Dow Corning® Silicone Reactive Hot-Melt Adhesive Window Assembly Sealants

Technical Manual

Table of ContentsIntroduction

Product Information

Quality Assurance

IndustryCertifications

SubstrateSelection

Adhesion

MaterialCompatibility

ShelfLifeandStorageConditions

Sealant Design Considerations

CureRequirements

DeterminingandMaintainingSealant JointDimensions

Glue-LineThicknessandJoint MovementCalculations

DeterminingThermally-induced DifferentialMovement

DeterminingSealantGlue-LineThickness

BiteCalculationforWindLoad

BiteCalculationforDeadLoad

SettingBlocks

TypicalYield

Application

SafeHandlingInstructions

VolatileOrganicContent(VOC)

ProductHandlingPrecautions

SafetyInstructions

RecommendedPersonal ProtectiveEquipment

QualityControl

DeterminationofCureState

SubstratePreparation

In-ShopApplication

DispensingEquipment

2

2

2

2

3

3

3

3

4

4

5

5

6

7

7

8

8

8

8

8

9

9

9

9

9

9

10

10

10

1

GlazingTable

ManufacturingProcessConditions

DispensingTemperatures

DispensingTooHot

DispensingTooCold

GlazingProcess

GeneralConsiderationsforApplying Dow Corning®InstantGlazeWindow AssemblySealants

ShutDownConsiderations

QualityControlandApplicationIssues

BeadLocation

BeadConsistencyandUniformity

SubstrateIssues:UnevenSurfaces inWindowSash

EquipmentIssues

EnvironmentalIssues

Deglazing and Reglazing of Window Units

ShopReglazing

FieldReglazing

Finished Unit Recommendations

Comparative Performance

GreenStrength

Adhesion-in-peelStrength

10

10

11

12

12

12

12

13

13

13

13

14

14

14

15

15

15

15

16

16

16

2

IntroductionThismanual is intended to provide technical information,selectionandapplicationguidelinesfortheDow Corning® brandofpatented,neutral-cure,reactivehot-meltadhesives.Thesehot-meltadhesiveproductsaredesignedforautomat-ed back-bedding application in the assemblyofwindowsand doors, and become part of a total manufacturingproductivity solution when used with standard hot-meltdispensingequipmentandanautomatedX–Yglazingtable.

Thismanualcannotbeconsideredacomprehensiveguide asfenestrationproductsvaryinmanyaspects,includingde-sign,customerrequirements,manufacturingenvironmentsandend-useapplications.Forthepurposeofthismanual,anyreferencetowindowscanbeconsideredinterchangeablewithdoors.

DowCorningTechnicalCustomerServiceprovidesprocess workflowsandresourcestomanageproductandtechnicalinformationinquiriesfromcustomers.Theseinquiriesmayincludebutarenotlimitedto:

• Productrecommendations• Producttroubleshooting• Applicationassistance• Environmental,health,safetyandsustainabilitydata

Inquiriesarereceivedviae-mailortelephone:

• E-mail:construction@dowcorning.com• Telephone:+18002482481

Product InformationDowCorningcurrentlyoffers threemoisture-reactivehot-meltproductsasawindowassemblysealant/adhesivetomeetcustomer-specificapplicationneeds.Theseproductscanbeusedindifferentapplicationsinthewindowindustrythatrequirebondingandsealing.

• DowCorning® InstantGlaze Window Assembly Seal-ant: Thissealantisdesignedforuseasaback-beddingsealant onmost commonwindowmaterials for stan-dard and impact-resistant glazing, and is compatiblewithcommoninsulatingglasssealants.Dow Corning® InstantGlazeSealantdispensesintoacrystalclearseal-antbeadorcanbecustompigmentedforlargevolumeapplications. It provides instant green strength, a15-minuteopentime,primerlessadhesionand±50%movementcapability.

• Dow Corning® InstantGlaze II Window Assembly Sealant: This sealant is offered as a lower viscosityand lower durometer alternative to Dow Corning® InstantGlaze Sealant for use by customers where these

features are desirable.Dow Corning® InstantGlaze II Sealantdispensesintoacrystalclearsealantbeadorcanbecustompigmentedforlargevolumeapplications.Itprovidesinstantgreenstrength,a15-minuteopentime,primerlessadhesionand±50%movementcapability.

• Dow Corning® InstantGlaze III Window Assembly Adhesive: This sealant is designed for use wherebetter resistance to creep, due to higher static loadsin the window design, is desirable.Dow Corning® InstantGlaze III Adhesive dispenses into a translucent sealant bead or can be custom pigmented for large volume applications. It provides instant green strength, a 15-minute open time, primerless adhesion and±50% movementcapability.

Formore information, visit dowcorning.com/construction orwww.instantglaze.comfor(Material)SafetyDataSheets,productdata sheetsandadditional informationonall Dow Corning®siliconereactivehot-meltadhesivewindowassemblysealants.

Quality AssuranceDowCorningconductsqualityassurancetestinginitsseal- antmanufacturingfacilities thatarecertifiedinaccordancetoISO9001andResponsibleCare®RC14001requirements.

Industry CertificationsEach product is approved as a bonding, back-bedding sealant compound by theAmericanArchitecturalManu-facturersAssociation (AAMA) andmay be found on the AAMAVerifiedComponentsList.ThemostrecentversionofthislistmaybefoundontheAAMAwebsite:

www.aamanet.org/general/1/111/verified-components.

Verified components on this list are tested perAAMA 800-10, Voluntary Specifications and Test Methods for Sealants, Section 1.1, Back-Bedding Glazing Compounds.

As of the publication date of thismanual, these productsareverifiedasback-beddingglazingcompoundsforcertifiedwindowsanddoors:

• AAMA805.2-10,GroupC:Dow Corning® InstantGlaze Sealant and Dow Corning® InstantGlaze II Sealant

• AAMA805.2-10,GroupA:Dow Corning® InstantGlaze IIIAdhesive

TheAAMA805.2classification is forapumpableandgunnablecompoundused tobedglass to the surroundingsubstrateandisintendedtobondtheglasstothesubstrateandpreventairinfiltrationandwaterpenetration.The805.2 compoundscurerelativelyhardandstiffandpermitlimited movementwithoutlossofbond.Theperformancerequire-mentsforthe805.2classificationinclude:

3

• Hardness:When tested in accordance toASTMC661, theShoreAhardnessshallnotexceed70durometer.

• Thin Film Integrity:Thereshallbenopresenceofvoidswithinthe805.2compoundwhentestedinaccordancetoAAMA800-10,Section2.3.

• Peel Strength:Whenlaboratorytestedforpeeladhesion (modifiedASTMC794),805.2compoundsshallexhibitpeelstrengthsofatleast12.5pli(lbfperinchofwidth).

• Failure Mode:When laboratory testedforpeeladhe- sion(modifiedASTMC794)or,alternatively,lapshear(modifiedASTMC961),GroupCshalldemonstratepredominantlycohesivefailure(>90%).GroupAislimitedtochemicallycuringsealantswhichdemonstrateadhesivefailurebutwhichhavebeenshowntoprovideacceptablefieldperformance.

• Vehicle Migration:Thereisnovehiclemigrationfroman 805.2compoundedgewhentested inaccordancewith amodifiedASTMD2203(AAMA800-10,Section2.8.1).

• Low Temperature Flexibility: 805.2 compoundsshallhavenocracksand/orlossofadhesionfromthetestpanelwhentestedinaccordancewithamodifiedASTMC734(AAMA800-10,Section2.9.1).

• Water Resistance:805.2compoundsshalldemonstrate nopresenceofvoids,cracks,separationorbreakdown whentestedinaccordancetoAAMA800-10,Section2.11.1.

Substrate SelectionDow Corning® InstantGlazeWindowAssemblyproductsaresuitableforback-beddingapplicationsutilizing,butnotlimitedto,thefollowingsubstrates:

• Aluminum◦ Anodized◦ Millfinished◦ Kynar®(polyvinylidenefluoride)finish◦ Duranar®finish

• Fiberglassandothercompositematerials• Glass• PolyvinylChloride• Wood◦ Clad◦ Primedorunprimed◦ Treated

AdhesionAll Dow Corning®windowassemblysealantsaredesignedtoexhibitexcellentadhesiontocommonsubstratesovera widetemperaturerangeanddonotrequiresurfacepriming. Substratesmaybesubjecttofurthertreatmentandcoating toenhancedurability.Allsubstratesshouldbetestedaspart of the sealant selection process. Consult a DowCorning

ApplicationEngineerwhensubstrateschangeornon-typical finishesarespecified.

TheDowCorning test laboratory located inMidland,Michiganoffersavarietyofcapabilitiestoensurethata particularsealantwillmeetacustomer’sdesignrequirementsforthewindowapplication.TheadhesionofDowCorningproductstoacustomer-specificsubstrateisevaluatedusingamodifiedversionofASTMC794Standard Test Method for Adhesion-in-Peel of Elastomeric Joint Sealants.

Material CompatibilityTheDowCorningtestlaboratoryconductscompatibilitytestingaccordingtoASTMC1087Standard Test Method for Determining Compatibility of Liquid-Applied Sealants with Accessories Used in Structural Glazing Systems.Inaddition tothesuitabilityofsubstratesforadhesion,componentssuchassettingblocks,weatherstripping,gasketsandother windowaccessorymaterialsmustbecompatiblewith Dow Corning®sealants.Chemicalincompatibilitiesbetween materialsmayresultindiscoloration,lossofadhesion and/orinhibitthecureofthesiliconesealant.

