MATERIALS INFORMATION and TECHNICAL RESOURCES for

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MATERIALS INFORMATION and TECHNICAL RESOURCES for
MATERIALSINFORMATIONandTECHNICALRESOURCESfor
ARTISTS
SurfaceCoatings,RetouchingVarnishes,andOilingOut
VARNISHESUSEDASFINALSURFACECOATINGS
Syntheticandnaturalvarnishesaregenerallyappliedtothesurfaceofan
artworktoaddalayerofprotection.Manyvarnishesalsoimpartsaturation,giving
moredepthtodarkerpassagesandimprovecontrast.Thechoiceofwhattypeof
varnishcoatingtousecanhaveasignificantimpactonboththeimmediate
appearanceoftheartworkandalsohowanartworkwilllookintheyearstocome.
Somevarnishesaremoresusceptibletoyellowingand/ordarkeningwhileothers
canturncloudyorhazyovertime.Finally,ahandfulofmaterialsthataremarketed
assurfacecoatingsshouldneverbeusedasvarnishesforfineart,assomeofthese
proprietarymaterialsandindustrialcoatingsbecomeirreversibleandinsolubleas
theyage.Todayartistshaveattheirdisposalawiderangeofvarnishestochoose
from,someofwhichhavebeenextensivelytestedtoevaluatespecificaging
properties(includingeaseofremovability,propensityforyellowing/darkening,and
glasstransitiontemperatureasitrelatestotackiness).Itisimportanttoremember
thatevenifthesourceofavarnishis“natural”(e.g.isharvestedfromthesapofa
tree)thisdoesnotnecessarilymeanthatitisasuperiorproductthatwillwithstand
thetestoftime.
Majorquestionstoconsiderwhenselectingavarnishforyourartworkincludethe
following:
• Willthevarnishdiscolor,bloom,and/ordarkenovertime?
• Willitbepossibletosafelyremovethevarnishfromtheartworkshouldthe
needarise?
IdealPropertiesofaFinalSurfaceCoating
Materialsthatareconsideredsuitableforvarnishingshould:
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Beflexibleenoughtowithstandtheexpansionandcontractionthatthe
artworkundergoesinresponsetoatmosphericchanges(thisisparticularly
importantifpaintingisexecutedonaflexiblesupport).Varnishesthatare
toobrittlearepronetocrackingandevendelamination.
Maintainadesirableleveloftransparency.
Remaincolorless
Remaineasilyremovableevenafteraging.
Createafilmthatisfairlyfastdryingsoastoavoidremainingtackyand
accumulatingdustandgrime.
Possessdesirableworkableproperties;varnishesshouldbeabletobespread
thinlyinsuccessivecoatsand/orbeappliedusingaspraygun.Notethat
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thinnercoatingsaregenerallylighterinhueandlesslikelytocrackasthe
underlyingsubstrateexpandsandcontractswhilethickercoatingsaremore
likelytodiscolorataquicker,morenoticeablerateandmaybebrittle.
Fulfillitsfunctionisathinfilmsothatitdoesnotfillinanytexturaleffectson
thesurfaceofthepainting.
Thevarnishresinmustbedissolvedinasolventthatwillnotdisturbor
dissolvethepaintduringitsapplication.
Createaproperordesirablelevelofgloss,saturation,andsurfacefinish.
Notbesusceptibleto“bloom,”aphenomenonthatresultsfromthe
gradual/immediatepenetrationofwatervaporthatcreatesacloudy,hazy
appearance.
DisadvantagesandAdvantagestoVarnishing
Advantages
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Varnishingcanprovidealayerofprotectionforyourartworkfromthe
accumulationofdirt/grime,potentialscratchesandscuffstothepaintlayer,
andcanevenhelptoprevent/slowthefadingoflight-sensitivepigments
UVlightstabilizers(UVLS)canbeeasilyaddedtovarnishesandareeven
presentinsomepre-madevarnishes.Thesecanimproveavarnishes
resistancetolightdeteriorationandlengthentheserviceabilityofthe
coating.IfUVLSsarepresentinavarnishsolution,thesolutionshouldbe
keptinanamberjarand/orkeptoutofthelight.WhenUVLSsareaddedtoa
varnishmixture,itisbesttousethevarnishinatimelyfashion(prepare
smallquantitiesandusewithinamonthorso).
