mitra rigid supports - ud artcons supports.pdf · artists - rigid supports there are pros and cons...

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MATERIALS INFORMATION and TECHNICAL RESOURCES for ARTISTS - Rigid Supports There are pros and cons to all solid and flexible supports. Generally speaking, an ideal support will be able to withstand fluctuations in RH and temperature, possess an adequate level of absorbency and/or tooth, remain planar and resist warping, and not become brittle or fragile with age. One drawback often associated with flexible supports is that they are more susceptible to being damaged by physical impact (e.g. tears, impact cracks, punctures, etc.) Flexible supports made from cellulose like cotton and linen are more likely to respond to changes in the environment, giving rise to draws in the corners, an overall loss of tension, and other planar deformations. Such damages can lead to both short and long term condition issues and can affect the stability of the paint and ground layers. Because of these issues, artists are highly encouraged to affix protective backing boards to the reverse of their paintings. This helps to prevent physical impacts from the reverse and help to buffer and slow the fabric’s response to changes in humidity. Rigid supports made from hygroscopic materials like wood are less likely to withstand physical damage but will still react to changes in the environment (e.g. warping, cracking, etc.) which can adversely affect the ground and paint layers. There are steps that artists can take to mitigate some of these problems. One method is to adhere a fabric support over the face of the rigid panel. The fabric can serve as a less brittle interlayer which may stop the crack or split from telegraphing from the support to the ground and paint layers should the rigid support exhibit warping and/or cracking. Rigid supports can also be cradled or braced, particularly if they are large in size, to counteract possible warping or other types of planar deformations. RIGID SUPPORTS Many different solid support materials are available to artists. These materials include wood, metal, and modern composite materials. As there are pros and cons associated with any choice of solid support, artists should keep in mind the size, ground, and paint layers that will be applied when selecting and preparing their substrates. The following is information about a number of types of solid supports that are currently available to artists. Additional information on historical and contemporary practices relating to rigid supports is available in the section containing online resources and references. Solid Wood Panels For centuries painters have used hardwoods (from deciduous trees and narrow-leaved evergreens) and semi-hardwoods (partially matured cuttings from deciduous trees) including oak, mahogany, chestnut, and poplar have been used as

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Page 1: MITRA Rigid Supports - UD ArtCons Supports.pdf · ARTISTS - Rigid Supports There are pros and cons to all ... Rigid supports made from hygroscopic materials like wood are ... including

MATERIALSINFORMATIONandTECHNICALRESOURCESforARTISTS-RigidSupports

Thereareprosandconstoallsolidandflexiblesupports.Generallyspeaking,anidealsupportwillbeabletowithstandfluctuationsinRHandtemperature,possessanadequatelevelofabsorbencyand/ortooth,remainplanarandresistwarping,andnotbecomebrittleorfragilewithage.

Onedrawbackoftenassociatedwithflexiblesupportsisthattheyaremoresusceptibletobeingdamagedbyphysicalimpact(e.g.tears,impactcracks,punctures,etc.)Flexiblesupportsmadefromcelluloselikecottonandlinenaremorelikelytorespondtochangesintheenvironment,givingrisetodrawsinthecorners,anoveralllossoftension,andotherplanardeformations.Suchdamagescanleadtobothshortandlongtermconditionissuesandcanaffectthestabilityofthepaintandgroundlayers.Becauseoftheseissues,artistsarehighlyencouragedtoaffixprotectivebackingboardstothereverseoftheirpaintings.Thishelpstopreventphysicalimpactsfromthereverseandhelptobufferandslowthefabric’sresponsetochangesinhumidity.

Rigidsupportsmadefromhygroscopicmaterialslikewoodarelesslikelytowithstandphysicaldamagebutwillstillreacttochangesintheenvironment(e.g.warping,cracking,etc.)whichcanadverselyaffectthegroundandpaintlayers.Therearestepsthatartistscantaketomitigatesomeoftheseproblems.Onemethodistoadhereafabricsupportoverthefaceoftherigidpanel.Thefabriccanserveasalessbrittleinterlayerwhichmaystopthecrackorsplitfromtelegraphingfromthesupporttothegroundandpaintlayersshouldtherigidsupportexhibitwarpingand/orcracking.Rigidsupportscanalsobecradledorbraced,particularlyiftheyarelargeinsize,tocounteractpossiblewarpingorothertypesofplanardeformations.RIGIDSUPPORTS

Manydifferentsolidsupportmaterialsareavailabletoartists.Thesematerialsincludewood,metal,andmoderncompositematerials.Asthereareprosandconsassociatedwithanychoiceofsolidsupport,artistsshouldkeepinmindthesize,ground,andpaintlayersthatwillbeappliedwhenselectingandpreparingtheirsubstrates.Thefollowingisinformationaboutanumberoftypesofsolidsupportsthatarecurrentlyavailabletoartists. Additionalinformationonhistoricalandcontemporarypracticesrelatingtorigidsupportsisavailableinthesectioncontainingonlineresourcesandreferences. SolidWoodPanels

Forcenturiespaintershaveusedhardwoods(fromdeciduoustreesandnarrow-leavedevergreens)andsemi-hardwoods(partiallymaturedcuttingsfromdeciduoustrees)includingoak,mahogany,chestnut,andpoplarhavebeenusedas

Page 2: MITRA Rigid Supports - UD ArtCons Supports.pdf · ARTISTS - Rigid Supports There are pros and cons to all ... Rigid supports made from hygroscopic materials like wood are ... including

supports.Thelong-termageingpropertiesofsolidwoodpanelsdependonthetypeandcutofwood.Sapwoodistheoutermostportionofatreetrunk(thelivingpartofthetree),whileheartwoodisthetrunk’sinner(dead)core.Heartwoodismoresuitableforuseforpaintingsupportsasitshrinksandswellslessthansapwood.Allsolidwoodpanelsaresusceptibletosomedegreeofwarping,shrinkageorexpansion.Thiscanbelessenedbytheselectionofthemoreappropriatecutsofwood(radialratherthantangential),properpreparation(ageinganddrying)ofthewoodensupport,andthemethodoftreatment(finishingbothsidesofthepanelinasimilarmanner).Sometypesofwoodaremorelikelytoexperienceattacksbywood-boringinsects.Thisshouldbetakenintoconsiderationwhenselectingandpreparingawoodensupport.

Page 3: MITRA Rigid Supports - UD ArtCons Supports.pdf · ARTISTS - Rigid Supports There are pros and cons to all ... Rigid supports made from hygroscopic materials like wood are ... including

Thestabilityofawoodenboardisgreatlyinfluencedbywhereitwascutfromtheoriginaltreetrunk.Woodexpandsandcontractsinthedirectionperpendiculartothegraindirection.Woodenboardstendtobemoststablewhentheyaremostsimilaronthefrontandback.Tangentiallysawnplanksarepronetoplanardeformationslikewarping,splitting,andcrackingastheseplanksoftencontainbothsapwoodandheartwoodandthenumberofgrainlinesareverydifferentonthefrontascomparedtotheback.Radiallysawnplanksaregenerallymorestable.Whenapanelsupportiscomprisedofmultipleplanks,theorientationofthewoodgrainhasaneffectonthestabilityofthepanel.Ifthegrainofadjoiningplanksisorientedperpendiculartooneanother,structuralproblemscanarisewhenthesupportexperiencesenvironmentalfluctuations.Therefore,ifmultipleplanksaretobejoinedtogether,alloftheplanksshouldhavethewoodgrainorientedinthesamedirection.Supportscreatedfrommultipleplankscandevelopsplitsandcracksalongthejoinswhensubjectedtoadverseenvironmentalconditions,andtensionbetweenthesectionsofthewoodcanresultincrackingorsplitting.Artistswhoworkonalargerscaleshouldkeepthisinmindwhenselectingand/orpreparingwoodenpanelsupports.