Basedonhistoricaltesting,somecommonmaterials,suchas siliconeweatherseals,siliconeinsulatingglasssealants,polyurethanefoamtapeandvinylextrusions,arefoundto becompatiblewithDow Corning®InstantGlazeWindow Assemblyproductswithnodiscolorationorcureinhibition.

Othermaterials,suchasethylenepropylenedienemonomer (EPDM)rubber,neoprene,Santoprene®,Kraton®andother similarorganicmaterialsaretypicallyfoundtocauseslight discolorationoflight-coloredsealants.Thesematerialsare usuallyapprovedforincidentalcontactwithglazing-typesiliconesofallcolors;butpigmentedsealantsmaybepreferableifthesealantlineisvisibleorifanypotentialdiscolorationneedstobemasked.

ContactaDowCorningApplicationEngineerforquestionsregardingcompatibilityandtesting.Standardtestsrequirefourweeksfromreceiptoftestsamples.DowCorningcanaccommodatenon-standardtestswithsufficientleadtimes,whichmaybesubject toaservicefee.Testreportsfrom DowCorningshouldnotbeinterpretedasapprovals.

Shelf Life and Storage ConditionsItisimportanttouseanyDowCorningproductwithinitsrecommendedshelflife.Theexpirationdate(EXPDATE)isclearlydisplayedonthepackaginglabel.Dow Corning®

InstantGlazeWindowAssemblyproductsshouldbestoredintheiroriginal,unopenedcontainersinacleananddryenvironment below 90°F (32°C). These products have a shelflifeof12monthsfromthedateofmanufacturewhen storedbelow90°F,andarepackagedinair-tightcontainersbecauseofitsreactivitytoatmosphericmoisture.

0.6

Cur

e-in

-dep

th, c

m

0.5

0.4

0.3

0.2

0.1

0.00 6 12 18 24 30 36 42 48

Elapsed time after glazing window, hours

7/32

3/16

Cur

e-in

-dep

th, i

n

5/32

1/8

3/32

1/16

1/32

0.00 6 12 18 24 30 36 42 48

Elapsed time after glazing window, hours

Figure 1:Typicalcure-in-depthratesforDow Corning® InstantGlaze WindowAssemblyproductsatthreedifferentsetsoftemperaturesandrelativehumidities

32°C, 60% RH

25°C, 50% RH

16°C, 30% RH

90°F, 60% RH

77°F, 50% RH

60°F, 30% RH

4

Sealant Design ConsiderationsProperly installed and fully cured back-bedding sealantallowthewindowunittoholduptoawiderangeofweatheconditions and pass design pressure testing.The sealanserves a primary purpose as aweatherseal to prevent ainfiltrationandwaterpenetration.Thesealant isdesignetoadhereandabsorbstressesbetweenthewindowsashantheglassasaconsequenceofmovement fromthermallinduced expansion or contraction and wind loads. Thmovementcapabilityofafully-curedsealanthelpsabsorthese stresses, rather than distribute them throughout thwindowunittoothercomponents,suchastheglass.

Theglue-linethicknessofacuredsealantmustbedesignetoaccommodatejointmovementsduetodifferencesinththermalexpansionofthedifferentmaterialsinthewindowunit.Thejointbite—theminimumwidthorcontactsurfacofthesealantonboththewindowsashandglass—musbedesignedtoaccommodatebothdeadloadsanddynamiloadssuchasfromthermalfluctuations,windorimpacInallcases,opposite-sidemechanicalsupportssuchasglazinbeadsarerequiredastheproductsinthismanualarenoconsideredstructuralsealantsasdefinedbyASTMC118Standard Specification for Structural Silicone Sealants.

Cure RequirementsAll Dow Corning®one-partwindowsealantscurebyre-actingwithmoistureintheatmosphere.Therateofcuredependsonthediffusionofatmosphericmoisturethroughtheinterfaceoftheexposedsealantwithinthesealantjoint.Therefore,one-partsealantscurefromtheoutsidesurfaceinward.Therateofmoisturediffusionisaffectedbyseveralfactorsincluding:

• Partial pressure of water vapor: This depends ontemperatureandhumidityintheimmediatesurroundings,and is thedrivingforce fordiffusion. Increasing tem-peraturewithout changing thewater content in theatmosphere(suchthat therelativehumiditydecreases)willnotacceleratecure.

• Dimensions of the sealant joint: The diffusion rateof moisture obeys Fick’s law and is proportional to the square root of time. Therefore, the length of time needed for the one-part sealant to fully cure increases significantlywithanincreasinglydeepersealantjoint.

• Joint configuration or joint design: Areas such as corner keys and windows with tight clearances maynotaffordone-partsealantswithsufficientexposuretoatmosphericmoisture,andtightclearanceswithlittleaccess to theatmospherewillslowthecureprocess.Conversely, porous substrates will interfere less withthe cure process and small amounts of absorbedmoisture(suchaswithwoodsubstrates)mayacceleratethecureprocess.

• Sealant composition: Silicones are more permeablethan organic materials. To improve mechanical strength,

s silicone sealants are formulated with inorganic fillers,r which decrease the moisture diffusion rate. Thist decrease will depend on the type and the amount ofir fillerinthesealant.d

Figure1providesunidirectionalcure-in-depthprofilesfordthreedifferentsetsofconditionsoverthefirst48hoursyafterapplicationthatmaybeexpectedfromDow Corning® eInstantGlazeWindowAssemblyproducts.Theactualcurebperformancemayvarydependingonjointdesign.eAll Dow Corning®InstantGlazeWindowAssemblyproducts provideinstantgreenstrength.Greenstrengthcanbede-dscribedastheinitialshearstrengthbeforethesealantstartseto exhibit sufficient cure that, in turn, buildsmechanicalandadhesionstrength.Thegreenstrengthofthesehot-melteproductswill reduce hold times in thewindow assemblytprocessnecessaryforsufficientcuretooccur.UnitsmadecwithDow Corning®InstantGlazeWindowAssemblyprod-t. ucts have been successfully tested for air infiltration andg waterpenetrationwithinhoursofmanufactureaccordingtotASTME283Standard Test Method for Determining Rate 4 of Air Leakage through Exterior Windows, Curtain Walls, and Doors Under Specified Pressure Differences Across the

5

SpecimenandASTME331Standard Test Method for Water Penetration of Exterior Windows, Skylights, Doors, and Curtain Walls by Uniform Static Air Pressure Difference.

Whilesealantgreenstrengthdoesallowforimprovedman-ufacturingthroughput,careshouldstillbetakentoensurewindowunitsarenotallowedtorackduringthepackagingorshippingprocess.Ifthesealantisnotfullycured,unitsthatbecomeout-of-squarecansetintothisdistortedshapeduetotherackingforcesovercomingthegreenstrengthofthematerial.

Determining and Maintaining Sealant Joint DimensionsNote: It is the responsibility of the window manufacturer to determine the appropriate bead size that will deliver the necessary joint dimensions for each product design, joint configuration and application based on the sealant properties provided in the product data sheet. It is incum-bent on the window manufacturers to rely on their experience and to validate product design by performing the necessary unitized industry tests.Glue-line thickness is defined as the sealant thickness necessary to absorbmovement expected between thewindowsashandtheglassduetoclimatic-inducedloads.Todetermineglue-linethickness,thefirststepistoidentifythedirectionandmagnitudeofthemovement.Thesealantgenerallyundergoesthemostmovementinthedirectionofthelongestdimensionofthewindow.

Asabasisfordeterminingtheappropriateglue-linethicknesswhenusingDow Corning®InstantGlazeWindowAssembly products,itisrecommendedtostartwitha3/16-inch(5mm) nominalbeaddiameter.Theinitialbeaddiameterwillcon-tractinvolumebyapproximately6%asitcoolsdownfrom itsrecommendeddispensingtemperature.Thisbeaddiam-eter, assuming no squeeze out, results in a typical bite(contactwidth)ofapproximately1/2inch(13mm),andacompressed sealant glue-line thickness of approximately0.055 inch (1.3mm).WhileDow Corning® InstantGlaze Window Assembly products may in some applicationsexhibit sufficient stiffness between the window sash andtheinsulatingglass(IG)unit,thisbehaviorcannotbesolelyreliedupontomaintainglue-linethickness.Bumpers,suchas thoseused in aluminumapplications, and/orglazinglegs,suchasthoseseeninvinylandwoodapplications,arerequiredtomaintaintheappropriateglue-linethicknessandtominimize excessive squeeze out.DowCorning recom-mends glue-line thickness requirements be assessed byconductingmovementcapabilitytestsand/orfiniteelementanalysisforeachwindowdesign.

Attentionshouldnextbegiventotheapplicationprocesstoverifythatasufficient,uniformandconsistentbeadisappliedaroundtheentireperimeteroftheglazinglegwith

noskips,thinspotsorshallowareas.Iftheapplicationequipmentisnotrobustenoughtoensureaconsistentlyappliedminimumglue-lineprofile(biteandthickness)accordingtodesigncalculations,asafetyfactorshouldbe appliedtoincreasetheoverallbeadsizesothatthedesign requirementsaremetinworst-casesituationsorlocations.

