Powder Coatings

    E284 Terminology of Appearance

    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

    ICS Code

    ICS Number Code 87.040 (Paints and varnishes)

    UNSPSC Code

    UNSPSC Code 31211708(Powder coat)

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

    DOI: 10.1520/D6441-05R16

    Citation Format

    ASTM D6441-05(2016), Standard Test Methods for Measuring the Hiding Power of Powder Coatings, ASTM International, West Conshohocken, PA, 2016, www.astm.org

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