Whenartistsusewoodensupports,theyshould: • Consideringusingwell-seasonedhardwoodslikemahogany,maple,or

oak.Inspectthesurfaceofthepaneltoensurethatnoknots,cracks,orotherdeformationsarepresent.

• Useplanksthatareatleast2.5cm(1”)thick,asthinnerboardsaremorelikelytosufferstructuraldeformation.

• Avoidsemi-hardwoodsandsoftwoodslikepoplarandpinewhenpossible.Ifthesewoodsarechosen,itisrecommendedthattheybecoveredwithalayerofcanvastopreventthetransferofsplitsandcracksfromthesupporttothegroundandpaintlayers.Largerformatwoodensupportscomprisedofmultipleplanksshouldalsobecoveredwithcanvas(overallifpossibleoratleastusecanvasstripstocoverjoins/splits)tohelppreventthetransferofsplitsandcracksfromthesupporttothegroundandpaintlayers.

• Considersizing(andpossiblypriming)bothsidesofthesupportinordertomitigatepotentialwarpinginthefuture.Thisprocedureensuresthatbothsidesofthepanelwillrespondmoresimilarlytoenvironmentalchanges.PossiblesizingmaterialstoconsiderincludeneutralpHPVA,certainacrylicpolymers(e.g.highqualityacrylicdispersionmediumsorgels),andvarnishcoatings(e.g.Regalrez1094,MSAvarnishes,etc.).Refinedshellacandpolyurethanecoatingshavealsobeenusedtoeffectivelyreducetheabsorbencyofthesurfaceandtosealthewoodbutartistsshouldtakecarenottoapplythesematerialstoothickly.Shellacandpolyurethanearelessthanidealmaterialsintermsofreversibility,brittlenessandagingcharacteristics.

• ConsiderapplyinganevencoatofneutralpHPVAadhesiveorcertainacrylicpolymers(e.g.highqualityacrylicdispersionmediumsorgels)

Page 4: MITRA Rigid Supports - UD ArtCons Supports.pdf · ARTISTS - Rigid Supports There are pros and cons to all ... Rigid supports made from hygroscopic materials like wood are ... including

whenadheringcanvas/papertothesurfaceofapanelfollowingdegreasing/cleaningofthesurface.Toadhereyourcanvastoapanel,thefollowingstepsarerecommended:

ApplyoneevencoatofPVAsizeoracrylicgelmediumtothesurfaceofthepanelusingaspatulaorabrush.Lightlywetthereverseofthecanvas(thesidethatwillbeadheredtothepanel)withwatertopromotebetteradhesion.Useabrayer/bonefoldertoeliminateanyairbubbles,workingfromthecenteroutwardstotheedges.Ifyouhavedecidedtokeepexcessfabricalongtheouteredges,foldthemoverandattachtothebacksideofthepanel(oraffixthemlater).ImmediatelyapplyanothercoatofPVAsizeoracrylicgelmedium(sticktothesamematerialyouusedpreviously)tothefaceofthecanvas.Oncethecanvashasdried,applyacoatofPVAsizeoracrylicgelmediumtothereverseofthepaneltopreventpotentialwarping.

• ConsiderusingBEVA371adhesive/filmtoadherecanvastopanelafter

thepanelhasbeensealed.BEVAfilm(asopposedtotheadhesive)willnotpenetratethefabricsupportasreadilyasPVAadhesiveand/oracrylicmediumsmightandtheabilitytore-activatetheadhesivemakesitfareasiertoeliminateanyunwantedair-bubbleslateronshouldtheyformduringtheprocess.Toadhereyourcanvastoapanel,thefollowingstepsarerecommended:

ApplyonetotwoevencoatsofdiluteBEVAadhesive(thincreamconsistency)tothepanelaftercleaningthesurfaceandtwocoatstothereverseofthecanvas(wearadequateprotectionassolventsarerequired).IfyouareusingBEVAfilmitisbettertousetwosheetsoffilmasopposedtoone,althoughonesheetmaybeabletoprovideenoughadhesion.PlacethefilmwiththeBEVA-sidefacingthepanel(orcanvasifyouareusingtwosheets)withoutremovingthesilicone-coatedMylarandapplyheatevenlyusinganiron(BEVAadhesiverequiresatemperatureofaround65.6degreesCelsiustobere-activated).WeightdownthesurfaceuntiltheBEVAhascooledandthencarefullypeelawaythesilicone-coatedMylar(NOTE:IfyouattempttoremovetheMylartoosoonyouwillpulluptheBEVA).Ifyouareusingtwosheets,repeatthisprocesswiththeothersheetofBEVAfilmwhenapplyingtothereverseofthecanvassupport(considerplacingsilicone-releasepaper/Mylarbeneaththecanvaswhenapplyingheat,siliconesidefacingup).ThenpositionyourcanvasdirectlyatoptheBEVAfilm,placesilicone-releasepaper/Mylar(siliconesidefacingdown)atopthecanvas,andapplyheat.IfyouareusingBEVAadhesivesimplywaitforthecoatsofBEVAtodry(inawellventilatedspace)andrepeattheaforementionedstep.IfyouexperiencedifficultiesusingBEVAfilm

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tryapplyingacoatofadhesivetothebackofthecanvasorswitchtotheadhesivealtogether.Considerusingatemperaturecontrolledvacuumtableifyouwishtoadhereacompletedpaintingontoapanel(ingeneralthisisnotrecommended).Itmaybepossibletosafelyadhereyourcompositionifitdoesnotcontainthicklybuiltuppaint,wax-basedadditives,orareasofstrongimpasto.Followtheinstructionsabovebutconsiderusingasoftblotterpaperoveryoursiliconereleasepaper/Mylartoprotectmoredelicatesurfaces(youmayalsoneedtoraisethetemperatureofyourironeversoslightly).

• Althoughrabbitskin/animalgluepossesseshygroscopicproperties,manyartistscontinuetousethistraditionalmaterialasasizeand/oradhesive.Toadhereyourcanvastoapanelusinganimalglue,thefollowingstepsarerecommended:

Prepareyouranimalgluefollowingthedirectionsonthepackage.Brushagenerous,evencoatofglueontothepanel’ssurface.Youmayallowthiscoattodrybeforecontinuingwiththeprocessorproceedimmediately.Wearingnitrilegloves,immersethecanvasintothetepidglue(makesurethatitisnotsohotastoburnyourhands),gentlywringthefabrictoremoveexcessglue.Positionthefabricontothepanel.Useabrayer/bonefoldertoeliminateanyairbubbles,workingfromthecenteroutwardstotheedges.Ifyouhavedecidedtokeepexcessfabricalongtheouteredges,foldthemoverandattachtothebacksideofthepanel(oraffixthemlater).Immediatelyapplyacoatofgluetothereverseofthepanel(NOTE:Itisnotadvisedtoleaveacoatofanimalglueexposedtotheenvironment.Subsequentlayersofprimingandpaintneedtobeappliedtothereverseinordertoavoidwarping,mimickingthesamelayeringusedonthefrontofthepanel).Allowforadequateandevendryingbystandingthepanelonitsedgeorleaningagainstawall.

