ASTM D3359 Adhesion tape test

StandardTestMethodsfor

MeasuringAdhesionbyTapeTest1ThisstandardisissuedunderthefixeddesignationD3359;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheDepartmentofDefense.

1.Scope

1.1Thesetestmethodscoverproceduresforassessingtheadhesionofcoatingfilmstometallicsubstratesbyapplyingandremovingpressure-sensitivetapeovercutsmadeinthefilm.1.2TestMethodAisprimarilyintendedforuseatjobsiteswhileTestMethodBismoresuitableforuseinthelaboratory.Also,TestMethodBisnotconsideredsuitableforfilmsthickerthan5mils(125µm).

NOTE1—Subjecttoagreementbetweenthepurchaserandtheseller,TestMethodBcanbeusedforthickerfilmsifwiderspacedcutsareemployed.

1.3Thesetestmethodsareusedtoestablishwhethertheadhesionofacoatingtoasubstrateisatagenerallyadequatelevel.Theydonotdistinguishbetweenhigherlevelsofadhesionforwhichmoresophisticatedmethodsofmeasure-mentarerequired.

NOTE2—Itshouldberecognizedthatdifferencesinadherabilityofthecoatingsurfacecanaffecttheresultsobtainedwithcoatingshavingthesameinherentadhesion.

RelatedCoatingProducts2D823PracticesforProducingFilmsofUniformThicknessofPaint,Varnish,andRelatedProductsonTestPanels2D1000TestMethodForPressure-SensitiveAdhesive-CoatedTapesUsedforElectricalandElectronicApplica-tions3D1730PracticesforPreparationofAluminumandAluminum-AlloySurfacesforPainting4D2092GuideforPreparationofZinc-Coated(Galvanized)SteelSurfacesforPainting5D2370TestMethodforTensilePropertiesofOrganicCoatings2D3330TestMethodforPeelAdhesionofPressure-SensitiveTape6D3924SpecificationforStandardEnvironmentforCondi-tioningandTestingPaint,Varnish,Lacquer,andRelatedMaterials2D4060TestMethodforAbrasionResistanceofOrganicCoatingsbytheTaberAbraser23.SummaryofTestMethods

3.1TestMethodA—AnX-cutismadethroughthefilmtothesubstrate,pressure-sensitivetapeisappliedoverthecutandthenremoved,andadhesionisassessedqualitativelyonthe0to5scale.

3.2TestMethodB—Alatticepatternwitheithersixorelevencutsineachdirectionismadeinthefilmtothesubstrate,pressure-sensitivetapeisappliedoverthelatticeandthenremoved,andadhesionisevaluatedbycomparisonwithdescriptionsandillustrations.

4.SignificanceandUse

4.1Ifacoatingistofulfillitsfunctionofprotectingordecoratingasubstrate,itmustadheretoitfortheexpectedservicelife.Becausethesubstrateanditssurfacepreparation(orlackofit)haveadrasticeffectontheadhesionofcoatings,amethodtoevaluateadhesionofacoatingtodifferentsubstratesorsurfacetreatments,orofdifferentcoatingstothe

231.4Inmulticoatsystemsadhesionfailuremayoccurbe-tweencoatssothattheadhesionofthecoatingsystemtothesubstrateisnotdetermined.

1.5ThevaluesstatedinSIunitsaretoberegardedasthestandard.Thevaluesgiveninparenthesesareforinformationonly.

1.6Thisstandarddoesnotpurporttoaddressthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimitationspriortouse.

2.ReferencedDocuments2.1ASTMStandards:

D609PracticeforPreparationofCold-RolledSteelPanelsforTestingPaint,Varnish,ConversionCoatings,and

ThesetestmethodsareunderthejurisdictionofASTMCommitteeD01onPaintandRelatedCoatings,Materials,andApplicationsandarethedirectresponsibilityofSubcommitteeD01.23onPhysicalPropertiesofAppliedPaintFilms.

CurrenteditionapprovedAug.10,2002.PublishedOctober2002.OriginallypublishedasD3359–74.LastpreviouseditionD3359–97.

1AnnualAnnual4Annual5Annual6AnnualBookBookBookBookBookofofofofofASTMASTMASTMASTMASTMStandards,Standards,Standards,Standards,Standards,VolVolVolVolVol06.01.10.01.02.05.06.02.15.09.

Copyright©ASTMInternational,100BarrHarborDrive,POBoxC700,WestConshohocken,PA19428-2959,UnitedStates.