Althoughthereisadividedopiniononwhetherornotitisconsideredbest
practicetovarnishacrylicpaintings,artistsshouldnotethatacrylicfilmsare
usuallymoreporousthanoil/alkydfilmsandcansufferfromthe
accumulationofdirtandgrimeovertime.
Varnishescanbemodifiedtoprovideawiderangeoffinishes,frommatteto
satintoglossy.Manyartistsfeelthatvarnishingimprovestheoverall
saturationandoriginalcontrastoftheircompositions,reestablishingthe
separationofthelighterareasandtherichnessofthedarkerpassages.
Iftheappropriatevarnishhasbeenusedandthesurfaceoftheartwork
becomesdamaged,aproperlyformulatedvarnishshouldbeeasilyremoved
withoutcompromisingthepaintlayer(s).Artistsarenotadvisedtouse
ammonia-basedsolutionsbutinsteadtousesimplemineralspiritstoremove
fairlyyoungvarnishcoatings.Ifyouencounterdifficultiesinremovingyour
varnish,pleasecontactaprofessionallytrainedconservatorwithagraduate
degreeinArtConservation.
Disadvantages
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Varnishingrequiresanadditionalsteponcetheartworkhasbeencompleted,
sometimesafterithasbeenacquiredbyacollector.
Foroilandalkydpaintings,onemusttypicallywait6monthstoayearin
ordertoensurethatthevarnishdoesnot“sinkin”andbecomeincorporated
intotheslow-curingoilfilm.
Theapplicationofvarnishescansometimesbechallenging.Bubblescan
form,reticulation(beadingup)canoccur,andstreakscanappear(see
“ApplicationProcesses”attheendofthisdocumentsfortipsonhowtoavoid
theseproblems).
Ifanirremovablevarnishmaterialisusedthenitisnearlyimpossibletolater
addressscratches,bloom,stains,andothertypesofdamagethatmayoccur.
Allvarnisheswillalterthelevelofsaturationinapainting,anaesthetic
changethatmayormaynotbedesirabletotheartist.Itisalwaysagoodidea
totestyourselectedvarnishonmock-uppaintingsorsketchesbefore
applyingthemtofinishedworks.
Manyproprietaryacrylic-basedvarnishesaremarketedtodayassuitablefor
useonalkyd,oil,andacrylicpaintings.However,manystillawaitfurther
testingtoevaluatewhethertheydoinfactdegradeand/orwhethertheycan
besafelyremovedfromartworksovertime.Artistsareadvisedtocarefully
considerthesefactorswhenselectingavarnish.
CATEGORIESOFVARNISHES/SURFACECOATINGS
Historic/Traditional
Oil-ResinVarnishes–Oil-resinorcooked-oilvarnishesaresolutionsofresins
dissolvedinheatedoils(e.g.amber-oil,copal-oil).Sometimesthesevarnisheswere
preparedinthepresenceofdriers(e.g.litharge)tohelpquickenthedryingtimeof
thesematerials.Whilecooked-oilvarnishescreatemuchtougherfilmsthanother
typesofvarnishes,theya)becomeimpossibletoremoveovertimeb)willyellow
anddarken,andc)canbecomebrittlewithage.Artistsshouldneverusetheseas
surfacecoatings.
Water-basedVarnishesandCoatings-Water-basedvarnishesandcoatingsare
materialsdissolvedinwaterthatwereoccasionallyusedasfinalandeven
temporaryvarnishes.Examplesincludeeggwhite(glair),water-solublegums(gum
Arabic,cherrygum),andanimalglues.Noneofthesecoatingspossessgoodlongtermagingpropertiesandcanformfilmsthateventuallybecome
insoluble/irremovablegrey,hazycrusts.
ModernMaterials
Lacquers,Alkyds,Polyurethanes,andEnamels–Todaythereisawide-rangeof
lacquer-,alkyd-(e.g.Liquin),polyurethane-,andenamel-basedcoatingsavailableto
artists,someofwhichconsistentofnitrocellulose(andothercellulosederivatives)
orvinyl-based/acrylicresinsdissolvedinsolvents.Whilemanyoftheseproducts
dryfairlyquickly,theyarenotrecommendedforuseassurfacecoatingsastheyare
irremovableoncedry,mayproducebrittlesurfacecoatings,andwithgenerally
yellowanddarkenovertime.Thesetypesofproductshaveexperiencedarisein
popularityamongcontemporaryartistsandwhiletheymaycreateaesthetically
pleasingsurfacesforsome,theiruseonfineartishighlyproblematic.