• Provideadditionalauxiliarysupporttolargeformatpanelsandpanelsthatarelessthan¾”thickbyattachingabraceorcradlebygluingstripsofwoodaroundtheoutsideedgeofthebackofthepanelusingthefollowingsteps:

Obtain1”by2”woodenboards(oakormaplearepreferred)andcutthemdowntomatchtheouterdimensionsofthesupport(overallsizewilldependonwhattypeofjoinisusedforthecorners).Buttandmiteredtendtobethemostcommontypeofjoins(considerusinga90degree-cornerclampwhenmakingmiteredcorners),howeverlapjoinsaregenerallyconsideredtobemorestructurallysound.Makesurethatthewoodenboardsare

Page 6: MITRA Rigid Supports - UD ArtCons Supports.pdf · ARTISTS - Rigid Supports There are pros and cons to all ... Rigid supports made from hygroscopic materials like wood are ... including

perfectlyalignedandflushwiththeouteredgesbylayingthemonthereverseofthepanelbeforegluingtothereverse(itcanhelpfultomarkthepositionwithapencil).Usecarpenter’sgluetoadherethewoodenboardsinplaceWhiletheglueisdrying,clamp/weighttheboardstoavoidcreatinganyairbubbles.Forlarge-scalesupportsartistsmaychoosetoconstructhorizontaland/orverticalcrossbarsalthoughcrossbarsshouldNOTbeglueddirectlytothereverseofthepanel,onlyfixedtotheouterboardsofthecradleusingglueand/orhardware.

Plywood

Plywoodisalaminatedwoodproductthatispreparedbyadheringtogetherlayersofthinwoodveneer(plies)withthegrainofeachlayerpositionedatrightanglestothegrainoftheprecedinglayer.Sometypesofplywoodareavailablewithalumber,orsolidwood,core.

Diagram showing the alternating directional grain of a 5-ply, wooden

support. Some types of plywood are also available with a solid wood core.

Thecross-laminatestructureofplywood--particularlyifthepliesareallof

equalthickness--helpsensurethatthesupportislesspronetoplanardeformation.Plywoodcanbemadefromavarietyofsoftandhardwoods.Thelattertendstobemoredimensionallystable.Ingeneral,themorelayers,themoredimensionally

Page 7: MITRA Rigid Supports - UD ArtCons Supports.pdf · ARTISTS - Rigid Supports There are pros and cons to all ... Rigid supports made from hygroscopic materials like wood are ... including

stabletheplywoodsupport.Exterior-gradeplywoodhassuperiorresistancetomoisture,whileinterior-gradeplywoodhasthesmoothestsurfacefinish.

GatorfoamboardorGatorboardisnotplywood.itiscomposedofextrudedpolystyrenefoambondedbetweentwolayersofwood-fiberveneer.Itprovidesaveryrigidsurface,butthewood-fiberlayersmayrespondtochangesintheenvironment.

PlywoodandespeciallyGatorboardpanelsarenotconsideredsufficientlystableforpermanentuse.Artistsmaybeabletomitigatesomeoftheproblemsassociatedwiththesesubstratesbyconsideringthefollowingrecommendations:

• Inspectthesurfaceofplywoodtoensurethatarenoknots,cracks,or

otherdeformations.• Choosemaple,walnut,ormahoganyplywoodwhicharemoredurable

andstable(birchplywoodcanalsobeused,butthegrainhasatendencytotransferthroughtothegroundandpaintlayersovertime).

• Forlargerworkschooseplywoodthatisatleast¾”thickasthisexhibitsadequatedimensionalstability.

• PlywoodcanandGatorboardpanelsmaybenefitfromadheringafabriclayertothesurfacebeforepriming.Thesepanelsshouldbestoredflat.

• Considersizing(andpossiblypriming)bothsidesofthesupportinordertomitigatepotentialwarpinginthefuture.PossiblesizingmaterialstoconsiderincludeneutralpHPVA,certainacrylicpolymers(e.g.highqualityacrylicdispersionmediumsorgels),andvarnishcoatings(e.g.Regalrez1094,MSAvarnishes,etc.).Refinedshellacandpolyurethanecoatingshavealsobeenusedtoeffectivelyreducetheabsorbencyofthesurfaceandtosealthewoodbutartistsshouldtakecarenottoapplythesematerialstoothickly.Shellacandpolyurethanearelessthanidealmaterialsintermsofreversibility,brittlenessandagingcharacteristics.

• ConsiderapplyinganevencoatofneutralpHPVAadhesiveorcertainacrylicpolymers(e.g.highqualityacrylicdispersionmediumsorgels)whenadheringcanvas/papertothesurfaceofapanelfollowingdegreasing/cleaningofthesurface.Toadhereyourcanvastoapanel,thefollowingstepsarerecommended:

ApplyoneevencoatofPVAsizeoracrylicgelmediumtothesurfaceofthepanelusingaspatulaorabrush.Lightlywetthereverseofthecanvas(thesidethatwillbeadheredtothepanel)withwatertopromotebetteradhesion.Useabrayer/bonefoldertoeliminateanyairbubbles,workingfromthecenteroutwardstotheedges.Ifyouhavedecidedtokeepexcessfabricalongtheouteredges,foldthemoverandattachtothebacksideofthepanel(oraffixthemlater).ImmediatelyapplyanothercoatofPVAsizeoracrylicgelmedium(sticktothesamematerialyouusedpreviously)tothefaceofthecanvas.Oncethecanvashasdried,

Page 8: MITRA Rigid Supports - UD ArtCons Supports.pdf · ARTISTS - Rigid Supports There are pros and cons to all ... Rigid supports made from hygroscopic materials like wood are ... including

applyacoatofPVAsizeoracrylicgelmediumtothereverseofthepaneltopreventpotentialwarping.

• ConsiderusingBEVA371adhesive/filmtoadherecanvastopanelafterthepanelhasbeensealed.BEVAfilm(asopposedtotheadhesive)willnotpenetratethefabricsupportasreadilyasPVAadhesiveoracrylicmediumsmightandtheabilitytore-activatetheadhesivewithheatmakesitfareasiertolateraddressanyunwantedair-bubblesshouldtheyformduringtheprocedure.Toadhereyourcanvastoapanel,thefollowingstepsarerecommended:

ApplyonetotwoevencoatsofdiluteBEVAadhesive(thincreamconsistency)tothepanelaftercleaningthesurfaceandtwocoatstothereverseofthecanvas(wearadequateprotectionassolventsarerequired).IfyouareusingBEVAfilmitisbettertousetwosheetsoffilmasopposedtoone,althoughonesheetmaybeabletoprovideenoughadhesion.PlacethefilmwiththeBEVA-sidefacingthepanel(orcanvasifyouareusingtwosheets)withoutremovingthesilicone-coatedMylarandapplyheatevenlyusinganiron(BEVAadhesiverequiresatemperatureofaround65.6degreesCelsiustobere-activated).WeightdownthesurfaceuntiltheBEVAhascooledandthencarefullypeelawaythesilicone-coatedMylar(NOTE:IfyouattempttoremovetheMylartoosoonyouwillpulluptheBEVA).Ifyouareusingtwosheets,repeatthisprocesswiththeothersheetofBEVAfilmwhenapplyingtothereverseofthecanvassupport(considerplacingsilicone-releasepaper/Mylarbeneaththecanvaswhenapplyingheat,siliconesidefacingup).ThenpositionyourcanvasdirectlyatoptheBEVAfilm,placesilicone-releasepaper/Mylar(siliconesidefacingdown)atopthecanvas,andapplyheat.IfyouareusingBEVAadhesivesimplywaitforthecoatsofBEVAtodry(inawellventilatedspace)andrepeattheaforementionedstep.IfyouexperiencedifficultiesusingBEVAfilm,tryapplyingacoatofadhesivetothebackofthecanvasorswitchtotheadhesivealtogether.

