ASTM_C_1257_-_15.pdf

Designation:C125715Standard Test Method forAccelerated Weathering of Solvent-Release-Type Sealants1This standard is issued under the fixed designation C1257;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 test method includes two laboratory acceleratedexposure procedures for predicting the effects of ultraviolet orultraviolet/visible radiation,heat,and moisture on color,chalking,cracking,and adhesion of solvent-release sealants.1.2 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.3 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.1.4 The committee with jurisdiction over this standard is notaware of any comparable standards published by other orga-nizations.2.Referenced Documents2.1 ASTM Standards:2C717 Terminology of Building Seals and SealantsC1442 Practice for Conducting Tests on Sealants UsingArtificial Weathering ApparatusG113 Terminology Relating to Natural and Artificial Weath-ering Tests of Nonmetallic MaterialsG151 Practice for Exposing Nonmetallic Materials inAccel-erated Test Devices that Use Laboratory Light SourcesG154 Practice for Operating Fluorescent Ultraviolet(UV)Lamp Apparatus for Exposure of Nonmetallic MaterialsG155 Practice for Operating Xenon Arc Light Apparatus forExposure of Non-Metallic Materials3.Terminology3.1 Definitions:3.1.1 Refer to Terminology C717 and G113 for definitionsof terms used in this test method:standard conditions.4.Summary of Test Method4.1 Four test specimens are prepared in U-shaped aluminumchannels.After curing,three of the specimens are exposed inthe laboratory accelerated weathering device and the fourthspecimen is stored under standard conditions as an unexposedfile specimen.At the end of the exposure period,the specimensare examined for chalking,color change,center cracking,edgecracking,and loss of adhesion versus the unexposed filespecimen.5.Significance and Use5.1 It is difficult to establish a precise correlation betweenlaboratory accelerated and natural weathering because of(1)geographical climatic variations,local weather variation fromnormal,and local pollutants and(2)the fact that the accelera-tion factor is material dependent,varying with the type ofmaterial as well as its formulation.This test method is used todetermine the resistance of a sealant to laboratory acceleratedweathering and,if a control material with known outdoorweathering performance is used,the relative weathering per-formance of the sealant against that of the control material.5.2 This test method is conducted using aluminum channels.Other substrate materials may show different results.6.Apparatus6.1 Exposure Apparatus:6.1.1 Fluorescent UV/Condensation Apparatus,that con-forms to the requirements in Practices G151 and G154 withUVA-340 type lamps.6.1.2 Xenon-Arc Apparatus,that conforms to the require-ments in Practices G151 and G155 with daylight type filters.6.2 Four-Mill Finish Aluminum U-Channels,76 mm longby 19 mm wide by 9.5 mm deep(3 by34by38in.)insidedimensions.Additional substrate materials may be specified.6.3 Steel Spatula.7.Procedure7.1 Condition sufficient compound in an original closedcontainer for at least 24 h at standard conditions.1This test method is under the jurisdiction ofASTM Committee C24 on BuildingSeals and Sealants and is the direct responsibility of Subcommittee C24.40 onWeathering.Current edition approved March 15,2015.Published April 2015.Originallyapproved in 1994.Last previous edition approved in 2012 as C1257-06a(2012).DOI:10.1520/C1257-15.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.2 Prepare four sealant test specimens in aluminumU-channels.7.2.1 Thoroughly clean channels using a suitable solventsuch as methyl ethyl ketone(MEK).Allow to dry before fillingwith sealant.7.2.2 Block the ends of the U-channels with masking tapeand overfill the entire channel with conditioned compoundfrom the bottom up being careful to avoid air entrapment.Strike the channel off flat with a spatula.Do not remove themasking tape.It is to stay in place for the entire test.Removingit may disturb the uncured or cured sealant.7.3 Cure the test specimens at standard conditions for 21days.NOTE1The producer may request conditions ot