Care should also be taken in the dispensing process toensuretheglue-linethicknessdoesnotfallbelowthedesignrequirement.Excessivesealantcompressionafterbeddingthe glass and installing opposite-side glazing beads mayreduce theglue-line thickness such that severe climatic-induced movements may exceed the sealant’s movementcapability.Wood, vinyl andfiberglass sashprofiles typical-lyhaveglazingdamstoestablishandmaintainthedesignglue-line thickness. It is unacceptable for glass tomakecontactwithaluminumsashprofiles such that tapesandbumpersareoccasionallyusedtoensureandmaintaintheappropriateglue-line thickness.Regardlessof themethodtomaintainglue-linethickness,themaintakeawayshouldbethatadefinablethicknessisrequiredtoallowthesealanttoperformitsdesignedfunctions.

Glue-Line Thickness and Joint Movement CalculationsAproperlydesignedglue-linethicknesswillfacilitatethe assemblyprocessofwindowunitsandminimizestresses onthesealantjointandinterfacesresultingfrommovements duetothermalexpansionandwindloads.Glazedwindowsundergoexpansionandcontractionmovementsduetodiurnal temperaturecycles,heattraps,windloadsandproximitytoheatingandairconditioningvents.Theglue-lineshouldbedesignedtoaccommodatethesemovementsinordertominimizestressandpreventtheglassfrombreaking.

Thermally-induced movement may be estimated for any window sash profile or IG unit if its length (longest di- mension),compositionandlinearcoefficientofthermalexpansion(CTE)areknown.LinearCTEvaluesfortypicalwindowsashmaterialsintheproximityof77°F(25°C)arelistedinTable1.

Table 1: Linear coefficient of thermal expansion for typicalwindowsashmaterials

MaterialLinear Thermal Expansion Coefficients

10–6 in/in∙°F 10–6 m/m∙K

Aluminum 12.3 – 13.2 22.2 – 23.8

Fiberglass 6.5 11.7

Float Glass 5.0 – 5.1 9.0 – 9.2

PVC 28 50.4

Wood 2.1 – 3.0 3.8 – 5.4

6

Themaximumthermalmovement(expansionorcontraction) foraparticularmaterialfromachangeintemperatureΔT canbecalculatedasfollows:

Movement(in)=Length(in)×CTE(in/in∙°F)×ΔT(°F)

Figure2 compares themovement, either contractionor expansion, for every10 lineal inchesof typicalwindowmaterials resulting from a 10°F (5.6°C) change in tem-peratureusingtheaveragelinearCTEdatafromTable1.

Determining Thermally-induced Differential MovementGlazedwindowsundergoexpansionandcontractionmove-mentsduetodiurnal temperaturecycles,heat trapsandproximitytoheatingandairconditioningvents.Theglue-lineshouldbedesigned toaccommodate thesemovementstominimizestressandprevent theglass frombreaking.Thermally-induceddifferentialmovementmaybeestimatedforanywindowsashprofileandIGunitifitslength(longestdimension),compositionandCTEareknown.CTEvaluesfortypicalwindowsashmaterialcompositionsintheprox- imityof77°F(25°C)arelistedinTable1.BecauseIGunitsarealmostalwayssupportedonthebottombysettingblocks, andbecauseaspect ratios are such thatwindowsare typi-cally taller than they are wide, the largest magnitude ofthermalmovementistypicallyintheverticaldirection.Thethermally-inducedmovement in the vertical directionδv maybeestimatedbythefollowingformulawhereh is the heightofthewindowunit;CTEsashandCTEglass the linear CTEof thewindowsashandglass lite, respectively;andΔTsashandΔTglassthedifferentialtemperatureofthewindowsashandglasslite,respectively,relativetowhenthewindowunitwasassembledduringthemanufacturingprocess.

δv=h ∙(CTEsash ∙ΔTsash–CTEglass∙ΔTglass)

Assumingawindowisfreetoexpandandcontractinbothhorizontaldirectionsfromitscenterline, thermally inducedmovementδwexperiencedbythesealantacrossthewidth fromthecenterlineofthewindowmaybeestimatedbythe followingformulawherewisthewidthofthewindowunit.

δw=(w/2)∙(CTEsash ∙ΔTsash–CTEglass∙ΔTglass)

Indetermining thermally-inducedmovement inawindowunit,thedesignerseekstheresultwiththehighermagnitudeforthepurposeofcalculatingtheglue-linethickness.Unlessthewidthofthewindowunitismorethantwiceitsheight,inalmostallcasesthemovementintheverticaldirectionisgoingtobethevalueofhighermagnitude.

Sample Calculations

Awindowmanufacturerisassemblingaseriesofwindowsintended foruse inanenvironmentwhere theexpectedmaximumandminimumtemperaturesare140°F(60°C)and–15°F (–26°C), respectively. The factory where the unitsaremanufacturedismaintainedat65°F(18°C).Therefore,the temperature differential is greatest during the coldcondition,(65°F–(–15°F)=80°F).BecausetheIGunithasinsulatingcapability, it isexpectedtobewarmer thanthewindowsash.Figure3shows the resultingmovement fordifferentwindowheightswhenΔTglass isvariedfrom40°Fto80°F.Thetemperatureofthewindowsash,eitherPVC(topgraph)oraluminum(bottomgraph),isassumedtobe10°F(5.6°C)cooler.

0.0

0.00

0.00

9

9

8

8

7

7

6

6

80

80

5

5

70

70

4

4

60

60

3

3

50

50

2

2

40

40

Aluminum

1 mil = 0.001 in

PVC – Glass

Aluminum – Glass

ΔT glass, °F

ΔT glass, °F

Window height h, ft

Window height h, ft

Fiberglass Float Glass

PVC Wood

0.5

0.05

0.01

1.0

0.10

0.02

1.5

0.15

0.03

0.04

0.05

2.02.53.0

0.20

0.06

Mov

emen

t, m

il

Ther

mal

mov

emen

t, in

Ther

mal

mov

emen

t, in

Figure 2:Movementforevery10linealinchesoftypicalwindow materialsduetoa10°F(5.6°C)changeintemperature

Figure 3:Thermally-inducedmovementasafunctionofwindowheightandΔTglasswhereΔTsashisassumedtobe10°Fcooler

Sample CalculationsJointmovement:

• Fora3ft×5ftglasslitefixedatthesillandatemper- aturechangeof40°Foverthecourseofa24-hourday,theglass(CTE~5.1×10–6/°F)willexhibitamaximum jointmovementbof:5ft∙(12in/ft)∙5.1×10–6in/in∙°F∙40°F=0.012in

• Avinylsashprofile(CTE~28×10–6/°F)willexpandby 0.067infromanincreaseof40°F

• Differentialmovementbis0.067–0.012=0.055inSealantmovement:

• Foradifferentialmovementb=0.055in,aback-bedding sealantwithaninitialglue-linethicknessofa=0.05inwilldeformtothefollowingdimension:

c=(0.050)2+(0.055)2=0.074in• Thetotalmovementofthisglue-lineprofileduetoa40°F

changeintemperatureis:

Consulttheproductdatasheetforthemovementcapabilityratingofanyback-beddingsealanttodetermineiftheglue-line thickness tobeused is suitable for thedesignof thewindowunit.

FollowingASTMC719Standard Test Method for Adhesion and Cohesion of Elastomeric Joint Sealants Under Cyclic Movement (Hockman Cycle) protocol, the movementcapability forallDow Corning® InstantGlazeWindowAssemblyproductsis±50%.Usingtherelationshipbetween

7

Pythagorean theorem: a2 + b2 = c2

a = original glue-line thicknessb = joint movementc = deformed glue line after joint movement

b b

ca

a

Determining Sealant Glue-Line ThicknessTherequiredglue-linethicknessaforadifferentialmovement bcanbecalculatedusingthePythagoreanTheorem(Figure4). Likewise,theallowablemovementbforaparticularglue-line thickness acanbecalculated.Thedeformedglue-linedimensioncwillbelimitedbythemovementcapabilityofthesealantundergoingshearinthejointconfiguration.

Insulating Glass Unit

Sealant

Window Profile

a and casitrelatestomovementcapabilityM,themaximumvalueforccanbedetermined.

c=a(1+M/100%)Therefore,c=1.5aforaback-beddingsealantratedwith±50%movementcapability, and theminimumglue-linethicknessthatwillbeabletoaccommodateamaximumallowablemovementbduetoachangeintemperatureis:

a=b2/1.25Figure5showstheeffectofglue-linethicknessaonthemax- imum allowable movement b for a back-bedding sealantratedwith±50%movementcapability.

Movementdirectionshouldalsobetakenintoconsideration. Intheworstcasescenario,thermally-drivenmovementwill occurinonedirectionduetosettingblockspreventinganydownwardmovementoftheIGunit.Inasystemwherethe IGunitisnotsupportedbysettingblocks,theIGunitmay moveinbothdirections.

Somevariabilityinthewindowsashsurfaceflatnessshouldbeanticipated.Theprocessequipmentthatextrudestheseal-antbeadcanalsobeexpectedtodemonstratevariability.Hence,aminimumglue-linethicknessof0.035in(0.9mm)shouldbeobservedregardlessofthecalculations.