Considerusingatemperaturecontrolledvacuumtableifyouwishtoadhereacompletedpaintingontoapanel(ingeneralthisisnotrecommended).Itmaybepossibletosafelyadhereyourcompositionifitdoesnotcontainthicklybuiltuppaint,wax-basedadditives,orareasofstrongimpasto.Followtheinstructionsabovebutconsiderusingasoftblotterpaperoveryoursiliconereleasepaper/Mylartoprotectmoredelicatesurfaces(youmayalsoneedtoraisethetemperatureofyourironeversoslightly).

• Althoughrabbitskin/animalgluepossesseshygroscopicproperties,

manyartistscontinuetousethistraditionalmaterialasasizeand/or

Page 9: MITRA Rigid Supports - UD ArtCons Supports.pdf · ARTISTS - Rigid Supports There are pros and cons to all ... Rigid supports made from hygroscopic materials like wood are ... including

adhesive.Toadhereyourcanvastoapanelusinganimalglue,thefollowingstepsarerecommended:

Prepareyouranimalgluefollowingthedirectionsonthepackage.Brushagenerous,evencoatofglueontothepanel’ssurface.Youmayallowthiscoattodrybeforecontinuingwiththeprocessorproceedimmediately.Wearingnitrilegloves,immersethecanvasintothetepidglue(makesurethatitisnotsohotastoburnyourhands),gentlywringthefabrictoremoveexcessglue.Positionthefabricontothepanel.Useabrayer/bonefoldertoeliminateanyairbubbles,workingfromthecenteroutwardstotheedges.Ifyouhavedecidedtokeepexcessfabricalongtheouteredges,foldthemoverandattachtothebacksideofthepanel(oraffixthemlater).Immediatelyapplyacoatofgluetothereverseofthepanel(NOTE:Itisnotadvisedtoleaveacoatofanimalglueexposedtotheenvironment.Subsequentlayersofprimingandpaintneedtobeappliedtothereverseinordertoavoidwarping,mimickingthesamelayeringusedonthefrontofthepanel).Allowforadequateandevendryingbystandingthepanelonitsedgeorleaningagainstawall.

• Provideadditionalauxiliarysupporttolargeformatpanelsandpanelsthatarelessthan¾”thickbyattachingabraceorcradlebygluingstripsofwoodaroundtheoutsideedgeofthebackofthepanelusingthefollowingsteps:

Obtain1”by2”woodenboards(oakormaplearepreferred)andcutthemdowntomatchtheouterdimensionsofthesupport(overallsizewilldependonwhattypeofjoinisusedforthecorners).Buttandmiteredtendtobethemostcommontypeofjoins(considerusinga90degree-cornerclampwhenmakingmiteredcorners),howeverlapjoinsaregenerallyconsideredtobemorestructurallysound.Makesurethatthewoodenboardsareperfectlyalignedandflushwiththeouteredgesbylayingthemonthereverseofthepanelbeforegluingtothereverse(itcanhelpfultomarkthepositionwithapencil).Usecarpenter’sgluetoadherethewoodenboardsinplaceWhiletheglueisdrying,clamp/weighttheboardstoavoidcreatinganyairbubbles.Forlarge-scalesupportsartistsmaychoosetoconstructhorizontaland/orverticalcrossbarsalthoughcrossbarsshouldNOTbeglueddirectlytothereverseofthepanel,onlyfixedtotheouterboardsofthecradleusingglueand/orhardware.

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Hardboards,Fiberboards,etc.

Theterms“hardboard”and“fiberboard”areoftenusedinterchangeablydespitethefactthattheyaredifferentproducts.ThemajordifferencebetweenhardboardssuchasfiberboardpanelslikeMediumDensityFiberboardandHighDensityFiberboard(e.g.Masonite)isthewayinwhichtheyaremanufactured.

Hardboardpanelsaregenerallycreatedthroughawet/dryprocesswhich

reliesonnaturallypresentcellulosiclignininthewoodtocementthefiberstogether.Temperedhardboardsareimpregnatedwithanoilyorresinoussubstancemakingthemdarkerincolor(untemperedhardboardsareusuallyalightbrowncolor)andmoreresistanttomoistureandmechanicaldamage(andthereforesubsequentwarping,raisingoffibers,etc.)thanuntemperedhardboard.Support-induceddiscoloration(SID)willoccuriftheoilyorresinousmaterialmigratesthroughthesizeorsealantandstainsthegroundand/orpaintlayers.Masonite,oneofthemostcommonlymanufacturedhardboards,firstbegantobeusedforartisticpurposesinthelate1920s

Fiberboardpanelsarecreatedthroughadryprocessthatreliesonchemicalagentslikeurea-formaldehydetobindthewoodfiberstogether.HighDensityFiberboard(HDF)issuperiortoMediumDensityFiberboard(MDF)asithassignificantlyhigherinternalbondstrengthandislesssusceptibletomoisturedamage.However,HDFisstillpronetoplanardeformation.Propersealingorsizingandgroundapplicationcanmitigatethisproblem.

Clayboardsarehigh-densityfiberboardsthathavebeencoatedwithalayerrichinclay(kaolin).Becausetheclaylayerservesasastableground,clayboardsarenotpronetosupport-induceddiscoloration(SID).AmpersandArtSupplyisamajordistributorofclayboards(andothersolidsupportsforartists).

Theadvantagesoftheseboardsoverwoodarethattheyareavailableinlargesheets,havenograin(i.e.,nodirectionalmovement),andarenotassensitivetoclimaticchangesorattackbywood-boringinsects.Largesheetsdotendtowarpandtwistandcornerscanbecomebent,compressed,orexpanded.Untemperedhardboardsshouldnotbeusediflong-termpreservationisaconcern.Untemperedhardboardwasoncepreferredovertemperedduetotheearlieruseofsubstantialamountsofoilincorporatedintotheearliertemperingformulationswhichcouldmaketheminappropriateasasurfacetoreceivewatercontaininggrounds.Highqualityhardboardspurchasedfromrespectedsuppliersdonotsufferfromthisdefect. Whenartistschoosetousethesesupports,theyshould:

• Degreasethesurfacewithdenaturedalcoholbeforeapplyinglayersofsize,ground,and/orpaint.Withoutthispreparation,groundlayersmaynotadheretothesmoothsideofthesesupportsbecauseofsurface

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residessuchasparaffinwaxthatmaybeleftduringthemanufacturingprocess.

• Gentlysandthefaceofthepanelwithfinesandpaper(e.g.220grit)toprovideaslightmechanicaltoothbutbecarefultonotoverlyroughenthesurfaceandunevenlyexposethewoodfibers.Thiscanleadtoirregularswellingofthesubstrate(particularlywhenwater-basedsizes,sealantsand/orpriming/groundareapplied).

• Considersizing(andpossiblypriming)bothsidesofthesupportinordertomitigatepotentialwarpinginthefuture.PossiblesizingmaterialstoconsiderincludeneutralpHPVA,certainacrylicpolymers(e.g.highqualityacrylicdispersionmediumsorgels),andvarnishcoatings(e.g.Regalrez1094,MSAvarnish,etc.).Refinedshellacandpolyurethanecoatingshavealsobeenusedtoeffectivelyreducetheabsorbencyofthesurfaceandtosealthewoodbutartistsshouldtakecarenottoapplythesematerialstoothickly.Shellacandpolyurethanearelessthanidealmaterialsintermsofreversibility,brittlenessandagingcharacteristics.