1Copyright by ASTM Int'l (all rights reserved);Reproduction authorized per License Agreement with (Turkish Standards Institute); Fri Feb 10 07:29:19 EST 2006samesubstrateandtreatment,isofconsiderableusefulnessintheindustry.

4.2Thelimitationsofalladhesionmethodsandthespecificlimitationofthistestmethodtolowerlevelsofadhesion(see1.3)shouldberecognizedbeforeusingit.Theintra-andinter-laboratoryprecisionofthistestmethodissimilartootherwidely-acceptedtestsforcoatedsubstrates(forexample,TestMethodD2370andTestMethodD4060),butthisispartlytheresultofitbeinginsensitivetoallbutlargedifferencesinadhesion.Thelimitedscaleof0to5wasselecteddeliberatelytoavoidafalseimpressionofbeingsensitive.

TESTMETHODA—X-CUTTAPETEST

5.ApparatusandMaterials

5.1CuttingTool—Sharprazorblade,scalpel,knifeorothercuttingdevices.Itisofparticularimportancethatthecuttingedgesbeingoodcondition.

5.2CuttingGuide—Steelorotherhardmetalstraightedgetoensurestraightcuts.

5.3Tape—25-mm(1.0-in.)widesemitransparentpressure-sensitivetape7withanadhesionstrengthagreeduponbythesupplierandtheuserisneeded.Becauseofthevariabilityinadhesionstrengthfrombatch-to-batchandwithtime,itisessentialthattapefromthesamebatchbeusedwhentestsaretoberunindifferentlaboratories.Ifthisisnotpossiblethetestmethodshouldbeusedonlyforrankingaseriesoftestcoatings.

5.4RubberEraser,ontheendofapencil.

5.5Illumination—Alightsourceishelpfulindeterminingwhetherthecutshavebeenmadethroughthefilmtothesubstrate.

6.TestSpecimens

6.1Whenthistestmethodisusedinthefield,thespecimenisthecoatedstructureorarticleonwhichtheadhesionistobeevaluated.

6.2Forlaboratoryuseapplythematerialstobetestedtopanelsofthecompositionandsurfaceconditionsonwhichitisdesiredtodeterminetheadhesion.

NOTE3—ApplicabletestpaneldescriptionandsurfacepreparationmethodsaregiveninPracticeD609andPracticesD1730andD2092.NOTE4—CoatingsshouldbeappliedinaccordancewithPracticeD823,orasagreeduponbetweenthepurchaserandtheseller.

NOTE5—Ifdesiredorspecified,thecoatedtestpanelsmaybesubjectedtoapreliminaryexposuresuchaswaterimmersion,saltspray,orhighhumiditybeforeconductingthetapetest.Theconditionsandtimeofexposurewillbegovernedbyultimatecoatinguseorshallbeagreeduponbetweenthepurchaserandseller.

7.Procedure

7.1Selectanareafreeofblemishesandminorsurfaceimperfections.Fortestsinthefield,ensurethatthesurfaceis

7Permacel99,manufacturedbyPermacel,NewBrunswick,NJ003,andavailablefromvariousPermaceltapedistributors,isreportedtobesuitableforthispurpose.Themanufacturerofthistapeandthemanufacturerofthetapeusedintheinterlaboratorystudy(seeRR:D01-1008),haveadvisedthissubcommitteethatthepropertiesofthesetapeswerechanged.Usersofitshould,therefore,checkwhethercurrentmaterialgivescomparableresultstoprevioussuppliedmaterial.

cleananddry.Extremesintemperatureorrelativehumiditymayaffecttheadhesionofthetapeorthecoating.

7.1.1Forspecimenswhichhavebeenimmersed:Afterimmersion,cleanandwipethesurfacewithanappropriatesolventwhichwillnotharmtheintegrityofthecoating.Thendryorpreparethesurface,orboth,asagreeduponbetweenthepurchaserandtheseller.

7.2Maketwocutsinthefilmeachabout40mm(1.5in.)longthatintersectneartheirmiddlewithasmallerangleofbetween30and45°.Whenmakingtheincisions,usethestraightedgeandcutthroughthecoatingtothesubstrateinonesteadymotion.

7.3Inspecttheincisionsforreflectionoflightfromthemetalsubstratetoestablishthatthecoatingfilmhasbeenpenetrated.IfthesubstratehasnotbeenreachedmakeanotherXinadifferentlocation.Donotattempttodeepenapreviouscutasthismayaffectadhesionalongtheincision.

