ASTM D7356 / D7356M - 13

    Standard Test Method for Accelerated Acid Etch Weathering of Automotive Clearcoats Using a Xenon-Arc Exposure Device

    Active Standard ASTM D7356 / D7356M | Developed by Subcommittee: D01.27

    Book of Standards Volume: 06.01


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    Significance and Use

    5.1 Acid etch damage is an important warranty claim item for automotive companies. As a result, acid etch resistance is an important parameter for automotive exterior coatings. The method described in this test method has been shown to simulate acid etch damage of automotive clearcoats that occurs when such coatings are exposed from May through mid-August in Jacksonville, FL.3,5 The accelerated test described in this standard allows year-round testing as opposed to the limited outdoor exposure time available for the Jacksonville, FL exposures.

    1. Scope

    1.1 This test method covers an accelerated exposure test intended to simulate defects in automotive clearcoats caused by acid rain2 that occur at the Jacksonville, Florida exposure site. Exterior exposures at an acid rain test location in Jacksonville, Florida produce etch defects that range from small pits to 12.7 mm [0.5 in.] in diameter or larger acid-etched spots. The latter type of defect is not produced in other acid-etch tests that only produce pits that are smaller than 6.35 mm [0.25 in.] in diameter.3

    Note 1Digital images of the acid etch defects produced in outdoor acid-rain exposures and in the accelerated test described in this test method are found in Appendix X1.

    1.2 The accelerated test described in this test method uses a xenon-arc light source with daylight filter conforming to the requirements of Practice G155. Specimens are sprayed with a simulated acid rain solution and requires the use of a horizontal, flat specimen array in order to allow the acid rain solution to remain on the test specimens for an extended period of time.

    1.3 There is no known ISO equivalent to this test method.

    1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

    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 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

    D1293 Test Methods for pH of Water

    D4517 Test Method for Low-Level Total Silica in High-Purity Water by Flameless Atomic Absorption Spectroscopy

    G113 Terminology Relating to Natural and Artificial Weathering Tests of Nonmetallic Materials

    G147 Practice for Conditioning and Handling of Nonmetallic Materials for Natural and Artificial Weathering Tests

    G151 Practice for Exposing Nonmetallic Materials in Accelerated Test Devices that Use Laboratory Light Sources

    G155 Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials


    ICS Code

    ICS Number Code 43.040.60 (Bodies and body components)

    UNSPSC Code

    UNSPSC Code 72153203(Corrosion control service)


    DOI: 10.1520/D7356_D7356M

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