• ConsiderapplyinganevencoatofneutralpHPVAadhesiveorcertainacrylicpolymers(e.g.highqualityacrylicdispersionmediumsorgels)whenadheringcanvas/papertothesurfaceofapanelfollowingdegreasing/cleaningofthesurface.Toadhereyourcanvastoapanel,thefollowingstepsarerecommended:

ApplyoneevencoatofPVAsizeoracrylicgelmediumtothesurfaceofthepanelusingaspatulaorabrush.Lightlywetthereverseofthecanvas(thesidethatwillbeadheredtothepanel)withwatertopromotebetteradhesion.Useabrayer/bonefoldertoeliminateanyairbubbles,workingfromthecenteroutwardstotheedges.Ifyouhavedecidedtokeepexcessfabricalongtheouteredges,foldthemoverandattachtothebacksideofthepanel(oraffixthemlater).ImmediatelyapplyanothercoatofPVAsizeoracrylicgelmedium(sticktothesamematerialyouusedpreviously)tothefaceofthecanvas.Oncethecanvashasdried,applyacoatofPVAsizeoracrylicgelmediumtothereverseofthepaneltopreventpotentialwarping.

• ConsiderusingBEVA371adhesive/filmtoadherecanvastopanelafterthepanelhasbeensealed.BEVAfilm(asopposedtotheadhesive)willnotpenetratethefabricsupportasreadilyasPVAadhesiveoracrylicmediumsmightandtheabilitytore-activatetheadhesivewithheatmakesitfareasiertolateraddressanyunwantedair-bubblesshouldtheyformduringtheprocedure.Toadhereyourcanvastoapanel,thefollowingstepsarerecommended:

ApplyonetotwoevencoatsofdiluteBEVAadhesive(thincreamconsistency)tothepanelaftercleaningthesurfaceandtwocoatstothereverseofthecanvas(wearadequateprotectionassolvents

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arerequired).IfyouareusingBEVAfilmitisbettertousetwosheetsoffilmasopposedtoone,althoughonesheetmaybeabletoprovideenoughadhesion.PlacethefilmwiththeBEVA-sidefacingthepanel(orcanvasifyouareusingtwosheets)withoutremovingthesilicone-coatedMylarandapplyheatevenlyusinganiron(BEVAadhesiverequiresatemperatureofaround65.6degreesCelsiustobere-activated).WeightdownthesurfaceuntiltheBEVAhascooledandthencarefullypeelawaythesilicone-coatedMylar(NOTE:IfyouattempttoremovetheMylartoosoonyouwillpulluptheBEVA).Ifyouareusingtwosheets,repeatthisprocesswiththeothersheetofBEVAfilmwhenapplyingtothereverseofthecanvassupport(considerplacingsilicone-releasepaper/Mylarbeneaththecanvaswhenapplyingheat,siliconesidefacingup).ThenpositionyourcanvasdirectlyatoptheBEVAfilm,placesilicone-releasepaper/Mylar(siliconesidefacingdown)atopthecanvas,andapplyheat.IfyouareusingBEVAadhesivesimplywaitforthecoatsofBEVAtodry(inawellventilatedspace)andrepeattheaforementionedstep.IfyouexperiencedifficultiesusingBEVAfilm,tryapplyingacoatofadhesivetothebackofthecanvasorswitchtotheadhesivealtogether.Considerusingatemperaturecontrolledvacuumtableifyouwishtoadhereacompletedpaintingontoapanel(ingeneralthisisnotrecommended).Itmaybepossibletosafelyadhereyourcompositionifitdoesnotcontainthicklybuiltuppaint,wax-basedadditives,orareasofstrongimpasto.Followtheinstructionsabovebutconsiderusingasoftblotterpaperoveryoursiliconereleasepaper/Mylartoprotectmoredelicatesurfaces(youmayalsoneedtoraisethetemperatureofyourironeversoslightly).

• Althoughrabbitskin/animalgluepossesseshygroscopicproperties,

manyartistscontinuetousethistraditionalmaterialasasizeand/oradhesive.Toadhereyourcanvastoapanelusinganimalglue,thefollowingstepsarerecommended:

Prepareyouranimalgluefollowingthedirectionsonthepackage.Brushagenerous,evencoatofglueontothepanel’ssurface.Youmayallowthiscoattodrybeforecontinuingwiththeprocessorproceedimmediately.Wearingnitrilegloves,immersethecanvasintothetepidglue(makesurethatitisnotsohotastoburnyourhands),gentlywringthefabrictoremoveexcessglue.Positionthefabricontothepanel.Useabrayer/bonefoldertoeliminateanyairbubbles,workingfromthecenteroutwardstotheedges.Ifyouhavedecidedtokeepexcessfabricalongtheouteredges,foldthemoverandattachtothebacksideofthepanel(oraffixthemlater).Immediatelyapplyacoatofgluetothereverseofthepanel(NOTE:Itisnotadvisedtoleaveacoatofanimalglueexposedto

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theenvironment.Subsequentlayersofprimingandpaintneedtobeappliedtothereverseinordertoavoidwarping,mimickingthesamelayeringusedonthefrontofthepanel).Allowforadequateandevendryingbystandingthepanelonitsedgeorleaningagainstawall.

• Provideadditionalauxiliarysupporttolargeformatpanelsandpanels

thatarelessthan¾”thickbyattachingabraceorcradlebygluingstripsofwoodaroundtheoutsideedgeofthebackofthepanelusingthefollowingsteps:

Obtain1”by2”woodenboards(oakormaplearepreferred)andcutthemdowntomatchtheouterdimensionsofthesupport(overallsizewilldependonwhattypeofjoinisusedforthecorners).Buttandmiteredtendtobethemostcommontypeofjoins(considerusinga90degree-cornerclampwhenmakingmiteredcorners),howeverlapjoinsaregenerallyconsideredtobemorestructurallysound.Makesurethatthewoodenboardsareperfectlyalignedandflushwiththeouteredgesbylayingthemonthereverseofthepanelbeforegluingtothereverse(itcanhelpfultomarkthepositionwithapencil).Usecarpenter’sgluetoadherethewoodenboardsinplaceWhiletheglueisdrying,clamp/weighttheboardstoavoidcreatinganyairbubbles.Forlarge-scalesupportsartistsmaychoosetoconstructhorizontaland/orverticalcrossbarsalthoughcrossbarsshouldNOTbeglueddirectlytothereverseofthepanel,onlyfixedtotheouterboardsofthecradleusingglueand/orhardware.

LaminatedPaperBoardsandMuseumBoards

PaperboardsmadefromwoodwasteorwoodpulparesoldunderavarietyoftradenamesincludingUpsonBoardandBeaverBoard.Laminatedpaperboardsshouldbethoughtofastemporarysupports.Theyarehighlyacidicandhaveaweakphysicalstructure,sotheydeterioratequickly.Museumboardisahighqualitylaminatedpaperboardmadeof100%cottonragmatboard.Museumboardshavebetweentwoandeightdistinctlayers.Asmuseumboardlacksstructuralstrength,forincreasedrigidityitshouldbemountedonawoodenauxiliarybraceorpanel.CanvasBoards

Canvasboardsareconstructedfromathinlayerofcottonormuslinprimedwithanacrylicdispersiongroundthathasbeengluedtoasheetofpulpcardboard.Theseboardsshouldnotbeusediflong-termpreservationisaconcern.