7.4Removetwocompletelapsofthepressure-sensitivetapefromtherollanddiscard.Removeanadditionallengthatasteady(thatis,notjerked)rateandcutapieceabout75mm(3in.)long.

7.5Placethecenterofthetapeattheintersectionofthecutswiththetaperunninginthesamedirectionasthesmallerangles.Smooththetapeintoplacebyfingerintheareaoftheincisionsandthenrubfirmlywiththeeraserontheendofapencil.Thecolorunderthetransparenttapeisausefulindicationofwhengoodcontacthasbeenmade.

7.6Within90630sofapplication,removethetapebyseizingthefreeendandpullingitoffrapidly(notjerked)backuponitselfatasclosetoanangleof180°aspossible.

7.7InspecttheX-cutareaforremovalofcoatingfromthesubstrateorpreviouscoatingandratetheadhesioninaccor-dancewiththefollowingscale:

5ANopeelingorremoval,

4ATracepeelingorremovalalongincisionsorattheirintersection,

3AJaggedremovalalongincisionsupto1.6mm(1⁄16in.)oneitherside,2AJaggedremovalalongmostofincisionsupto3.2mm(1⁄8in.)oneitherside,

1ARemovalfrommostoftheareaoftheXunderthetape,and0A

RemovalbeyondtheareaoftheX.

7.8Repeatthetestintwootherlocationsoneachtestpanel.Forlargestructuresmakesufficientteststoensurethattheadhesionevaluationisrepresentativeofthewholesurface.7.9Aftermakingseveralcutsexaminethecuttingedgeand,ifnecessary,removeanyflatspotsorwire-edgebyabradinglightlyonafineoilstonebeforeusingagain.Discardcuttingtoolsthatdevelopnicksorotherdefectsthattearthefilm.8.Report

8.1Reportthenumberoftests,theirmeanandrange,andforcoatingsystems,wherethefailureoccurredthatis,betweenfirstcoatandsubstrate,betweenfirstandsecondcoat,etc.8.2Forfieldtestsreportthestructureorarticletested,thelocationandtheenvironmentalconditionsatthetimeoftesting.

8.3Fortestpanelsreportthesubstrateemployed,thetypeofcoating,themethodofcure,andtheenvironmentalconditionsatthetimeoftesting.

8.4IftheadhesionstrengthofthetapehasbeendeterminedinaccordancewithTestMethodsD1000orD3330,reportthe

resultswiththeadhesionrating(s).Iftheadhesionstrengthofthetapehasnotbeendetermined,reportthespecifictapeusedanditsmanufacturer.

8.5Ifthetestisperformedafterimmersion,reportimmer-sionconditionsandmethodofsamplepreparation.

9.PrecisionandBias.1Inaninterlaboratorystudyofthistestmethodinwhichoperatorsinsixlaboratoriesmadeoneadhesionmeasurementonthreepanelseachofthreecoatingscoveringawiderangeofadhesion,thewithin-laboratoriesstandarddeviationwasfoundtobe0.33andthebetween-laboratories0.44.Basedonthesestandarddeviations,thefollowingcriteriashouldbeusedforjudgingtheacceptabilityofresultsatthe95%confidencelevel:

9.1.1Repeatability—Providedadhesionisuniformoveralargesurface,resultsobtainedbythesameoperatorshouldbeconsideredsuspectiftheydifferbymorethan1ratingunitfortwomeasurements.

9.1.2Reproducibility—Tworesults,eachthemeanoftrip-licates,obtainedbydifferentoperatorsshouldbeconsideredsuspectiftheydifferbymorethan1.5ratingunits.

9.2Biascannotbeestablishedforthesetestmethods.

TESTMETHODB—CROSS-CUTTAPETEST10.ApparatusandMaterials

10.1CuttingTool9—Sharprazorblade,scalpel,knifeorothercuttingdevicehavingacuttingedgeanglebetween15and30°thatwillmakeeitherasinglecutorseveralcutsatonce.Itisofparticularimportancethatthecuttingedgeoredgesbeingoodcondition.

10.2CuttingGuide—Ifcutsaremademanually(asopposedtoamechanicalapparatus)asteelorotherhardmetalstraight-edgeortemplatetoensurestraightcuts.

10.3Rule—Temperedsteelrulegraduatedin0.5mmformeasuringindividualcuts.

10.4Tape,asdescribedin5.3.

10.5RubberEraser,ontheendofapencil.10.6Illumination,asdescribedin5.5.