Glue-line thickness, in

0.00.035 0.050 0.075 0.100 0.125

0.04

0.02

0.06

0.08

0.10

0.12

0.14

Allo

wab

le jo

int m

ovem

ent,

in

Bite Calculation for Wind LoadAsidefromthermalstresses,thebondshouldbeabletoac-commodatedynamicloadsduetowind,impactfromflyingobjectsornormaloperationofwindows.Thefollowingprocedurescanbeappliedtocalculatetheminimumbite(contactwidth)necessarytosimultaneouslywithstandboththeweightoftheIGunitandanywindload.

Note: The provided bite calculations are guidelines and each window manufacturer should decide if additional structural support is needed to retain the IG unit based on knowledge of the specific finished product and intended application.

100%=48%0.050

0.074–0.050

Figure 5:Allowable jointmovementasa resultofachange in temperatureasafunctionoftheglue-linethicknessofaback- beddingsealantratedwith±50%movementcapability

Figure 4:Schematicdiagramsforthedimensionsusedtocalculate movementinthejointconfiguration.

8

ApplicationSafe Handling InstructionsBeforehandlingaDow Corning®InstantGlazeWindowAs-semblyproduct,reviewtheproductandsafetydatasheetsand the container label for safe use, physical and healthhazardinformation.Anyexposureofopenedcontainerstoair is discouraged because these productswill reactwith moistureintheatmosphereandbegintocureonthematerialsurface.The presence of local exhaust ventilation shouldbe discussedwith your safety department. Be aware thatairdraftsfromventilationsystemsintheproximityofthedispensingnozzlemayaffectitstemperature,whichwillinturn impactbead size consistencyand sealantwet-outonthewindowsash.

The product and safety data sheets are available fromdowcorning.com and www.instantglaze.com.Copiesmay alsobeobtainedfromyourlocalDowCorningSalesRepre-sentativeorDistributor.

RefertoIn-Shop Applicationofthedispensingequipmentforrecommendationsonthesafeoperationofthebulkmelter.

Theminimumsealantbitewnecessarytoresistagivenwindloadcanbeapproximatedusingthefollowingformula wherewandtheshorterdimensionofarectangularIGunithavethesameunitoflength(inormm),andwindloadand stresshavethesameunitofpressure.

Forexample,themaximumallowabledesignstressforDow Corning®InstantGlazeWindowAssemblyproductsis20psi(0.14MPa).Fora6ft×8ftIGunitwithanappliedwindloadof40psf,thesealantbitedimensionwillbe:

Toanticipatebeadsizevariabilityduringsealantbeadextru-sion,regardlessofthecalculationoutput,aminimumbiteof3/8in(9.5mm)shouldalwaysbeobserved.

Bite Calculation for Dead LoadTheweightoftheIGunitactsasadeadloadforthesealant bondwhenawindowisopened.ThefollowingformulacanbeusedtocalculatetheminimumbitedimensionwtoaccommodatethisdeadloadwheretheweightoftheIGunit isbasedonaglassdensityof0.090lb∙in3(2500kg∙m3)and gravitationalaccelerationis386in∙s–2(9.81m∙s–2).

Forexample, themaximumallowabledesignstress foraconstantloadforDow Corning®InstantGlazeWindowAssemblyproductsis1.0psi(0.007MPa).Fora3ft×5ftIG unit(192-inperimeter),theminimumbitedimensionforadeadloadof50lbfis0.26in(6.60mm).

Inalmostallapplications,theIGunitshouldbesupportedon the bottom by appropriately placed setting blocks perindustryacceptedpracticesfoundintheGlassAssociationofNorthAmerica(GANA)manual.WhereIGunitsaresupportedbysettingblocks,thesealantdoesnotexperienceanydeadloadandonlyexperiencesdynamicstressessuchasthermalandwindloadingconditions.

Setting BlocksSetting blocks are almost always required bywindowindustryIGmanufacturers.Alwaysensuresettingblocks incontactwith theDow Corning® InstantGlazeWindowAssembly products have been tested and approved forchemical compatibility.The primary function of settingblocks is thesupportofboth the inboardandoutboardlites of glass on the same horizontal plane.This ensures ashearingstressdoesnotoccurduetooneofthelitesbeing supportedonlybytheIGsealantsystem.ExcessiveloadingontheIGsealantsystemmayleadtofailureoftheIGsealandultimatelyIGfailure.BysupportingtheIGunitalong

thebottomwithaminimumoftwosettingblocks,verticalloadsintheIGunitaretransmittedentirelytothewindowsash for support.However, this practice results in thethermally-inducedmovementofboth thewindowsashandglasstobeintheverticaldirection.Sincemostwindowshave aspectratioswhereheightexceedswidth,thismovementisusuallythegreaterintheverticaldimension(height).

Typical YieldThe amount ofDow Corning® InstantGlazeWindowAs- semblyproduct required tomeeta targetmanufacturingnumberofwindowunitswill dependon thebead sizeofthesealantandtheperimeterlengthoftheunit.Oncebeadsizeandglue-linethicknessareestablishedbythewindowmanufacturer,Table2canbeusedasaguidetoestimatethelinealcoverageofagallonofsealantfordifferentbeadsizes.Thenumberof identicalwindowunits thatcanbemanufacturedpergallonofsealantcanthenbecalculatediftheperimeterlengthofthewindowunitisknown.

Table 2:Effectofbeadsizeonlinealcoveragepergallonofsealant

Initial Bead Size,1 inch

Linear Coverage per Gallon2

inches feet1/8 0.125 18,800 1,5003/16 0.188 8,400 6601/4 0.250 4,700 3803/8 0.375 2,100 170

1 Basedonacircularcross-section 2 Calculatedwithconsiderationtowasteduetostart-upandpurging

w= 2×MaximumallowabledesignstressShorterdimensionofIGunit×Windload

w= =0.50in2×20psi

6ft×12in/ft×40lbf /ft2×1ft2/144in2

w= PerimeterofIGunit×MaxallowabledesignstressWeightofIGunit×Gravitationalacceleration

9

Volatile Organic Content (VOC)• Non-hazardousformulation• LowVOC<15g/L

(exemptfromCaliforniaVOCregulations)

Product Handling Precautions

Theproductisgenerallydispensedaround248°F(120°C).Theuseofpersonalprotectiveequipmenttopreventcon-tactofhotmaterialorhotequipmentsurfaceswithskinoreyesisrecommended.

Safety Instructions

Safetyinstructionscontainedinthismanualapplytotasksthatmay be performedwithDow Corning® InstantGlaze WindowAssemblyproducts.Itisimportantthatthesesafety instructions are followed to protect employees, operators,andequipment.

• Becomefamiliarwithandfollowallsafetyinstructionsprescribedbyyourcompany,generalaccident-preven-tionregulationsandgovernmentsafetyregulations.

• Becomefamiliarwithandfollowallsafetyinstructionsprescribedbytheequipmentmanufacturers.

• Scheduleperiodicsafetyinspectionstoensurerequired materialandequipmentpracticesarefollowed.

• Provideappropriateemergencyandfirst-aidequipment intheproductionworkspace.

Recommended Personal Protective Equipment

Productanddispensingsystemarebothhotandpressurized.

• Safetyglasseswithsideshieldsorgoggles• Cut-resistantgloveswhenhandlingscrapersordeglaz-

ingtools• Glasshandlingjacketsand/orsleeves• Heat-resistant gloves to protect against burns when

workingwithhotmaterialsandequipment• Steel-toedshoeswhenhandlingproductcontainersand

windowunits

Quality ControlCustomersshouldexaminetheexpirationdate(EXPDATE)displayed on the packaging label to verify the product iswithin itsshelf life.Theseproductshaveashelf lifeof 12monthswhenstoredinaproperlysealed,air-tightcontain-erattemperaturesbelow90°F(32°C).Theproductshouldbeinspectedfortracesofcureuponopeningthecontainerforthefirsttime;refertothesectionDetermination of Cure State.Anyattempt topumpcuredmaterialwill impact beadqualityandcouldeventuallyleadtopumpdeteriorationandmalfunction.

Determination of Cure StateDowCorningpackages itsproducts incontainers thatareproperlysealed,buteventsmayoccur,suchasmishandlingofcontainers,thatmaycompromisetheintegrityoftheseal.Acompromisedsealmayallowairingressintothecontainer.Themoistureintheairwillproducethedetrimentaleffectofcuringthesurfaceoftheproductbeforeitcanevenbedispensedbythecustomer.

Dow Corning®InstantGlazeWindowAssemblyproductsdo notchangeinappearancebefore,duringoraftertheyarefully cured.The products undergo a change from a gum-likeconsistencyintheuncuredstateatroomtemperaturetoacross-linkedrubber-likematerialwhencured.

ToensurethatDow Corning®InstantGlazeWindowAssembly productscanbepumped,apicktestwasdevelopedtodetermineifthesurfaceoftheproductinitscontaineriscured(Figure6).

Usingascrewdriverorsimilartool,stabthesurfaceofthehot-meltproductandattemptto‘pick’up(remove)aportionofthematerial.ThetopphotographinFigure6showswhat willhappeniftheproductisuncured:thescrewdriverhead isabletopickupasmallamountofmaterialasthescrew-driverispulledquicklyawayfromthesurface.Thebottomphotographshowswhatwillhappeniftheproductiscuredattheexposedsurface:thesmallamountofmaterialthatispickedupbythetoolwillresistseparatingfromthebulkin

Good – Acceptable: Uncured product is gummy, separates easily and remains on the tool when pulled away from the surface.