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Aluminum

Aluminumpanels,AluminumCompositeMaterial(ACM)panels,aluminumhoneycombpanels,andDibondpanelshavebeenwidelyusedbyartistssincethelate1940s.Aluminumismoreresistanttocorrosionthanothermetals,canbecuteasilywithabandsaw,and,dependingonthesizeandthicknessofthepanel,willretainstiffness.Itisnecessarytonotethat,eveninastableenvironment,thinnerpiecesofaluminumwillnotremainplanar.

ACMboardsdifferbymanufacturerbutaretypicallycomposedofathermoplasticcoresandwichedbetweentwolightweightsheetsofaluminum.Theseboardscanbepurchasedwithtwosidesofexposedaluminumandnopreparatorylayer,withacanvasmountedtoonesideandamill(polishedaluminum)finishonthereverse,orwithonesidecoatedwithawhitepolyestercoilfinishtoprotectthesurfaceagainstcorrosion.

ArtefexACMPanelsarecomprisedoftwosheetsof3mmaluminumbondedtoasolidpolyethylenecore.Theycanbepurchasedwithorwithoutapreparatorylayerandwithorwithoutonesidecoveredwithcanvas.DibondACMPanelsaremadeoftwolightweightsheetsof.010”aluminumwithathermoplasticcore.Theyareavailableinavarietyofcolors.

TheadvantagesofACMpanelsoverwoodorstretchedcanvasarethattheydonotrespondasreadilytochangesinRHandarenotpronetoinsectdamage.

Diagram showing the typical layering structure of an Aluminum Honeycomb

Panel.

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Diagram showing an example of the layering structure of an Aluminum

Composite Panel (ACM).

Artistswhochoosetousethesesupportsshould:• Preparethealuminum/ACMsurfacesbyremovingtheprotectivefilm.

Degreasingthepresentationside(typicallythesidecoatedwithpolyester)withethanolorisopropanol.Createatooth(e.g.100/200gritsandpaper)bylightlyrougheningthesurfacewithanabrasivematerialNOTE:Ifawhiteprotectivepolyestercoilcoatingispresentavoidbreakingcompletelythroughitasthisexposestheunderlyingaluminumandcanleadtocorrosion.

• AvoidACMpanelsthatdonothaveapolyestercoilcoating(inindustryACMpanelscanbecoatedwitharangeofmaterials).

• Chooseapriming/groundmaterialcarefully.Priming/groundmaterialsthatareavailableinindustrymaybeacceptableiftheyhavebeenfoundtobecompatiblewithcertainACMbrands(Example:DTMBondingPrimerbySherwinWilliamshasbeenfoundtobehighlycompatiblewithDibondpanels).Aswithmostindustryproducts,artistsareencouragedtotestthesematerialswiththeirpreferredpaintingtechnique.

• FixthinnersupportstomorerigidsupportssuchasMasoniteorconstructacradle(seeinstructionsbelow).Sheetsthataretoothinaremorepronetodamageastheymayflexandtwistduringtransportationandhandling.

• Rememberthat“fatoverlean”principlesshouldbefollowedwhenapplyingalkyd,acrylics,and/oroilpaints.

• UnderstandthatACMpanelswithhoneycomborcorrugatedplasticcores(suchasArtefex)tendtobelighterinweightthanACMpanelsthatcontainsolidplasticcores.

• Avoidsubjectingthepaneltoextremelyhightemperatures(above175F). • Knowthatsupportsthatarefairlyheavyareatriskofplanardeformation

alongtheouteredges(e.g.bentcorners)especiallyduringtransportationandhandling.

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• Avoidpaintingdirectlyonthesurfaceofunprimedaluminumasthistechniquecanleadtoadhesionproblems.

• ConsiderapplyinganevencoatofneutralpHPVAadhesiveorcertainacrylicpolymers(e.g.highqualityacrylicdispersionmediumsorgels)whenadheringcanvas/papertothesurfaceofapanelfollowingdegreasing/cleaningofthesurface.Toadhereyourcanvastoapanel,thefollowingstepsarerecommended:

ApplyoneevencoatofPVAsizeoracrylicgelmediumtothesurfaceofthepanelusingaspatulaorabrush.Lightlywetthereverseofthecanvas(thesidethatwillbeadheredtothepanel)withwatertopromotebetteradhesion.Useabrayer/bonefoldertoeliminateanyairbubbles,workingfromthecenteroutwardstotheedges.Ifyouhavedecidedtokeepexcessfabricalongtheouteredges,foldthemoverandattachtothebacksideofthepanel(oraffixthemlater).ImmediatelyapplyanothercoatofPVAsizeoracrylicgelmedium(sticktothesamematerialyouusedpreviously)tothefaceofthecanvas.Oncethecanvashasdried,applyacoatofPVAsizeoracrylicgelmediumtothereverseofthepaneltopreventpotentialwarping.

• ConsiderusingBEVA371adhesive/filmtoadherecanvastopanelafterthepanelhasbeensealed.BEVAfilm(asopposedtotheadhesive)willnotpenetratethefabricsupportasreadilyasPVAadhesiveoracrylicmediumsmightandtheabilitytore-activatetheadhesivewithheatmakesitfareasiertolateraddressanyunwantedair-bubblesshouldtheyformduringtheprocedure.Toadhereyourcanvastoapanel,thefollowingstepsarerecommended:

ApplyonetotwoevencoatsofdiluteBEVAadhesive(thincreamconsistency)tothepanelaftercleaningthesurfaceandtwocoatstothereverseofthecanvas(wearadequateprotectionassolventsarerequired).IfyouareusingBEVAfilmitisbettertousetwosheetsoffilmasopposedtoone,althoughonesheetmaybeabletoprovideenoughadhesion.PlacethefilmwiththeBEVA-sidefacingthepanel(orcanvasifyouareusingtwosheets)withoutremovingthesilicone-coatedMylarandapplyheatevenlyusinganiron(BEVAadhesiverequiresatemperatureofaround65.6degreesCelsiustobere-activated).WeightdownthesurfaceuntiltheBEVAhascooledandthencarefullypeelawaythesilicone-coatedMylar(NOTE:IfyouattempttoremovetheMylartoosoonyouwillpulluptheBEVA).Ifyouareusingtwosheets,repeatthisprocesswiththeothersheetofBEVAfilmwhenapplyingtothereverseofthecanvassupport(considerplacingsilicone-releasepaper/Mylarbeneaththecanvaswhenapplyingheat,siliconesidefacingup).ThenpositionyourcanvasdirectlyatoptheBEVAfilm,

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placesilicone-releasepaper/Mylar(siliconesidefacingdown)atopthecanvas,andapplyheat.IfyouareusingBEVAadhesivesimplywaitforthecoatsofBEVAtodry(inawellventilatedspace)andrepeattheaforementionedstep.IfyouexperiencedifficultiesusingBEVAfilm,tryapplyingacoatofadhesivetothebackofthecanvasorswitchtotheadhesivealtogether.Considerusingatemperaturecontrolledvacuumtableifyouwishtoadhereacompletedpaintingontoapanel(ingeneralthisisnotrecommended).Itmaybepossibletosafelyadhereyourcompositionifitdoesnotcontainthicklybuiltuppaint,wax-basedadditives,orareasofstrongimpasto.Followtheinstructionsabovebutconsiderusingasoftblotterpaperoveryoursiliconereleasepaper/Mylartoprotectmoredelicatesurfaces(youmayalsoneedtoraisethetemperatureofyourironeversoslightly).