10.7MagnifyingGlass—Anilluminatedmagnifiertobeusedwhilemakingindividualcutsandexaminingthetestarea.11.TestSpecimens

11.1TestspecimensshallbeasdescribedinSection6.Itshouldbenoted,however,thatmultitipcutters10providegoodresultsonlyontestareassufficientlyplanethatallcuttingedgescontactthesubstratetothesamedegree.Checkforflatnesswithastraightedgesuchasthatofthetemperedsteelrule(10.3).

8SupportingdataareavailablefromASTMInternationalHeadquarters.RequestRR:D01–1008.9Multibladecuttersareavailablefromafewsourcesthatspecializeintestingequipmentforthepaintindustry.Onesupplierthathasassistedintherefinementofthesemethodsisgiveninfootnote10.10ThesolesourceofsupplyofthemultitipcutterforcoatedpipesurfacesknowntothecommitteeatthistimeisPaulN.GardnerCo.,316NEFirstSt.,PompanoBeach,FL33060.Ifyouareawareofalternativesuppliers,pleaseprovidethisinformationtoASTMInternationalHeadquarters.Yourcommentswillreceivecarefulconsiderationatameetingoftheresponsibletechnicalcommittee,1whichyoumayattend.

12.Procedure

12.1Whererequiredorwhenagreedupon,subjectthespecimenstoapreliminarytestbeforeconductingthetapetest(seeNote3).Afterdryingortestingthecoating,conductthetapetestatroomtemperatureasdefinedinSpecificationD3924,unlessD3924standardtemperatureisrequiredoragreed.

12.1.1Forspecimenswhichhavebeenimmersed:Afterimmersion,cleanandwipethesurfacewithanappropriatesolventwhichwillnotharmtheintegrityofthecoating.Thendryorpreparethesurface,orboth,asagreeduponbetweenthepurchaserandtheseller.

12.2Selectanareafreeofblemishesandminorsurfaceimperfections,placeonafirmbase,andundertheilluminatedmagnifier,makeparallelcutsasfollows:

12.2.1Forcoatingshavingadryfilmthicknessuptoandincluding2.0mils(50µm)spacethecuts1mmapartandmakeelevencutsunlessotherwiseagreedupon.

12.2.2Forcoatingshavingadryfilmthicknessbetween2.0mils(50µm)and5mils(125µm),spacethecuts2mmapartandmakesixcuts.Forfilmsthickerthan5milsuseTestMethodA.1112.2.3Makeallcutsabout20mm(3⁄4in.)long.Cutthroughthefilmtothesubstrateinonesteadymotionusingjustsufficientpressureonthecuttingtooltohavethecuttingedgereachthesubstrate.Whenmakingsuccessivesinglecutswiththeaidofaguide,placetheguideontheuncutarea.

12.3Aftermakingtherequiredcutsbrushthefilmlightlywithasoftbrushortissuetoremoveanydetachedflakesorribbonsofcoatings.

12.4Examinethecuttingedgeand,ifnecessary,removeanyflatspotsorwire-edgebyabradinglightlyonafineoilstone.Maketheadditionalnumberofcutsat90°toandcenteredontheoriginalcuts.

12.5Brushtheareaasbeforeandinspecttheincisionsforreflectionoflightfromthesubstrate.Ifthemetalhasnotbeenreachedmakeanothergridinadifferentlocation.

12.6Removetwocompletelapsoftapeanddiscard.Re-moveanadditionallengthatasteady(thatis,notjerked)rateandcutapieceabout75mm(3in.)long.

12.7Placethecenterofthetapeoverthegridandintheareaofthegridsmoothintoplacebyafinger.Toensuregoodcontactwiththefilmrubthetapefirmlywiththeeraserontheendofapencil.Thecolorunderthetapeisausefulindicationofwhengoodcontacthasbeenmade.

12.8Within90630sofapplication,removethetapebyseizingthefreeendandrapidly(notjerked)backuponitselfatasclosetoanangleof180°aspossible.

12.9Inspectthegridareaforremovalofcoatingfromthesubstrateorfromapreviouscoatingusingtheilluminatedmagnifier.RatetheadhesioninaccordancewiththefollowingscaleillustratedinFig.1:

11TestMethodBhasbeenusedsuccessfullybysomepeopleoncoatingsgreaterthan5mils(0.13mm)byspacingthecuts5mmapart.However,theprecisionvaluesgivenin14.1donotapplyastheyarebasedoncoatingslessthan5mm(0.13mm)inthickness.

