ASTM D4138-07

    Historical Standard: ASTM D4138-07 Standard Practices for Measurement of Dry Film Thickness of Protective Coating Systems by Destructive, Cross-Sectioning Means

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    ASTM D4138

    1. Scope

    1.1 This practice describes the measurement of dry film thickness of coating films by microscopic observation of precision angular cuts in the coating film. Use of these procedures may require repair of the coating film. This practice is intended to supplement the manufacturers' instructions for the manual operation of the gages and is not intended to replace them. It includes definitions of key terms, reference documents, the significance and use of the practice, and the advantages and limitations of the instruments.

    1.2 Three procedures are provided for measuring dry film thickness of protective coating systems:

    1.2.1 Procedure AUsing groove cutting instruments.

    1.2.2 Procedure B using grinding instruments.

    1.2.3 Procedure C Using drill bit instruments.

    1.3 These procedures are not applicable for soft or ductile substrates that may deform under the test gage cutting tip. The substrate should be sufficiently rigid to prevent deformation of the coating during the cutting process. The surface may be flat or moderately curved. Pipes as small as 25 mm (1 in.) in diameter may be measured in the axial direction.

    1.4 Individual coats in a multicoat system where there is a discernible visual difference between coats or the overall thickness of a coating system can be measured by these procedures.

    1.5 The range of thickness measurement is typically 2 to 2000 microns (0.1 to 80 mils) and depends upon the cutting angle of the blade.

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

    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 determine 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

    D823 Practices for Producing Films of Uniform Thickness of Paint, Varnish, and Related Products on Test Panels

    D1005 Test Method for Measurement of Dry-Film Thickness of Organic Coatings Using Micrometers

    D7091 Practice for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to Ferrous Metals and Nonmagnetic, Nonconductive Coatings Applied to Non-Ferrous Metals


    ICS Code

    ICS Number Code 87.040 (Paints and varnishes)

    UNSPSC Code

    UNSPSC Code 46181533(Protective coats)


    DOI: 10.1520/D4138-07

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