• Provideadditionalauxiliarysupporttolargeformatpanelsandpanels

thatarelessthan¾”thickbyattachingabraceorcradlebygluingstripsofwoodaroundtheoutsideedgeofthebackofthepanelusingthefollowingsteps:

Obtain1”by2”woodenboards(oakormaplearepreferred)andcutthemdowntomatchtheouterdimensionsofthesupport(overallsizewilldependonwhattypeofjoinisusedforthecorners).Buttandmiteredtendtobethemostcommontypeofjoins(considerusinga90degree-cornerclampwhenmakingmiteredcorners),howeverlapjoinsaregenerallyconsideredtobemorestructurallysound.Makesurethatthewoodenboardsareperfectlyalignedandflushwiththeouteredgesbylayingthemonthereverseofthepanelbeforegluingtothereverse(itcanhelpfultomarkthepositionwithapencil).Useanappropriateadhesive(pleaserefertotheDibondManuallocatedinourreferencesection)toadherethewoodenboardsinplacewhiletheglueisdrying,clamp/weighttheboardstoavoidcreatinganyairbubbles.Forlarge-scalesupportsartistsmaychoosetoconstructhorizontaland/orverticalcrossbarsalthoughcrossbarsshouldNOTbeglueddirectlytothereverseofthepanel,onlyfixedtotheouterboardsofthecradleusingglueand/orhardware.

Copper

Artistshaveusedcoppersupportssincethe17thcenturyforbothpracticalandaestheticreasons.Copperpanelsaredurableandcompactandareavailableinarangeofportablesizesbutaremorepronetocorrosionthanaluminum.Acoppersupporttendstogiveawarmtonetotheoverallcompositionasoilpaintsdonot

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sinkintothegroundastheydooncanvasorwoodenpanelssotheycanremainintenselysaturatedevenwhenappliedinthinlayers.Artistswhochoosetousecoppersupportsshould:

•Preparethesurfacebydegreasingthepresentationsidewithsolvents(e.g.mineralspiritsfollowedbydenaturedalcohol)andcreatingatoothbyrougheningthesurfacewithanabrasivematerial.NOTE:Thereisnoneedtopurchasecostlier“polished”copperetchingplatesasartistsareencouragedtoabradethesurfaceanyhowtoimproveadhesion.

• Sheetsthataretoothinaremorepronetodamageastheycanflexandtwistduringtransportationandhandling.Selectcopperpanelsthatareofanappropriatethickness(e.g.highqualitycopperetchingplates).

•Fix/adherethinnersupportstomorerigidsupportssuchasMasonitebygloballyapplyinganadhesivelikeepoxyinanevenmannertothesheetand/ortherigidsupport(abradethereverseofthepanelpriortogluingtoimproveadhesion).Ingeneral,however,thingaugecopperpanelsshouldbeavoided.

•Rememberthat“fatoverlean”principlesshouldbefollowedwhenapplyingalkyd,acrylics,and/oroilpaints.

•Avoidaqueous-basedground/paintmaterialsinordertopreventtheformationofcorrosionproducts.

•Notpaintdirectlyonthesurfaceofunprimedcopperasthistechniquemayleadtopotentialadhesionproblemsinthefuture.

OtherMetalSupports

Tin,tin-platediron,steel,zinc,andothermetalshaveoccasionallybeenusedbyartistsassupports.Tin-containingsupportsaresusceptibletocorrosionwhenexposedtohighhumidity,oxygen,andatmosphericpollutants.Zincsupportsarelesspronetocorrosioninhumidenvironmentsthancoppersupports,buttheyaremoresusceptibletodegradationwhenexposedtoacidicoralkalinematerialsandconditions.Athintransparentfilmofzincoxide(whichappearsasabluish-whitefilm)canformonazincpanelwhenitisexposedtoair.Thezincoxidethencanreactwithfattyacidsinoilandalkydpaintstoformzincsoaps(whichmayprotrudethroughthesurfaceasunsightlypustules).Steelandstainlesssteelarenotcommonlyusedassupportsduetotheweightofthesemetalalloys.Steeliscomposedofironandcarbonwithsmalleradditionsofothermetallicelementssuchasmolybdenum,manganese,copper,chromium,ornickel.Thelargerpercentageofchromiuminstainlesssteel(aminimumof10.5%bymass)iswhatgivesitcorrosionresistance.

Slate/Stone/Marble/Porphyry

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Itislikelythatvariousstoneshavebeenusedaspaintingsubstratessinceantiquity.Stonesormarblesthathaveafinegrain(arenotporous)andcanbeevenlypolishedarethemostsuitableforuseaspaintingsupports.Stonesupportsaremechanicallystableastheydonotchangewithhumidityfluctuationsandareimpervioustowormsandinsects.Brittleness,poorpreparationofthesurface,andpoorapplicationofthepaintandgroundlayers(e.g.deviatingfromthefatoverleanprinciple)cancausedelamination.Glass

Glasssupportssharethemechanicalstabilityandinsectresistanceofstonesupports,butpossessahighlyfinished,non-poroussurface.However,glassisinherentlyfragileandpronetobreakage(particularlyaroundtheouteredges)andcanbecomemorebrittleasitsages.Aspaintandgroundlayerscanreadilydelaminateduetotheslicksurface,glasssupportsarenotrecommended.Ifartistschoosetouseglasssupports,onlyfrostedorsandblastedglassshouldbeusedandthesurfaceshouldbedegreasedwithethanoloracetonebeforeuse. Polyvinylchloride(e.g.Sintra)

Themainissuewiththeuseofpolyvinylchloride-basedplasticsaspaintingsupportsisthepresenceofplasticizersandotheradditiveswhichareaddedduringthemanufacturingprocess.Withouttesting,itisdifficulttoidentifythespecificpolymerblendspresentwithinapolyvinylchloride(PVC)sheetortoknowhowstablethematerialis.Overtime,theplasticizersinaPVCsheetcanmigratetothesurfaceformingvisibleliquiddropswhichbecometackyandthencrystalline.Themigrationofplasticizerswilllikelycausedelaminationofthepaintand/orgroundlayers.SheetsofPVCcanwarpandwillsometimesgrowmoldwhenexposedtohighlevelsofhumidityandheat.Polyvinylchlorideisnotrecommendedasapermanentsupportforworksofart.

IftheartistinsistsonusingaPVCsupport,thebestprocedureistopaintonaproperlyprimedcanvasandadherethefinishedcanvastotheplasticsheet.Thisway,iftheplasticsupportdeteriorates,thecanvascanberemovedandadheredtonewsupport. Polycarbonate(e.g.Lexan)

Likepolyvinylchloride-basedplastics,polycarbonatesalsotendtocontainawiderangeofadditivesthatcanposepotentialproblemsforartists.Polycarbonatesarelong-chainlinearpolyestersofcarbonicacidanddihydricphenols(e.g.BisphenolA).Thereareseveralgradesofpolycarbonatesheetingavailabletodayanddistinguishingonefromanotherreallydependsontheadditivespresentwhichcanincludeglassfibers,UVstabilizers,moldreleaseagents,andflameretarders.Thepresence/absenceofthesestabilizerswillinturnaffectthepolycarbonate’sresistancetoheat,itsbrittleness,anditstendencytodegradeinUVlight.