5BTheedgesofthecutsarecompletelysmooth;noneofthesquaresofthelatticeisdetached.

4BSmallflakesofthecoatingaredetachedatintersections;lessthan5%oftheareaisaffected.

3BSmallflakesofthecoatingaredetachedalongedgesandatintersec-tionsofcuts.Theareaaffectedis5to15%ofthelattice.

2BThecoatinghasflakedalongtheedgesandonpartsofthesquares.Theareaaffectedis15to35%ofthelattice.

1B

Thecoatinghasflakedalongtheedgesofcutsinlargeribbonsandwholesquareshavedetached.Theareaaffectedis35to65%ofthelattice.

0B

FlakinganddetachmentworsethanGrade1.

12.10Repeatthetestintwootherlocationsoneachtestpanel.

13.Report

13.1Reportthenumberoftests,theirmeanandrange,andforcoatingsystems,wherethefailureoccurred,thatis,betweenfirstcoatandsubstrate,betweenfirstandsecondcoat,etc.

13.2Reportthesubstrateemployed,thetypeofcoatingandthemethodofcure.

13.3Iftheadhesionstrengthhasbeendeterminedinaccor-dancewithTestMethodsD1000orD3330,reporttheresultswiththeadhesionrating(s).Iftheadhesionstrengthofthetapehasnotbeendetermined,reportthespecifictapeusedanditsmanufacturer.

13.4Ifthetestisperformedafterimmersion,reportimmer-sionconditionsandmethodofsamplepreparation.

14.PrecisionandBias814.1Onthebasisoftwointerlaboratorytestsofthistestmethodinoneofwhichoperatorsinsixlaboratoriesmadeoneadhesionmeasurementonthreepanelseachofthreecoatingscoveringawiderangeofadhesionandintheotheroperatorsinsixlaboratoriesmadethreemeasurementsontwopanelseachoffourdifferentcoatingsappliedovertwoothercoatings,thepooledstandarddeviationsforwithin-andbetween-laboratorieswerefoundtobe0.37and0.7.Basedonthesestandarddeviations,thefollowingcriteriashouldbeusedforjudgingtheacceptabilityofresultsatthe95%confidencelevel:

14.1.1Repeatability—Providedadhesionisuniformoveralargesurface,resultsobtainedbythesameoperatorshouldbeconsideredsuspectiftheydifferbymorethanoneratingunitfortwomeasurements.

FIG.1ClassificationofAdhesionTestResults

14.1.2Reproducibility—Tworesults,eachthemeanofdu-plicatesortriplicates,obtainedbydifferentoperatorsshouldbeconsideredsuspectiftheydifferbymorethantworatingunits.14.2Biascannotbeestablishedforthesetestmethods.15.Keywords

15.1adhesion;crosscutadhesiontestmethod;tape;tapeadhesiontestmethod;X-cutadhesiontestmethod

APPENDIX

(NonmandatoryInformation)X1.COMMENTARY

X1.1Introduction

X1.1.1Giventhecomplexitiesoftheadhesionprocess,canadhesionbemeasured?AsMittal(1)12haspointedout,theanswerisbothyesandno.Itisreasonabletostatethatatthepresenttimenotestexiststhatcanpreciselyassesstheactualphysicalstrengthofanadhesivebond.Butitcanalsobesaidthatitispossibletoobtainanindicationofrelativeadhesionperformance.

X1.1.2Practicaladhesiontestmethodsaregenerallyoftwotypes:“implied”and“direct.”“Implied”testsincludeinden-tationorscribetechniques,rubtesting,andweartesting.Criticismofthesetestsariseswhentheyareusedtoquantifythestrengthofadhesivebonding.Butthis,infact,isnottheirpurpose.An“implied”testshouldbeusedtoassesscoatingperformanceunderactualserviceconditions.“Direct”mea-surements,ontheotherhand,areintendedexpresslytomeasureadhesion.Meaningfultestsofthistypearehighlysoughtafter,primarilybecausetheresultsareexpressedbyasinglediscretequantity,theforcerequiredtorupturethecoating/substratebondunderprescribedconditions.DirecttestsincludetheHesiometerandtheAdherometer(2).Com-monmethodswhichapproachthedirecttestsarepeel,lap-shear,andtensiletests.