NOTE:Liquinandotheralkydoilmediumsshouldneverbeusedasasurface
coatingasitisdesignedtofunctionasapaintmediumratherthanavarnish.Alkyd
mediums,likeallmaterialscontainingdryingoils,willyellowovertime.Theyare
alsonotreversibleandwillbecomeimpossibletosafelyremovefromthesurfaceof
anartworkasitages.Thisisparticularlydisastrousiftheartworkbecomes
damagedandinneedofconservationtreatment.
NaturalResinVarnishes
Naturalresinvarnishesaresolutionsofresinsobtainedfromthe
sap/exudateofatreeand/orshrubthathavebeendissolvedinasolvent.Theterm
“spiritvarnishes”isalsousedtodescribethesevarnishesalthoughthetermspirit
mayconfuseasitisgenerallythoughtofasreferringtoalcohol.Solution-based
varnishesdrybyevaporation,soproperventilationandprotectionisneededboth
duringpreparationandapplication.Solution-basedvarnishescanbepurchasedpremadebutalsocanbepreparedathome.Thefollowingresinsdescribedbelowcan
allbeclassifiedassolution-basedvarnishes.
• Mastic–Masticiscomposedoftriterpenoidresinscollectedfrompistachio
trees(PistaciaLentiscus)foundthroughoutEurope,India,Turkey,andSouth
Aftrica.Oneoftheoldestnaturalresinsusedinthehistoryofart,masticis
solubleinturpentinesolvents(aswellasalcohol.Althoughthevarnish
appearsclearwhenitisinitiallydissolved,masticisknowntoyellow/darken
anddegradeovertime.WhiletheadditionofUVstabilizers(e.g.Tinuvin292)
canbeaddedtoslowdownthesedegradationprocesses,masticisstillnot
recommendedasafinalvarnishcoating.Masticdoesremainreversibleto
someextentbutitdoesbecomemorepolarovertimeandwillrequiremore
polarsolventsforitsremoval.Thesemore“powerful”solventsmaydamage
thepaintlayersdependingupontheirformulation.Masticisalsosusceptible
tobloomifthepaintingisexposedtoexcessivemoistureand/orhigh
humidityorifthesolventbecomescontaminatedwithwater.Ifartistschoose
toaddmasticintotheirpaintmediums(e.g.megilpandMaroger’sRubens
medium),thepaintwillalsohaveatendencytoyellow,darken,become
increasinglymorebrittle(e.g.pronetocracking),andremainsensitiveto
solvents(aproblemshouldthepaintingneedtobere-varnishedorcleaned).
• Dammar(damar)–Dammarconsistsoftriterpenoidresinscollectedfrom
treesbelongingtotheDipterocarpaceaefamily.LikeMastic,dammarhas
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beenusedasatraditionalpicturevarnish(sincetheearly19thcentury)butis
knowntoyellow/darkenanddegradewithage.Itcanbedissolvedinarange
ofpetroleum-basedsolventscontainingaromaticsaswellasgumturpentine.
Itcantakeanywherebetween10to50yearsfornoticeablesignsof
degradationtoappear;however,theadditionUVstabilizers(e.g.Tinuvin)
canbeaddedtodammartoslightlyslowdowntheseprocesses.Dammar
coatingsarealsosusceptibletobloomifthepaintingisexposedtoexcessive
moistureand/orhighhumidityorifthesolventbecomescontaminatedwith
water.Dammarisnotrecommendedasafinalvarnishcoatingasitexhibits
pooragingproperties;however,thevarnishdoesremainrelatively
removablealthoughitdoesbecomemorepolarovertimeandwillrequire
morepolarsolventsforitsremoval,althoughtoalesserextentthanmastic.If
artistschoosetoadddammarintotheirpaintmediums,thepaintwillalso
haveatendencytoyellow,darken,becomeincreasinglymorebrittle(e.g.
pronetocracking),andremainsensitivetosolvents(aproblemshouldthe
paintingneedtobere-varnishedorcleaned).
SoftandHardCopalResins–Thisclassencompassesawiderangeof
naturalresinsthataretypicallydefinedbytheirplaceoforigin(e.g.Manila
Copal).Softcopals,usuallydissolvedinalcohols,aresimplycollecteddirectly
fromarangeoflivingtrees.Softcopalscandifferinqualityfromonegradeto
thenextandarenotrecommendedasfinalvarnishes.Theseresinsnotonly
sufferfromthesamedegradationprocessasmasticanddammarbutcanalso
becomemoredifficulttoremoveovertime.Hardcopalsarefossilizedand
semi-fossilizedresinscollectedfromthegroundwheretheyweredeposited
fromancientandevenextincttrees.Hardcopalsneedtobecookedathigh
temperaturetoincorporatethemintooilsorsolvents.Theyarenot
reversibleandshouldneverbeusedasfinalsurfacecoatingsforfineart.