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Polycarbonatecanalsobeincrediblysensitivetocertainsolvents;artistsshouldavoidbringingacetone,aromatics,andothersolventstosurfaceofPlexiglass,stickinginsteadtowaterormineralspirits-basedproducts.

Theprimaryconcernregardingtheseadditivesistheirtendencytomigrateoutofthesubstrateslowlyovertime(orquicklydependingonthenatureoftheenvironment).Forexample,themigrationofBisphenol-Ainclearpolycarbonateplastics(e.g.waterbottles)hasbeenextensivelystudied,aphenomenonthatcouldverylikelycausedelaminationand/orflakingoftheoverlyingground/paintlayers.Itisforthisreasonthatpolycarbonatesupportsarenotrecommendedforartworksthatareintendedtolast.PolymethylMethacrylate(e.g.Plexiglas)

Plexiglassisoneofseveraltrademarkednamesusedtomarketclearsheetsofpolymethylmethacrylate,amaterialthatisapopularsupportamongartists.Thesesheetstendnottocontainpotentiallyproblematicadditivessuchasthosefoundinpolyvinylchloride-andpolycarbonate-basedmaterials.However,Plexiglasswillexpandandcontractinresponsetochangesintemperatureandhumidity,leadingtoeventualwarpingorbendingofthesupport.Thiscanbeproblematicifverybrittlematerialsareusedinthepaintand/orgroundlayers(e.g.oils,alkyds,certainresins)asdelaminationandcrackingmayoccurasthesupportexpandsandcontracts.Watercolors,tempera,andmostgouachepaintsshouldbeavoided.Theglassy-likesurfaceofPlexiglassmakesforasurfacethatcanbeeasilyscratchedandcanbuildupastaticchargethatcanattractdustparticles.PlexiglassispronetoyellowingifexposedtoUVlightandcanbeextremelysensitivetocertainsolvents;artistsshouldavoidbringingacetone,aromatics,andothersolventstosurfaceofPlexiglas,stickinginsteadtowaterormineralspirits-basedproducts.Finally,andperhapsmostimportantly,Plexiglasssupportsareinherentlybrittleandeasilyshatterorcrackifdroppedordamaged.

Ifanartistinsistsonusingapolymethylmethacrylatesupport,thebestprocedureistoinitiallysandthesurfaceinordertoprovidesomemechanicaltoothtoimprovetheadhesionofthepaintandgroundlayers.ArtistsshouldconsiderpaintingandprimingwithacrylicsifusingPlexiglassastheydoretainsomedegreeofflexibility.AvoidinstallinginflexiblehardwaredirectlyintothePlexiglass,choosethickerratherthanthinnersheets,anduseachanneledframetohouse/displaythePlexiglass. ADDITIONALREFERENCESANDRESOURCESGeneral“”Supports”inThePainter'sHandbook:RevisedandExpandedbyMarkDavidGottsegen(NewYork:Watson-Guptill,2006).

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“HistoryandUseofPanelsorOtherRigidSupports”byJorgenWadumandNoelleStreetoninTheConservationofEaselPaintings,eds.Dr.JoyceHillStonerandRebeccaRushfield(LondonandNewYork:Routledge,2012).GoldenArtistColors-PreparingaPaintingSupporthttp://www.goldenpaints.com/technicalinfo_prepsuppCAMEO:ConservationandArtMaterialsEncyclopediaOnline(MuseumofFineArtsBoston)http://cameo.mfa.org/wiki/Main_PageWoodKressTechnicalArtHistoryWebsite-WoodenSupportshttps://www.artcons.udel.edu/about-us/kress/historical-materials-techniques/wooden-supports GoldenArtistsColors-UnderstandingWoodSupportsforArt-ABriefHistorybyElaineSalazarhttp://oldsite.goldenpaints.com/justpaint/jp29article3.php Britannica–WoodSciencehttp://www.britannica.com/science/wood-plant-tissue TransportInformationServices–PropertiesofVariousWoodSpecieshttp://www.tis-gdv.de/tis_e/misc/holzart.htmTheEncyclopediaofWood,U.S.DepartmentofAgriculture,2007[portionsavailable]https://books.google.com/books?id=qxQnAgAAQBAJ&pg=PT354&lpg=PT354&dq=%E2%80%A2+The+Encyclopedia+of+Wood,+USDA&source=bl&ots=MYUmCSV66b&sig=xUESVua9_cPCeLrPxf08t7N_2fQ&hl=en&sa=X&ved=0ahUKEwjard7PxZnOAhUCNSYKHbvzBaMQ6AEIcjAJ#v=onepage&q=%E2%80%A2%20The%20Encyclopedia%20of%20Wood%2C%20USDA&f=false]

Hardboard,Fiberboard,etc.JournaloftheAmericanInstituteforConservation(JAIC)-“Shortcommunicationearlywood-fiberpanels:Masonite,hardboard,andlower-densityboards”byAlexanderW.Katlanhttp://cool.conservation-us.org/jaic/articles/jaic33-03-005.htmlGoldenArtistsColors-PlywoodasaSubstrateforPaintinghttp://oldsite.goldenpaints.com/justpaint/jp29article4.phpAmpersand-PaintingPanelsforArtistshttp://www.ampersandart.com/products_main.htmlAmericanHarboatdAssociation-Today’sHardboard

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http://domensino.com/aha/images/tdyhdbrd.pdfCompositePanelAssociationhttp://www.compositepanel.org/CompositePanelAssociation-MDFFromStarttoFinishhttp://www.hardwoods-inc.com/sites/default/files/mdf_start_to_finish_2005.pdf“Wood-basedCompositesandPanelProducts”byJohnA.YoungquistinForestProductsLaboratory*Madison,WI:I.S.DepartmentofAgriculture,1999)http://www.carbeck.org/pdfs/FPL_Wood_Handbook_Ch10.pdfPanelProcessing,Inc.–“Hardboard(Masonite)Whatisit?”byRMGranumandO.B.Eustishttps://harborsales.net/Portals/0/docs/hardboard_what_is_it.pdfAluminumDibondFabricationManualhttp://graphicdisplayusa.com/downloads/Dibond%20Fabrication%20Manual_May%202011.pdfGraphicDisplay,USA-Dibondhttp://graphicdisplayusa.com/products/dibond/NaturalPigments-ArtefexACMpanelshttp://www.naturalpigments.com/custom-artefex-panel.htmlJackson’s-AluminumPaintingPanelshttps://www.jacksonsart.com/blog/2014/03/28/aluminium-painting-panels/SOSGraphics–SubstrateListhttp://www.sosgraphics.ca/SOSMaterialList.pdfCopperCopperasCanvas:TwoCenturiesofMasterpiecePaintingsonCopper,1575–1775,ed.byMichaelK.Komanecky(Oxford:OxfordUniversityPress,1998).Plastics,etc.GoldenArtistColors–AcrylicsonPlasticshttp://www.justpaint.org/acrylics-on-plasticsSOSGraphicsSubstrateListhttp://www.sosgraphics.ca/SOSMaterialList.pdfPolycarbonatesandotherplasticshttp://www.ptsllc.com/intro/polycarb_intro.aspx

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Plexiglashttp://www.plexiglas.com/export/sites/plexiglas/.content/medias/downloads/sheet-docs/plexiglas-general-information-and-physical-properties.pdfPlasticsinArt:AStudyfromtheConservationPointofView,byFriederikeWaentig(Petersberg:Imhof.,2008).PlasticsinArt:History,Technology,Preservation,byTheavanOosten,YvonneShashoua,andFriederikeWaentig(Munich:Siegl,2002).