X1.2TestMethods

X1.2.1Inpractice,numeroustypesoftestshavebeenusedtoattempttoevaluateadhesionbyinducingbondrupturebydifferentmodes.Criteriadeemedessentialforatesttowarrantlarge-scaleacceptanceare:useofastraightforwardandunam-biguousprocedure;relevancetoitsintendedapplication;re-peatabilityandreproducibility;andquantifiability,includingameaningfulratingscaleforassessingperformance.

X1.2.2Testmethodsusedforcoatingsonmetalsare:peeladhesionor“tapetesting;”Gardnerimpactflexibilitytesting;andadhesivejointtestingincludingshear(lapjoint)anddirecttensile(buttjoint)testing.Thesetestsdonotstrictlymeetallthecriterialisted,butanappealingaspectofthesetestsisthatinmostcasestheequipment/instrumentationisreadilyavail-ableorcanbeobtainedatreasonablecost.

X1.2.3Awidediversityoftestsmethodshavebeendevel-opedovertheyearsthatmeasureaspectsofadhesion(1-5).Theregenerallyisdifficulty,however,inrelatingtheseteststobasicadhesionphenomena.

X1.3TheTapeTest

X1.3.1Byfarthemostprevalenttestforevaluatingcoating“adhesion”isthetape-and-peeltest,whichhasbeenusedsincethe1930’s.Initssimplestversionapieceofadhesivetapeispressedagainstthepaintfilmandtheresistancetoanddegree

12Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendofthistestmethod.

offilmremovalobservedwhenthetapeispulledoff.Sinceanintactfilmwithappreciableadhesionisfrequentlynotremovedatall,theseverityofthetestisusuallyenhancedbycuttingintothefilmafigureXoracrosshatchedpattern,beforeapplyingandremovingthetape.Adhesionisthenratedbycomparingfilmremovedagainstanestablishedratingscale.Ifanintactfilmispeeledcleanlybythetape,orifitdebondsjustbycuttingintoitwithoutapplyingtape,thentheadhesionisratedsimplyaspoororverypoor,amorepreciseevaluationofsuchfilmsnotbeingwithinthecapabilityofthistest.

X1.3.2Thecurrentwidely-usedversionwasfirstpublishedin1974;twotestmethodsarecoveredinthisstandard.Bothtestmethodsareusedtoestablishwhethertheadhesionofacoatingtoasubstrateisatanadequatelevel;howevertheydonotdistinguishbetweenhigherlevelsofadhesionforwhichmoresophisticatedmethodsofmeasurementarerequired.Majorlimitationsofthetapetestareitslowsensitivity,applicabilityonlytocoatingsofrelativelylowbondstrengths,andnon-determinationofadhesiontothesubstratewherefailureoccurswithinasinglecoat,aswhentestingprimersalone,orwithinorbetweencoatsinmulticoatsystems.Formulticoatsystemswhereadhesionfailuremayoccurbetweenorwithincoats,theadhesionofthecoatingsystemtothesubstrateisnotdetermined.

X1.3.3Repeatabilitywithinoneratingunitisgenerallyobservedforcoatingsonmetalsforbothmethods,withreproducibilityofonetotwounits.Thetapetestenjoyswidespreadpopularityandisviewedas“simple”aswellaslowincost.Appliedtometals,itiseconomicaltoperform,lendsitselftojobsiteapplication,andmostimportantly,afterdecadesofuse,peoplefeelcomfortablewithit.

X1.3.4Whenaflexibleadhesivetapeisappliedtoacoatedrigidsubstratesurfaceandthenremoved,theremovalprocesshasbeendescribedintermsofthe“peelphenomenon,”asillustratedinFig.X1.1.

X1.3.5Peelingbeginsatthe“toothed”leadingedge(attheright)andproceedsalongthecoatingadhesive/interfaceorthecoating/substrateinterface,dependingontherelativebondstrengths.Itisassumedthatcoatingremovaloccurswhenthetensileforcegeneratedalongthelatterinterface,whichisafunctionoftherheologicalpropertiesofthebackingandadhesivelayermaterials,isgreaterthanthebondstrengthatthecoating-substrateinterface(orcohesivestrengthofthecoat-ing).Inactuality,however,thisforceisdistributedoveradiscretedistance(O-A)inFig.X1.1,whichrelatesdirectlytothepropertiesdescribed,notconcentratedatapoint(O)inFig.X1.1asinthetheoreticalcase—thoughthetensileforceisgreatestattheoriginforboth.Asignificantcompressiveforcearisesfromtheresponseofthetapebackingmaterialtobeingstretched.Thusbothtensileandcompressiveforcesarein-volvedinadhesiontapetesting.