Reject – Unacceptable: Cured product displays rubbery features, stretches and resists separation when pulled away from the surface.

Figure 6:DeterminationofthecurestateofDow Corning® InstantGlazeWindowAssemblyproductsusingapicktest

10

thecontainer.Anyoccurrenceofcureinthecontainerwillnotallowtheproducttobeproperlypumpedanddispensed.AvideoofthepicktestmaybefoundontheYouTubewebsiteat:www.youtube.com/watch?v=R95sUPaB_Hc.

Substrate PreparationDow Corning®InstantGlazeWindowAssemblyproductsdo notrequireprimers topromoteadhesiontocommonfene-strationsubstrates.Specialsurfacepreparationprocedures,suchassolventwiping,areusuallynotrequiredwhenap-plied toclean,drysubstrates.ThewindowmanufacturingprocessshouldthereforebesetupinamannerwhereinthewindowsashandIGarekeptcleanandfreeofdustandde-brispriortothesealantbeingapplied.Itisrecommendedtocleanthesubstratewhenindoubt.

When a cleaning solvent is used, the proper choice ofsolvent is an important part of the surface preparationrequirementsforsubstratesthataretobebonded.Cleaningsolventsdiffer ineffectiveness in removingcontaminants.Beawarethat theuseofaggressivesolvents likemethylethylketonecanadverselyaffectfinishessuchaspolyesterpowder-coatedaluminum.Mildercleaningsolventssuchas isopropyl alcohol (IPA) and high-quality (greater than98%purity)white/mineral spirits canbeusedwithoutdamagingthesubstratesurface.

BeforebeddinganIGunit,theglassedgeoftheouterpane mustalsobepreparedforbonding.Thisentailsensuringthe glassedgeiscleananddry.TheIGunitshouldbefreeofany cuttingoils,grease,dirtandotherformsofcontaminationwhichmightotherwisepreventproperadhesionandad- verselyimpactthelong-termdurabilityofthebond.

Dow Corning recommends checking with the substrate supplier and IGmanufacturer for the compatibility of cleaning solvents. Always follow manufacturer/supplier safehandlingrecommendationsaswellaslocal,stateandnationalregulations.

In-Shop ApplicationDispensing EquipmentDow Corning®InstantGlazeWindowAssemblyproductsaredesigned for dispensing from automated, high-volume bulkmelters (or hot-melt pumping systems) for 5-gallon/20-liter or55-gallon/200-litercontainers inconjunctionwithauto-matedroboticorhand-assistequipment.DowCorningcanprovideengineeringassistance in thedesignofadeliverysystem.Equipmentsuppliersofbulkmelterstypicallypro- videdesign,installation,operationandmaintenancetraining.

Hot-meltpumpscanberuneitherunderconstant floworconstantpressure.Dispensingproductunderconstantpressureusually leads tomoreconsistentflow.However,thiscanleadtoslightvariationsinflowwhenchangingcontainersduetobatch-to-batchviscosityvariations.To

maintainconstantvolumetricflow,thebestsolutionistorunthehot-meltpumpatconstantpressureandtoinstalla metering(gear)pumpjustbeforethenozzle.Thevolumetric outputdependsontemperatureandcanbeadjustedwiththe helpoftheequipmentsupplierandDowCorningtechnicalservicepersonnelduringthestart-upphase.

Thehose isan importantcomponentofapumpandgundeliverysystem.Theplanninganddesignoftheproductionareawherethesealantwillbeappliedshouldbefirsttakeninto consideration before selecting the appropriate hoselength and diameter.Hoses should be designed to be asshort inlengthandassmall indiameteraspossible,andmustnothavesomuchofapressuredropsoas tostarvethedeliveryofmaterialatanypointduringthedispensingphase.Hoses thatare too longand too large indiametercanmakemaneuveringthegunordispensingheaddifficult.Longerhoses requirehigherpressures tomaintain targetflowrates,andincreaseradiantheatloss.

Airflowaroundthedispensingnozzlewillbemuchcoolerthanthehot-meltmaterialexitingthehose.Variationsinambienttemperaturemayaffectbeadconsistencyunlessheatednozzlesareusedorthenozzlehasenoughbulktomaintainareasonablyconsistenttemperature.

Glazing TableAn automated X–Y glazing table is the most efficient method for applying glazing sealants to maintain beadconsistency,reducelaborandminimizewaste.ConsultyourDowCorningSalesRepresentativeforcontactinformationformanufacturers ofmelter and table equipment.Auto-matedglazingtablesapplysealantinthemostconsistentmanner,butproblemscanoccur.Routineoperationalauditsand preventivemaintenance schedules can help ensureconsistentsealantdelivery.

Toassistwith sealant applicationfilling issues, it isgoodpracticetohaveacompatiblesiliconesealantavailableincartridgeformthatcanbedispensedusingacaulkgunfor remedial glazing, or supplement sealant to thinly applied,shalloworskippedareasoftheglazedunitpriortobedding the glass.Dow Corning® 1199 SiliconeGlazing SealantClear,Dow Corning® 9-1350SiliconeGlazingSealant orDow Corning® 791SiliconeWeatherproofingSealant canbeusedinsuchsituations.

Manufacturing Process ConditionsDow Corning® InstantGlazeWindowAssembly productsdependonmoistureintheatmospheretocompletelycurethe sealant bead even though theyprovide instant greenstrength. The atmosphere in themanufacturing and anystagingareasshouldhaveaminimumrelativehumidityof30%andpreferably50–60%.Thecure rateof theseprod- uctswillbeaffectedastemperatureandrelativehumidityvaryduetonormalseasonalfluctuations.

11

The temperaturearound theglazingprocess shouldbewithin65°F(18°C)and90°F(32°C).Coldertemperatureswillreducecurespeedandadhesiondevelopment.Hottertemperatureswillinitiallyreducegreenstrengthandmaypromotesqueezeout;however,curespeedmayincrease.

Thesurfacetemperaturesoftheglassandwindowsashmust notfallsubstantiallybelowtherecommendedmanufactur- ingprocess temperature.Lower temperaturesmay lead to condensationorwetsubstratesurfaceswhichmayinfluence beadqualityorinhibitcure.

Themanufacturingenvironmentshouldbedustfree.

Dispensing TemperaturesThedispensingtemperatureiscriticalfortheproperappli-cation ofDow Corning® InstantGlazeWindowAssemblyproducts.Figure7showstheeffectoftemperatureonthehot-meltviscosityoftheseproducts,whichshouldnotbeexposedtosustainedtemperaturesabove285°F(140°C).

Table3listsrecommendedtemperaturerangesfordifferentzonesinthebulkmelterandisbetween248°F(120°C)and266°F(130°C).At248°F,theviscositiesofDow Corning® InstantGlaze II Sealant and Dow Corning® InstantGlaze III Adhesivearesimilarandapproximately75%lowerthanthat ofDow Corning®InstantGlazeSealant.Thesmallervolume zonesclosertothenozzlemaybesetathighertemperaturestoincreaseflowatthenozzlebutshouldnotexceed285°F(140°C).Thenozzletemperaturemayneedtobesethigherthan zone temperatures but should not exceed 285°F(140°C)dependingonairdrafts andheat losses from theuninsulatedmetalnozzle.Thisisgenerallyacceptablesince theresidencetimeofthehotmeltflowingthroughthenozzle isrelativelyshort.Maintainnozzletemperaturesatthelow-estpossibletemperaturewhichproducesconsistenthot-melt

Temperature, °F

Shear rate, s–1

Shear rate, s–1

Temperature, °C

0

0

0210

10

10

100

220

100

100

110

230

120

240

130

250 260 270

1000

1000

100,000

200,000

300,000

50,000

50,000

400,000

100,000

100,000

500,000

150,000

150,000

600,000

200,000

200,000

T = 120°C (248°F)

T = 130°C (266°F)

Visc

osity

, cP

Visc

osity

, cP

Visc

osity

, cP

Dow Corning® InstantGlaze Sealant Dow Corning® InstantGlaze SealantDow Corning® InstantGlaze II Sealant Dow Corning® InstantGlaze II SealantDow Corning® InstantGlaze III Adhesive Dow Corning® InstantGlaze III Adhesive

Table 3:Recommendedzonetemperaturesforhot-meltunloader

ZoneTemperature

°F °CPlaten 248 – 266 120 – 130Hose 248 – 266 120 – 130

Gun body/valve 248 – 266 120 – 130Metering pump 248 – 266 120 – 130

Nozzle1 248 – 285 120 – 1401 Mayexceed266°F(130°C)dependingondrafts,ambienttemperatureandheatlossthroughthenozzle.

flowandbeaddimensions.Takeadvantageofanyequipmentoperational safety feature thatwill protect thehot-meltproductfromoverheating.Thiswillalsoextendtheservicelifeofo-ringsandsealsusedinthedispensingequipment.

