ASTM_D_7869_-_13.pdf

Designation:D786913Standard Practice forXenon Arc Exposure Test with Enhanced Light and WaterExposure for Transportation Coatings1This standard is issued under the fixed designation D7869;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice specifies the operating procedures for acontrolled irradiance xenon arc light and water apparatus.Theprocedure uses one or more lamp(s)and optical filter(s)toproduce irradiance similar to sunlight in the UV and visiblerange.It also simulates the water absorption and stress cyclesexperienced by automotive exterior coatings under naturalweathering conditions.This practice has also been foundapplicable to coatings on other transportation vehicles,such asaircraft,trucks and rail cars.1.2 This practice uses a xenon arc light source with speci-fied optical filter(s).The spectral power distribution(SPD)forthe lamp and special daylight filter(s)is as specified in AnnexA1.The irradiance level used in this practice varies between0.40 and 0.80 W/(m2nm)at 340 nm.Water is sprayed on thespecimens during portions of several dark steps.The applica-tion of water is such that the coatings will absorb and desorbsubstantial amounts of water during testing.In addition,thecycling between wet/dry and warm/cool will induce mechani-cal stresses into the materials.These test conditions aredesigned to simulate the physical and chemical stresses fromenvironments in a subtropical climate,such as southernFlorida.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4 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:2D4517 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 Definitions applicable to this standard can be found inTerminology G113.3.2 transportation coatings,nexterior coatings used forvehicles subjected to natural weathering conditions such asautomobiles,aircraft,trucks,rail cars,etc.4.Summary of Practice4.1 Test specimens are exposed to specific test conditionsdesigned to simulate the physical and chemical stresses fromenvironments in a subtropical climate,such as southernFlorida.The test conditions consist of a primary test cycle anda sub-cycle.The primary test cycle includes two long waterexposures and a single,long light exposure with precisespectral match to daylight as described in Annex A1.It isdesigned to reproduce water penetration failures,such asadhesion,blistering and diffusion of small molecules(1).3Thesub-cycle consisting of shorter alternating water and light1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.27 on Accelerated Testing.Current edition approved June 1,2013.Published June 2013.DOI:10.1520/D7869-13.2For 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.3The boldface numbers in parentheses refer to the list of references at the end ofthis standard.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 exposures is designed to simulate cyclic stresses such ascracking and surface erosion.These two cycles are designed toreplicate the common types of failures driven by the interactionof photo-oxidation during daylight and hydrolysis during waterexposure that are seen in a subtropical climate such as glossloss,color change,adhesion,blistering and cracking(2).5.Significance and Use5.1 This test procedure is used to simulate the physical andenvironmental stresses that a coating for exterior transportationapplications(for example,automotive)is exposed to in asubtropical climate,such as southern Florida.It has been foundthat such a subtropical climate causes particularly severedeterioration of such coatings.The long water exposures andwet/dry cycling found in so