X1.3.6Closescrutinyofthetapetestwithrespecttothe

FIG.X1.1PeelProfile(6)

natureofthetapeemployedandcertainaspectsoftheprocedureitselfrevealseveralfactors,eachoranycombinationofwhichcandramaticallyaffecttheresultsofthetestasdiscussed(6).

X1.4PeelAdhesionTestingonPlasticSubstrates

X1.4.1Tapetestshavebeencriticizedwhenusedforsubstratesotherthanmetal,suchasplastics.Thecentralissuesarethatthetestonplasticslacksreproducibilityanddoesnotrelatetotheintendedapplication.Bothconcernsarewellfounded:poorprecisionisadirectresultofseveralfactorsintrinsictothematerialsemployedandtheprocedureitself.Moreimportantly,inthisinstancethetestisbeingappliedbeyonditsintendedscope.Thesetestmethodsweredesignedforrelativelyductilecoatingsappliedtometalsubstrates,notforcoatings(oftenbrittle)appliedtoplasticparts(7).Theuniquefunctionalrequirementsofcoatingsonplasticsub-stratescausetheusualtapeteststobeunsatisfactoryformeasuringadhesionperformanceinpractice.

X1.5TheTapeControversy

X1.5.1Withthewithdrawalfromcommerceofthetapespecifiedoriginally,3MNo.710,currenttestmethodsnolongeridentifyaspecifictape.Differencesintapesusedcanleadtodifferentresultsassmallchangesinbackingstiffnessandadhesiverheologycauselargechangesinthetensionarea.Somecommercialtapesaremanufacturedtomeetminimumstandards.Agivenlotmaysurpassthesestandardsandthusbesuitableforgeneralmarketdistribution;however,suchalotmaybeasourceofseriousandunexpectederrorinassessingadhesion.Onecommerciallyavailabletapetestkithadin-cludedatapewithadhesionstrengthvariationsofupto50%claimedbythemanufacturer.Also,becausetapeschangeonstorage,bondstrengthsofthetapemaychangeovertime(7,8).X1.5.2Whiletherearetapesavailablethatappeartodeliverconsistentperformance,agiventapedoesnotadhereequallywelltoallcoatings.Forexample,whenthepeelremovalforceofthetape(fromthecoating)usedearlierbyTaskGroupD01.23.10toestablishprecisionofthemethod,by3MNo.710wasexaminedwithsevendifferentelectromagnetic

interference/radiofrequencyinterference(EMI/RFI)coatings,itwasfoundthat,whilepeelwasindeedconsistentforagivencoating,thevaluevariedby25%betweenthehighestandlowestratingsamongcoatings.Severalfactorsthatcontributetothesedifferencesincludecoatingcompositionandtopology:asaresult,nosingletapeislikelytobesuitablefortestingallcoatings.Further,thetapetestdoesnotgiveanabsolutevaluefortheforcerequiredforbondrupture,butservesonlyasanindicatorthatsomeminimumvalueforbondstrengthwasmetorexceeded(7,8).

X1.6ProceduralProblems

X1.6.1Thetapetestisoperatorintensive.Bydesignitwasmadeassimpleaspossibletoperform,andrequiresamini-mumofspecializedequipmentandmaterialsthatmustmeetcertainspecifications.Theaccuracyandprecisiondependlargelyupontheskilloftheoperatorandtheoperator’sabilitytoperformthetestinaconsistentmanner.Keystepsthatdirectlyreflecttheimportanceofoperatorskillincludetheangleandrateoftaperemovalandthevisualassessmentofthetestedsample.Itisnotunexpectedthatdifferentoperatorsmightobtaindifferentresults(7,8).X1.6.2PeelAngleandRate:

Thestandardrequiresthatthefreeendofthetapeberemovedrapidlyatasclosetoa180°angleaspossible.Ifthepeelangleandratevary,theforcerequiredtoremovethetapecanchangedramatically.Nearlylinearincreaseswereobservedinpeelforceapproaching100%aspeelanglewaschangedfrom135to180,andsimilarlargedifferencescanbeexpectedinpeelforceaspeelratevaries.Theseeffectsarerelatedastheyreflectcertainrheologicalpropertiesofthebackingandadhesivethataremolecularinorigin.Variationinpullrateandpeelanglecaneffectlargedifferencesintestvaluesandmustbeminimizedtoassurereproducibility(9).X1.6.3VisualAssessment:

Thefinalstepinthetestisvisualassessmentofthecoatingremovedfromthespecimen,whichissubjectiveinnature,sothatthecoatingscanvaryamongindividualsevaluatingthesamespecimen(9).