The hot-melt viscosity ofDow Corning® InstantGlaze WindowAssemblyproductswillalsodependonshearrate, whichisproportionaltothevolumetricflowratecomingoutofthenozzle.Figure8showshowthehot-meltviscosity changeswithshearrateat120°C(248°F)and130°C(266°F). ForthesealantbeadsizeslistedinTable2,theshearratecanbeexpectedtovarybetween10and200s–1inthehose andbetween100and1,000s–1inthenozzle.

Figure 7: Effect of dispensing temperature on the hot-melt viscosityofDow Corning®InstantGlazeWindowAssemblyproducts (1,000cP=1,000mPa∙s=1Pa∙s)

Figure 8:Effectof shear rateon thehot-meltviscosityof Dow Corning® InstantGlaze Window Assembly products at120°C(top)and130°C(bottom).1,000cP=1,000mPa∙s=1Pa∙s

12

Dispensing Too HotCaution: Maintaining the material at temperatures over 266°F (130°C) over extended periods of time may have the following detrimental effects:

• Reduced tackiness• Beaddraggingaroundthecorners• Bubbles in sealant• Reducedpotlife• Excessivefluidity

Dispensing Too ColdOperatingattoolowatemperaturewillincreasetheviscosity, leadingtopredictableproblems:

• Difficultypumping• Unevenflowfromnozzle• Build-upofmaterialon thesideof thenozzlecausing

offsetdispensing• Stringinessbehindthenozzle

Draftsoratmosphereslowerthantypicalroomtemperatures [65°F (18°C)] may contribute to adverse dispensingperformanceatthenozzletip.

After a Dow Corning® InstantGlaze Window Assemblyproducthasbeendispensedat248°F(120°C),itwilltakeapproximatelyfiveminutesforthebeadtocooldowntoambienttemperatures.Figure9showstypicalchangesinbeadtemperatureasafunctionoftimeelapsedafterwettingouttypicalwindowsashsubstrates.Thetemperatureprofiledepends on the thermal conductivity of the substrate(s);for example,wood andPVC (and silicones) have similarthermalconductivities(~0.2W∙m–1∙K–1)comparedtowin-dowglass(~1W∙m–1∙K–1)andaluminum(~200W∙m–1∙K–1).

Glazing Process• Opentimeisdefinedasthemaximumelapsedtimeafter

dispensingthesealantforcompletingallmanufacturingstepsoneachunit.Dow Corning®InstantGlazeWindowAssemblyproductshaveupto15minutesopentimeatroom temperature.Thisprovidesprocessingflexibilityandrobustmanufacturingoptions.The15-minuteopentimeallowstheglasstoberealignedorreworkedduringinstallation,andallowsinstallationofsettingblocksandspacers,aswellasopposite-sideglazingbeadsandothercomponents,withoutadverselyaffectingthepropertiesofthesealant.

• Oncesealantisappliedtothewindowsash,theglass,settingblocksandspacersshouldbeinstalledandposi-tionedwithin15minutes.Ifthesealantisleftforlongerthan15minuteswithouttheglassbeinginstalled,thesealantshouldberemovedfromthewindowsashandafreshbeadshouldbeapplied.

• Ensuretheglassisbeddeddirectlyonthesealantandnotboundindirectcontactwiththewindowsash.

• Installsettingblocksandspacerstocontrolthepositionoftheglassinthewindowsash.Toallowforplacementof setting blocks, glassmay be shifted slightly if nec-essarybyapplyingaslow,steadyforcewithathin,hardplastic spatula. If glass shifting, repositioning or anyreworkingisrequired,itshouldbedonewithinthefirstfiveminutesafterdispensingthesealant.

• Applyopposite-sideglazingbeadsprior to leaning the windowaway from the sealant. If productionwill not allowforthis,storethewindowuniteitherflatorwith theweightoftheglassleaningonthesealant.

General Considerations for Applying Dow Corning® InstantGlaze Window Assembly SealantsFollow themanufacturer recommendations formaterialdispensingandpumpoperation.

Initial Start-Up Tips• Disconnectthehoseattheglazingtableandpositioninto

an emptydrum to capturepurgematerial and ensureallcontaminants(suchasassemblylubricantsandtestfluids) are cleared from the pumps and hoses prior toproceedingwithproduction.

Elapsed time, min

Elapsed time, min

40

40

0

0

1

1

2

2

3

3

4

4

5

5

100

100

30

30

10

10

50

50

160

160

70

70

90

90

220

220

110

110

Hot

-mel

t bea

d

tem

pera

ture

, °F

Hot

-mel

t bea

d

tem

pera

ture

, °F

Hot

-mel

t bea

d

tem

pera

ture

, °C

Hot

-mel

t bea

d

tem

pera

ture

, °C

PVC

PVC and glass

Wood

Wood and glass

Aluminum

Aluminum and glass

Figure 9: Typical changes in bead temperature as a functionoftimeelapsedafterwettingouttypicalwindowsashsubstrates(top)andwhensqueezedbetweensubstrateandglass(bottom)

13

• Reconnectthehoseandbeginpurgingmaterialthrough the nozzle.Collectmaterial into a suitablewaste con-taineruntilallvisiblecontamination,suchasoilsand/orairbubbles,areno longerpresentandmaterial isextrudingsmoothlyfromthenozzle.

• Run test beads of material to ensure uniform beadapplicationonthesubstrate.

Container Changeover

• Testanewlyopenedcontainerforcure.RefertothesectionDetermination of Cure State.

• Ensurethefollowerplateniswipedfreeofdirt,dustoroilspriortopumpingmaterial.

• GreasethegasketonthefollowerplatenwithMolykote® 111 Compound (or other silicone-compatible, high-temperaturegreases).

• Afteropeningandtestingforcure,place thecontainer undertheheatedplaten.

• Opentheventvalveontheplatentoallowtrappedairtopurgefromthecontainerastheplatenisbeingloweredintothecontainer.

• Starttheheatcycleandwaitfortheplatentoreachthe targetdispensingtemperature.RefertothesectionDis- pensing Temperaturesformoreinformation.

• Apply down-force pressure (make sure the directionswitchforplatenisinthedownposition)andpurgeanyremainingairthroughtheventvalve.Itisrecommendedthatanypurgedmaterialbecollectedinasuitablewastecontainerforproperdisposal.

• Shuttheventoncehot-meltmaterialisflowingthrough theventvalvewithnoairbubbles.

• Startthepumptobegindispensingthematerialthrough thenozzle.Collectmaterialinasuitablewastecontaineruntilmaterialisrunningsmoothly.

• Run test beadsofmaterial to ensureuniformbead ap-plicationonthesubstrate.

Time at Temperature Considerations• Inasealedsystem,Dow Corning®InstantGlazeWindow

Assemblyproductsarestableforupto24hoursat248°F (120°C).Iftheglazingprocessisnottobeusedforanextendedperiod,uptoandincluding24hours,thepumpsandheatingzonescanbeshutdownorthetemperaturesloweredwithoutdetrimentaleffectsonthesealant.

• Forshutdownintervalsinexcessof24hours,poweringdown theequipment is required.Provided theproductremainssealedwithinitscontainerandequipment,the pumpcanberestartednormallywithoutaffectingmaterial. Approximateheat-uptimeis30to60minutesdepending onequipmenttypeandmanufacturerrecommendations.

• Exposureofopenedcontainerstoairshouldbeminimized because Dow Corning®InstantGlazeWindowAssemblyproductswillreactwithmoistureintheatmosphere.

Shut Down Considerations• Nozzle tips left exposed to air after shutting down

production will cure any hot-melt product left overwithinthenozzle.Attheendofaproductionrun,applyMolykote®111Compoundtothenozzletip.Immersionof thenozzle tip inanyviscositygradeof siliconeoilwillalsowork.Uponstart-up,smallamountsofcuredmaterial from within the nozzle tip can usually bedispensedduringthepurgecycle.

• Forshutdownintervalsinexcessof24hours,powering downtheequipmentisrequired.Thiswillsaveenergy, extend the service life of the o-rings and seals in thedispensing equipment and avoid exceeding productpotlife.Removethenozzlewhilewarmanduseapipe plugtocaptheapplicationheadandthehose.

• Providedtheproductremainssealedwithinitscontainer and equipment, the pump can be restarted normallywithoutanyadverseeffects.

Quality Control and Application IssuesBead Location• Thesealantbeadshouldbe locatedon theglazing leg,

parallelwiththeglazingleg,andwithinthedimensionsoftheglassunit.

• Beadlocationsnotparalleltotheglazinglegoroutside of the dimensions of the glass unit may not contact theglassatsomelocationsoftheglassperimeter.

• Otherissuesthatcouldcausebeadlocationerrorsmay includetheoperatornotplacingthewindowsashsquare-lyonthetableorthetablenotʻseeingʼorsensingthewindowsashproperly.

Bead Consistency and UniformityBead consistency and uniform bead dimensions areimportant for good sealantwet-out and consistent bite.Theconsistencyof thebeadmustbecheckedoneverywindowsash. Ifbead inconsistenciesoccur,determiningandcorrectingtherootcausewillbenecessary.Asidefromthenozzleopening,flowrate–pumppressure,andtablespeedwilldefinebeadsize.Ifthebeadsizeisinconsistent,thismayindicateachangeinpumppressure,temperaturevariationsespeciallyat thenozzle tip, improperlysizedhoses,oraproblemwiththepump.

Below are some examples of bead inconsistencies andsuggestedremedies.

