ASTM D7356/D7356M-19

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

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.
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 1: Digital 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 are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.  
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.  
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.

General Information

• Status: Published
• Publication Date: 14-Nov-2019
• ICS: 43.040.60 - Bodies and body components
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.27 - Accelerated Testing

Relations

• Refers: ASTM G147-17 - Standard Practice for Conditioning and Handling of Nonmetallic Materials for Natural and Artificial Weathering Tests
• Effective Date: 01-Jun-2017

Standards Content (Sample)

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.
Designation: D7356/D7356M − 19
Standard Test Method for
Accelerated Acid Etch Weathering of Automotive Clearcoats
1
Using a Xenon-Arc Exposure Device
This standard is issued under the fixed designation D7356/D7356M; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This test method covers an accelerated exposure test
responsibility of the user of this standard to establish appro-
intendedtosimulatedefectsinautomotiveclearcoatscausedby
priate safety, health, and environmental practices and deter-
2
acid rain that occur at the Jacksonville, Florida exposure site.
mine the applicability of regulatory limitations prior to use.
Exterior exposures at an acid rain test location in Jacksonville,
1.6 This international standard was developed in accor-
Florida produce etch defects that range from small pits to 12.7
dance with internationally recognized principles on standard-
mm [0.5 in.] in diameter or larger acid-etched spots. The latter
ization established in the Decision on Principles for the
type of defect is not produced in other acid-etch tests that only
Development of International Standards, Guides and Recom-
produce pits that are smaller than 6.35 mm [0.25 in.] in
mendations issued by the World Trade Organization Technical
3
diameter.
Barriers to Trade (TBT) Committee.
NOTE 1—Digital images of the acid etch defects produced in outdoor
acid-rain exposures and in the accelerated test described in this test
2. Referenced Documents
method are found in Appendix X1.
4
2.1 ASTM Standards:
1.2 The accelerated test described in this test method uses a
D1293 Test Methods for pH of Water
xenon-arc light source with daylight filter conforming to the
D4517 Test Method for Low-Level Total Silica in High-
requirements of Practice G155. Specimens are sprayed with a
Purity Water by Flameless Atomic Absorption Spectros-
simulated acid rain solution and requires the use of a
copy
horizontal, flat specimen array in order to allow the acid rain
G113 Terminology Relating to Natural andArtificial Weath-
solution to remain on the test specimens for an extended period
ering Tests of Nonmetallic Materials
of time.
G147 Practice for Conditioning and Handling of Nonmetal-
1.3 There is no known ISO equivalent to this test method.
lic Materials for Natural and Artificial Weathering Tests
G151 Practice for Exposing Nonmetallic Materials inAccel-
1.4 The values stated in either SI units or inch-pound units
erated Test Devices that Use Laboratory Light Sources
are to be regarded separately as standard. The values stated in
G155 Practice for Operating XenonArc LightApparatus for
each system are not necessarily exact equivalents; therefore, to
Exposure of Non-Metallic Materials
ensure conformance with the standard, each system shall be
used independently of the other, and values from the two
3. Terminology
systems shall not be combined.
3.1 Definitions—Definitions applicable to this standard can
be found in Terminology G113.
1
This test method is under the jurisdiction of ASTM Committee D01 on Paint
3.2 Definitions of Terms Specific to This Standard:
and Related Coatings, Materials, andApplications and is the direct responsibility of
3.2.1 acid rain, n—cloud or rain droplets containing
Subcommittee D01.27 on Accelerated Testing.
pollutants, such as oxides of sulfur and nitrogen, to make them
Current edition approved Nov. 15, 2019. Published November 2019. Originally
approved in 2007. Last previous edition approved in 2013 as D7359 – 13. DOI: acidic.
10.1520/D7356_D7356M-19.
3.2.2 acid rain spots, n—spots are produced when the sun
2
The acid etch test method is covered by a patent. Interested parties are invited
evaporates standing water on the vehicle’s surface.
to submit information regarding the identification of an alternative(s) to this
patented item to ASTM International Headquarters. Your comments will receive
1
careful considerations at a meeting of the responsible technical committee, which
you may attend.
3 4
Brennan, P. J, Marino, M., Boisseau, J. and Campbell, D., Accelerated Acid For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Etch, Part II: Refined Test Procedure to ReproduceAutomotiveAcid Etch Provides contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Improved Lab Practicality and Proven Correlation,
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7356/D7356M − 13 D7356/D7356M − 19
Standard Test Method for
Accelerated Acid Etch Weathering of Automotive Clearcoats
1
Using a Xenon-Arc Exposure Device
This standard is issued under the fixed designation D7356/D7356M; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method covers an accelerated exposure test intended to simulate defects in automotive clearcoats caused by acid
2
rain 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
3
is not produced in other acid-etch tests that only produce pits that are smaller than 6.35 mm [0.25 in.] in diameter.
NOTE 1—Digital 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 are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used
independently of the other, and values from the two systems shall not be combined.
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
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
4
2.1 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
3. Terminology
3.1 Definitions—Definitions applicable to this standard can be found in Terminology G113.
3.2 Definitions of Terms Specific to This Standard:
1
This test method is under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.27 on Accelerated Testing.
Current edition approved June 1, 2013Nov. 15, 2019. Published September 2013November 2019. Originally approved in 2007. Last previous edition approved in 20072013
as D7359D7359 – 13. – 07. DOI: 10.1520/D7356_D7356M-13.10.1520/D7356_D7356M-19.
2
The acid etch test method is covered by a patent. Interested parties are invited to submit information regarding the identification of an alternative(s) to this patented item
1
to ASTM International Headquarters. Your comments will receive careful considerations at a meeting of the responsible technical committee, which you may attend.
3
Brennan, P. J, Marino, M., Boisseau, J. and Campbell, D., Accelerated Acid Etch, Part II: Refined Test Procedure to Reproduce Automotive Acid Etch Provides Improved
Lab Practicality and Proven Correlation, FSCT, 2006 FutureCoat Proceedings.
4
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annu
...