ASTM_D_7356_-_D_7356M_-_13.pdf

Designation:D7356/D7356M13Standard Test Method forAccelerated Acid Etch Weathering of Automotive ClearcoatsUsing a Xenon-Arc Exposure Device1This standard is issued under the fixed designation D7356/D7356M;the number immediately following the designation indicates theyear of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of lastreapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This test method covers an accelerated exposure testintended to simulate defects in automotive clearcoats caused byacid rain2that 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 12.7mm 0.5 in.in diameter or larger acid-etched spots.The lattertype of defect is not produced in other acid-etch tests that onlyproduce pits that are smaller than 6.35 mm 0.25 in.indiameter.3NOTE1Digital images of the acid etch defects produced in outdooracid-rain exposures and in the accelerated test described in this testmethod are found in Appendix X1.1.2 The accelerated test described in this test method uses axenon-arc light source with daylight filter conforming to therequirements of Practice G155.Specimens are sprayed with asimulated acid rain solution and requires the use of ahorizontal,flat specimen array in order to allow the acid rainsolution to remain on the test specimens for an extended periodof 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 unitsare to be regarded separately as standard.The values stated ineach system may not be exact equivalents;therefore,eachsystem shall be used independently of the other.Combiningvalues from the two systems may result in non-conformancewith the standard.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:4D1293 Test Methods for pH of WaterD4517 Test Method for Low-Level Total Silica in High-Purity Water by Flameless Atomic Absorption Spectros-copyG113 Terminology Relating to Natural and Artificial Weath-ering Tests of Nonmetallic MaterialsG147 Practice for Conditioning and Handling of Nonmetal-lic Materials for Natural and Artificial Weathering TestsG151 Practice for Exposing Nonmetallic Materials inAccel-erated Test Devices that Use Laboratory Light SourcesG155 Practice for Operating Xenon Arc Light Apparatus forExposure of Non-Metallic Materials3.Terminology3.1 DefinitionsDefinitions applicable to this standard canbe found in Terminology G113.3.2 Definitions of Terms Specific to This Standard:3.2.1 acid rain,ncloud or rain droplets containingpollutants,such as oxides of sulfur and nitrogen,to make themacidic.3.2.2 acid rain spots,nspots are produced when the sunevaporates standing water on the vehicles surface.3.2.2.1 DiscussionThey fall into two categories,mineraldeposits and acid-etched spots.Mineral deposits are whitecalcium spots or salt deposits left on the surface after waterevaporates.These deposits can be easily removed with apre-wax cleaner(polish)or a clay bar.Acid-etched spots aredepressions in the paint or clear coat,which cannot be easilyremoved.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.27 on Accelerated Testing.Current edition approved June 1,2013.Published September 2013.Originallyapproved in 2007.Last previous edition approved in 2007 as D7359 07.DOI:10.1520/D7356_D7356M-13.2The acid etch test method is covered by a patent.Interested parties are invitedto submit information regarding the identification of an alternative(s)to thispatented item to ASTM International Headquarters.Your comments will receivecareful considerations at a meeting of the responsible technical committee,1whichyou may attend.3Brennan,P.J,Marino,M.,Boisseau,J.and Campbell,D.,Accelerated AcidEtch,Part II:Refined Test Procedure to Reproduce Automotive Acid Etch ProvidesImproved Lab Practicality and Proven Correlation,FSCT,2006 FutureCoat Pro-ceedings.4For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.Summary of Test Method4.1 The Automotive Clearcoat coating being evaluated isapplied to an automotive basecoat(typically black)that hasbeen coated onto a ste