Skip–AnareawheretheX–Yglazingtabledoesnotapply anyback-beddingsealant:

• Apply Dow Corning® 1199 Silicone Glazing SealantClear(orothersealants,suchasDow Corning® 9-1350 SiliconeGlazingSealantorDow Corning®791Silicone WeatherproofingSealant)totheskiplocation.

14

Thinning –An area along the sealant linewhere the beaddimensionisunusuallythinandnon-uniform:

• Apply Dow Corning® 1199 Silicone Glazing SealantClear(orothersealants,suchasDow Corning® 9-1350 SiliconeGlazingSealantorDow Corning®791Silicone WeatherproofingSealant).

• Check that the dispensing pump is powered on andmaintaining pressure. If thinning occurs at the end ofthecycle,thiscouldbeanindicationthateitherthe system has too much pressure drop for the flow rate required or the melt rate of the bulk melter is notsufficientfortheapplicationrate.

Tooling–Anareaalongthesealantwherethenozzlewastoo low(orthewindowsashtoohigh)andthenozzledraggedonthesealant:

• Scrapeoffthesealantandapplynewsealant.• Adjustthenozzletotheappropriateheight.

Waviness or unevenness–Aninconsistentbead thatcanoccurwhenthenozzleistoohighabovethewindowsash:

• If the waviness results in a bead of varying heightcausingwet-out to be inconsistent, scrape off the bead and reapply. If the bead is just uneven, but the bead height is consistent, the sealant application is acceptable if the window manufacturer deems the waviness to bevisuallyacceptable.

• Adjustthenozzletotheappropriateheight.

Substrate Issues: Uneven Surfaces in Window SashUnevensurfaces,suchasimpropercleaningofweldedcornersorawarpedwindowsash,cancauseeithertoolingorwavysealantandcancontributetoaunitthatmaybeimproperlysealed.It isvital toconsistentlyprovideaflat,evenwindow sash onwhich to apply theDow Corning® InstantGlazeWindowAssemblyproduct.

Equipment IssuesIssuesmay occur evenwhen following recommendedoperational andmaintenance practices. Some of theseissuesmayadverselyaffectthequalityofthesealantbeadbeingappliedonthewindowunit.

Application Head or Nozzle• Thenozzleontheapplicationheadisoftenuninsulated.

Nozzle temperaturesareoften sethigher thanhosetemperatures,butshouldnotexceed285°F(140°C) tomaintainconsistenthot-meltflowandbeaddimensions. Thisisgenerallyacceptablebecausetheresidencetimeofthehot-meltflowingthroughthenozzleisshort.

• Anozzle tip leftexposed toairduringproductiondowntimeswillcureanyhot-meltproductleftoverwithinthe nozzle.At theendofaproductionrun,applyMolykote®

111 Compound to the nozzle tip. Immersion of thenozzle tip in any viscosity grade of silicone oil willalsowork.Removenozzlewhilewarmanduseapipeplug to cap the application head when productiondowntimesexceed24hours.Nozzles containing curedmaterial can often be purged outwith freshmaterial. Occasionally, the nozzlemayneed to be removed and cleaned or replaced if the material curehasprogressed toodeep.Dow Corning® 3522 Cleaning Solvent, which is based on odorless mineralspirits,maybeusedtodissolvecuredsilicones.

Hose

Pluganyopen-endedhosewhenproductiondowntimesex-ceed24hoursormaterialmaystarttocureandaffectflowinsubsequentproductionruns.Dow Corning® InstantGlaze WindowAssemblyproductsdonotbuildupontheinteriorhosewall, andpropercareof theoutsideof thehose in- cluding preventing excessive tight radius bending shouldleadtoalonghoselifeaslongasthesealantisnotallowedtocureontheinside.

Melt Platen Sealing RingsAvoidbuildupofproductresidueonthemeltplatensurfaceand around the sealing rings. Any residue should beconsideredcuredandwillreducetheseal’seffectiveness.Avoidtheuseofsharptoolsandremoveanyresiduebeforestart-uporwhenanewcontainer is loaded.Followallrecommendationsforlubricatingthesealingrings.Insomeinstances,thesealingringmayneedtobereplaced.

LeakageWhenairorsealantleakageoccurs,immediatelyreplacethe correspondingsealoro-ring.

Compressed Air

Compressedairisusedforpneumaticoperationsincludingtheaerationanddeaerationofthecontainer.Compressed aircomingintocontactwiththemoisture-reactiveproduct mustbecleananddry.

Environmental IssuesAirdraftsfromventilationsystemsintheproximityoftheapplicationheadmayaffectitstemperature,whichwillinturnimpactbeadsizeconsistencyandsealantwet-outonthewindowsash.Reduceandeliminateairflowonnozzleswherepossible.

Temperature and humidity conditions in themanufacturing areashouldbecontrolledyearroundifpossible.Likeother one-partRTVsealants,DowCorning®InstantGlazeWindow Assemblyproductsrequiremoistureintheairtocure.

15

Deglazing and Reglazing of Window UnitsNote: It is recommended that the operator wear appropriate Personal Protection Equipment while deglazing any window and handling glass.

Deglazingcanbeusedtoremedymanufacturingissuesassociatedwiththeback-beddingsealantand/orasaquality assurance method of inspection used to confirm goodadhesionandproperfilloftheglazingjoint.

WindowunitsmanufacturedwithDow Corning® InstantGlaze WindowAssemblyproductsastheback-beddingsealantcan bedeglazedusingstandarddeglazingtools.

Toremedyamanufacturingissue,thewindowshouldbe deglazedwithin thefirst30minutesof assemblyby re-movingopposite-sideglazingbeadsandapplyingsteadypressureonacorneruntilthesealantbreaks.Next,carefullyapplypressurearoundtheperimeterof theunituntil theglassisfree.

Forcuretimesexceedingonehour,itmaybenecessaryto cuttheglassoutoftheunitusinganappropriatetoolsuchasthatshowninFigure10.First,removetheopposite-side glazingbeadsifthesearepresent.Deglazethewindowby sprayingtheperimeteroftheunitwithamildsolvent,such asisopropylalcohol(IPA),tosoftenthesealantandprovide lubricationduringcutting.Insertthecuttingtoolbetweenthe glazinglegonthewindowsashandtheglass.Workingthe bladebetweenthesetwosurfacesisthemostcriticalstep;itispossibletobreaktheglassifexcessivepressureisapplied.Oncethebladeiswellpositionedbetweentheglassandtheglazingleg,moveitslowlyaroundthewindowcuttingthesealant line and finally removing the IG unit.MultiplepassesaroundtheunitandadditionalapplicationsofIPA mayberequiredtocompletelycuttheunitfree.

Anoperatorshouldstand inanergonomicpositionas to beabletoinsertthebladeandmoveitaroundthewindowwithoutreachingwellbeyondtheirrangeofmotion.

Deglazingcanbeusedasatestforqualityassurance.During productionofwindowunits,itisagoodideatoperiodically

monitor sealant performanceand application.Quality assur-ancetestsaregoodpracticeandcanalert themanufacturer toapotential quality issue prior tomanufacturing a large quantityof units. It is the prerogativeofthewindowmanufacturertodeterminethefrequencyofanytest including deglazing basedonqualityassuranceprinciples.

Whenusedasaqualityassuranceprocedure,unitsshouldsitfortheprescribedcuretimebeforedeglazingtocheckfor beadquality.Thesealantshouldbeinspectedforwet-outto boththeliteandthewindowsash.Forbestinspectionresults, the surface of the lite and/orwindow sash should not bedamaged.Theinspectionshouldincludethefollowing:

• Uniformityofwidthofsealantbite• Wetoutofsealantontheliteandwindowsash• Uniformityofcure• Appearanceofsealant,includinguniformityofcolor

for pigmented versions and presence of bubbles orforeignmatter

Shop ReglazingWindowunitsoriginallyglazedwithsiliconesealantsshould bereglazedwithsiliconesealants.Glazingtapeswillnot adheretoaglazinglegthathashadasilicone-basedmaterial previouslyappliedtoit.

Oncetheglassisremovedfromthewindowsash,scrapeawayexcessbeadsof sealantusingaputtyknifeoraspatulawithafinelygroundsharpblade.Awideflat-headscrewdriverisfrequentlyused.Itisunnecessarytocleantheglazinglegwithanychemicalortoremovethesealantfilm.Reapply Dow Corning® InstantGlaze WindowAssembly producttotheglazinglegandfollowregularglazinginstal-lationprocedures.

Field ReglazingDow Corning®InstantGlazeWindowAssemblyproductsare100%silicone:othercold-appliedsiliconesealantsarecompatibleandwilladheretoit.Oncetheglassisremovedfromthewindowunit,scrapeawayexcessbeadsofsealant.Itisunnecessarytocleantheglazinglegwithanychemicalortoremoveanyleftoverfilmfromthesealantbead.

Apply a fresh sealant bead to each glazing leg usingeither Dow Corning®1199SiliconeGlazingSealantorDow Corning® 791 Silicone Weatherproofing Sealant.Immediately install the new IG unit (before a sealantskin forms) and reinstall opposite-side glazingbeads andother components as needed according to the windowmanufacturer’sprocedures.