X1.6.3.1Performanceinthetapetestisbasedontheamountofcoatingremovedcomparedtoadescriptivescale.Theexposureofthesubstratecanbeduetofactorsotherthancoatingadhesion,includingthatarisingfromtherequirementthatthecoatingbecut(hencethesynonym“cross-hatchadhesiontest”).Justificationforthecuttingstepisreasonableascuttingprovidesafreeedgefromwhichpeelingcanbeginwithouthavingtoovercomethecohesivestrengthofthecoatinglayer.

X1.6.3.2Cuttingmightbesuitableforcoatingsappliedtometalsubstrates,butforcoatingsappliedtoplasticsorwood,theprocesscanleadtoamisleadingindicationofpooradhesionduetotheuniqueinterfacialzone.Forcoatingsonsoftsubstrates,issuesincludehowdeepshouldthiscutpenetrate,andisitpossibletocutonlytotheinterface?

X1.6.3.3Ingeneral,ifadhesiontestpanelsareexaminedmicroscopically,itisoftenclearlyevidentthatthecoatingremovalresultsfromsubstratefailureatorbelowtheinterface,andnotfromtheadhesivefailurebetweenthecoatingandthesubstrate.Cohesivefailurewithinthecoatingfilmisalso

frequentlyobserved.However,withthetapetest,failureswithinthesubstrateorcoatinglayersarerarebecausethetapeadhesiveisnotusuallystrongenoughtoexceedthecohesivestrengthsofnormalsubstratesandorganiccoatings.Althoughsomeratherbrittlecoatingsmayexhibitcohesivefailure,thetapetestadhesionmethoddoesnotmakeprovisionforgivingfailurelocality(7,8).

X1.6.4Useofthetestmethodinthefieldcanleadto

variationintestresultsduetotemperatureandhumiditychangesandtheireffectupontape,coatingandsubstrate.X1.7Conclusion

X1.7.1Alltheissuesaside,ifthesetestmethodsareusedwithintheScopeSectionandareperformedcarefully,someinsightintotheapproximate,relativelevelofadhesioncanbegained.

REFERENCES

(1)Mittal,K.L.,“AdhesionMeasurement:RecentProgress,UnsolvedProblems,andProspects”,“AdhesionMeasurementofThinFilms,ThickFilms,andBulkCoatings,”ASTMSTP0,ASTM,1978,pp.7–8.

(2)Corcoron,E.M.,“Adhesion,”Chapter5.3,PaintTestingManual,13thed.,ASTMSTP500,ASTM,1972,pp.314–332.

(3)Gardner,H.A.,andSward,G.G.,PaintTestingManual,12thed.,Chapter7,GardnerLaboratory,Bethesda,MD,1962,pp.159–170.(4)Mittal,K.L.,JournalofAdhesionScienceandTechnology,Vol1,No.3,1987,pp.247–259.

(5)Stoffer,J.O.,andGadodia,S.K.,AmericanPaintandCoatings

Journal,Vol70,Nos.50and51,1991,pp.36–40and36–51,respectively.

(6)Souheng,Wu,PolymerInterfaceandAdhesion,MarcelDekker,Inc.,NewYork,NY,1982,p.531.

(7)Nelson,G.L.,Gray,K.N.,andBuckley,S.E.,ModernPaintandCoatings,Vol75,No.10,1985,pp.160–172.

(8)Nelson,G.L.,andGray,K.N.,“CoatingAdhesiontoPlastics,”Proceedings,WaterborneandHigherSolidsCoatingsSymposium,Vol13,NewOrleans,LA,February5–7,1986,pp.114–131.

(9)K.L.Mittal,ed.,“SymposiumonAdhesionAspectsofPolymericCoatings,”Proceedings,TheElectrochemicalSociety,1981,pp.569–582.

SUMMARYOFCHANGES

CommitteeD01hasidentifiedthelocationofselectedchangestothisstandardsincethelastissue(D3359-97)thatmayimpacttheuseofthisstandard.

(1)DeletedreferencetoTestMethodD2197inReferencedDocumentssectionandeditoriallychangedfootnote10toavoidconfusionwithanotheradhesiontestmethod.

(2)Added7.1.1,8.5,12.1.1,and13.4toclarifyusewhentestingsamplesthathavebeenimmersed.

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