Finished Unit RecommendationsAvoidprolongedexposure tocitrus-containingcleaners,solventsandsolvent-basedcleanersastheymaydamagethecuredsealant.

Figure 10:Deglazingtool

16

Frequently Asked QuestionsComparative PerformanceQ:

A:

Q:

A:

Q:

A:

Q:

A:

Green StrengthGreenstrengthcanbedescribedastheinitialshearstrength beforeasealantexhibitssignificantcureastobuildmech-anicalandadhesionstrength.TheDowCorningCorporateTestMethod(CTM)02431isusedtomeasuretheamountofshearforcerequiredtoseparateasingle-lap-jointlaminateunderambientconditions.A0.10-inglue-linethicknessisusedbetweena1×1in2overlapofmill-finishedaluminumsubstrates, which are pulled apart along its long axis at 2 in∙min–1afterpredefinedcure intervalsat24±2°Cand 50±5%RH.Theresults forDow Corning® InstantGlaze WindowAssemblyproductsareshowninFigure11.

Adhesion-in-Peel StrengthTheabilityofacuredsealanttomaintainanadhesivebond toaparticular substratewhile subjected toa180°peel is evaluatedusingamodifiedversionofASTMC794Stand-ard Test Method for Adhesion-in-Peel of Elastomeric Joint Sealants.Dow Corning® InstantGlazeWindowAssemblyproducts exhibitpeel strengthsof at least30pli after a 7-daywaterimmersiontoavarietyofcommonsubstrates.RefertothesectiononSubstrate Selection.Themodeoffailureiscohesive.

• Dow Corning® InstantGlazeSealant>45pli• Dow Corning® InstantGlazeIISealant>41pli• Dow Corning® InstantGlazeIIIAdhesive>30pli

Elapsed time after assembly

015 min 1 hour 4 hours 1 day 3 days 7 days 21 days

10

20

40

30

60

50

Gre

en s

treng

th, p

si

Dow Corning® InstantGlaze SealantDow Corning® InstantGlaze II SealantDow Corning® InstantGlaze III Adhesive

Figure 11:GreenstrengthbuildupofDow Corning® InstantGlaze WindowAssemblyproductsconfiguredwitha0.10-inglue-linethicknessinasingle1×1in2overlaplap-shearjointat24±2°Cand50±5%RH

1 CTM 0243 is based onASTM C961 Standard Test Method for Lap Shear Strength of Sealants and ASTM D1002 Standard Test Method for Apparent Shear Strength of Single-Lap-Joint Adhesively Bonded Metal Specimens by Tension Loading (Metal-to-Metal).

What are the handling precautions for DowCorning® InstantGlaze Window Assembly products?

Beforehandling, readproductandsafetydata sheetsandthecontainerlabelforsafeuse.Exposureofopenedcontainerstoairisdiscouragedbecausetheseproductswillreactwithmoistureintheatmosphere.Theproductisdispensedunderpressureat approximately248°F(120°C), and use of personal protective equipment topreventcontactwithskinoreyesisrecommended.

Is any local exhaust ventilation required?

Dow Corning® InstantGlazeWindowAssemblyprod- uctshavea lowvolatileorganiccontentof less than15 g/L.The need for local exhaust ventilation shouldbe discussed with your safety department personnel.An exhaust hood can be integrated into the design ofthe bulk melter to remove vapors directly from thecontainer.Refer to theproduct and safetydata sheetsforfurtherinformation.

DowCorning has an extensive Product StewardshiporganizationandateamofProductSafetyandRegula- toryCompliance (PS&RC) specialists to support cust-omersforproductsafetyneeds.Forfurtherinformation,please see ourwebsite, dowcorning.com, or consultyourlocalDowCorningSalesApplicationEngineer.

What purge material can be used to clean existing material from dispensing equipment before using DowCorning® InstantGlaze Window Assembly products?Dow Corning recommends retrofitted hot-melt pump-ingequipmentbedisassembled,cleanedandrebuilt if ithasbeenusedwithothertypesofhot-meltmaterials(e.g. acrylics, butyls, urethanes). Dispensing hosesshouldbereplaced.Dow Corning®3522CleaningSol- vent,basedonodorlessmineralspirits,maybeusedas apurgematerial and shouldbe appliedat room tem-perature.Ifyouneedtopurgelines,contactyourlocalDowCorningrepresentative.

How shall I conduct incoming product inspection?Non-pigmentedDow Corning® InstantGlaze Sealant andInstantGlazeIISealantareclear,butDow Corning® InstantGlaze IIIAdhesive appears translucent in its bulkform.Atypicalbeadofanynon-pigmentedsil-icone hot-melt productwill appear optically clear fordesirableaesthetics.

Thematerial,beforepumping,shouldbepliablebutnotstretchy.Astretchyresponseisanindicationofacuredsurfaceduemost likely to theproductcontainersealbeingcompromised.RefertothesectionDetermination of Cure Stateformoreinformation.

17

Q:

A:

Q:

A:

Q:

A:

Q:

A:

Q:

A:

Sealant Profile Calculation InputsLargest window height: ___________________________

Largest window width: ___________________________

IstheIGunitsupportedatthebottombysettingblocks?YesNo

IftheIGunitisnotsupportedbysettingblocks,maximumweightofIG:____________________________________

Iftheunitiswiderthanitistall,istheIGunitfreetomoveinbothhorizontaldirections?YesNo

Shoptemperatureduringfabrication:_________________

Expectedmaximumwindload:______________________

Sashmaterial: AluminumWoodVinylFiberglass Other: _________________________________________

ExpectedactualLOWtemperatureofsash,atsealantbond,duringservice:___________________________________

Expected actual HIGH temperature of sash, at sealantbond,duringservice:______________________________

Expected actual LOW temperature of glass, at sealantbond,duringservice:______________________________

Dow Corning®SealantchoiceORmovementcapabilityofselected sealant: _________________________________

How do I clean DowCorning® InstantGlaze materials off my equipment and tools?

Isopropylalcoholcanbeappliedtoareaswhere thesealant needs to be removed. This will soften thecuredmaterialandallowit tobescrubbedawaywithan abrasive pad.TheDow Corning® 3522CleaningSolvent,whichisbasedonodorlessmineralspirits,mayalsobeusedtoremovecuredsilicones.

What bead size is recommended?

Manufacturers designing and testing fenestration sys-temsshoulddeterminebeadsize thatwillprovide therequired sealantbiteandglue-line thickness.Refer tothesectionSealant Design Considerationsformoreinformation.

What can be done if the table skips or there is a gap in the sealant bead?Dow Corning®1199SiliconeGlazingSealantClearcanbeusedtopatchgapsinthesealant.Othersiliconesinuse inyourfacilitymayalsobeused(e.g.,Dow Corning® 9-1350SiliconeGlazingSealantorDow Corning® 791 SiliconeWeatherproofingSealant).RefertothesectionBead Consistency and Uniformityformoreinformation.

Are DowCorning® InstantGlaze Window Assembly products compatible with clean glass?Dow Corning® InstantGlazeWindowAssembly prod-uctsareapprovedforusewithPPGSunclean™ Glass according to PPG. Non-pigmentedDow Corning® InstantGlazeproductsdonotcontainsiliconeoils thatcan migrate to the glass, and exhibit ʻnegligible silleffectʼ and ʻnegligible picture framingʼwhen used inback-beddingapplications.

When should setting blocks be used?

DowCorning recommends that settingblocks are al-ways used based on Insulating GlassManufacturersAlliance (IGMA) and GANA guidelines. In addition to setting blocks, side placement shims may be re- quiredtoholdtheIGunitinplaceintheeventthatthewindow unit is tilted on its side during production orshipment.Consult the IGmanufacturer for additionalsupportrequirements.

Images:Cover–AV19723;Page15– AV21255

LIMITED WARRANTY INFORMATION - PLEASE READ CAREFULLY

Theinformationcontainedhereinisofferedingoodfaithandisbelievedtobeaccurate.However,becauseconditionsandmethodsofuseofourproductsarebeyondourcontrol,thisinformationshouldnotbeusedinsubstitutionforcustomer’steststoensurethatourproductsaresafe,effectiveandfullysatisfactoryfortheintendedenduse.Suggestionsofuseshallnotbetakenasinducementstoinfringeanypatent.

DowCorning’s solewarranty is that our productswillmeet the sales specifications in effect at the time ofshipment.

Yourexclusive remedy forbreachof suchwarranty is limited to refundofpurchasepriceor replacement ofanyproductshowntobeotherthanaswarranted.

TO THE FULLEST EXTENT PERMITTED BY APPLICABLE LAW, DOW CORNING SPECIFICALLY DISCLAIMS ANY OTHER EXPRESS OR IMPLIED WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE OR MERCHANTABILITY.

DOW CORNING DISCLAIMS LIABILITY FOR ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES.

Dow CorningisaregisteredtrademarkofDowCorningCorporation.MolykoteisaregisteredtrademarkofDowCorningCorporation.We help you invent the futureisatrademarkofDowCorningCorporation.SantopreneisaregisteredtrademarkofExxonMobil.KratonisaregisteredtrademarkofKratonPolymers.Sunclean and DuranarareregisteredtrademarksofPPGIndustriesOhio,Inc.KynarisaregisteredtrademarkofArkema,Inc.

©2014DowCorningCorporation.Allrightsreserved.

30018910 63-1038B-01