SyntheticVarnishes
Itcanbechallengingforartiststonavigatethewiderangeofsyntheticresins
thatarenowavailableonthemarket.Recommendedmaterialsshouldpossessthe
propertiesthataredescribedatthebeginningofthisdocument.Artistsshouldnote
thatmanysyntheticvarnisheshaveyettobetestedfortheirlong-termaging
properties(e.g.propensityforyellowing,etc.).Manysyntheticresinsstillawait
furthertesting;however,theparticularbrands/varnishescitedbelowhavebeen
analyzedbytheconservationcommunityandotherexpertsinthefieldandcan
thereforeberecommendforuseasfinalvarnishesforoil,alkyd,andacrylic
dispersionpaintings.Aswithnaturalresins,artistsareadvisedagainstadding
solublesyntheticresinstotheirpaintmediumasthismaycreateapaintfilmthat
remainssensitivetosolvents,aproblemshouldthepaintingneedtobere-varnished
orcleaned.Finally,artistsshouldchecktoseewhetherUVlightstabilizers(UVLS)
arealreadypresentinpre-madesyntheticvarnishsolutions.Ifnot,artistscan
alwaysaddtheseproducts(e.g.Tinuvin292)themselvesshouldtheychooseto
makevarnishesontheirown.Ingeneral,syntheticvarnishescanbebrokendown
intotwocategories:
• HighMolecularWeight(HMW)resinstendtoproducesurfacecoatingsthat
possessasatintomoderatesheen/gloss.Examplesincludespecificgradesof
polyvinylacetate(PVA)andmethylmethacrylates(e.g.ParaloidB-72,B-67,
MSAVarnish,andotheracrylic-basedvarnishes).Oftenthelatteriscombined
withanotherpolymer(calledacopolymer)toimpartcertainproperties.Note
thatPVAvarnishestendtobedissolvedintoluene,soproperhealthand
safetymeasuresshouldbeexercisedduringpreparationandapplication.
Methylmethacrylatescanbedissolvedinawiderrangeofsolventsincluding
xylene,mineralspirits(notodorless),andinsomecases,water.
• LowMolecularWeight(LMW)resinstendtoproducesurfacecoatingsthat
possessamoderatetohighsheen/gloss.Examplesincludealdehyderesins
(e.g.LaropalA81)andhydrocarbon/styreneresins(e.g.RegalrezorGamvar
varnish).BothLaropalA81andRegalrezcanbedissolvedinodorlessmineral
spirits,mineralspiritblends,and/oraromaticsolvents.
PracticalInformationonVarnishing
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MattingAgents-Mostmattingagentsfoundinvarnishes(andcertainpaint
mediums)aresilica-basedorfinewaxpowders.Suchmaterialsareusually
addedtopre-madevarnishsolutionstoimpartamattingeffecttothe
resultingcoating,essentiallyhelpingtoreducethelevelofgloss.Ingeneral
silicaandwaxadditionsdonotappeartocausesignificantlong-termissues;
however,componentsfromwaxhavebeenobservedtomigratetotheouter
surfaceofthevarnishlayer,creatinganoverallhazyorcloudyappearance(a
phenomenoncalled“efflorescence”).Insomeinstances,waxefflorescence
canbegentlyreducedbyusingasoftbrushorclothbutfordelicatesurfaces
orthicklyimpastoedpaintartistsmightconsiderconsultingaconservator.
Notethatinsomecasesevenafterwaxefflorescencehasbeenreduced,it
oftentendstoreturnovertimeascertaincomponentsinthewaxwill
continuetoremainmobile.Furtherresearchisstillneededtoassesswhether
thereareanylong-termpreservationissuesassociatedwithsomeofthese
mattingagents.
NOTE:Thetypeofwaxaddedcanimpactthedegreeofefflorescencethat
mayoccur.TodayconservatorsoccasionallyuseCosmoloid80H,ahard
microcrystallinewax,asamattingagentintheirvarnishformulations.
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UltravioletLightStabilizers(UVLS)–TherearetwomaintypesofUVLS
additivesusedinthecoatingindustry.Ultravioletabsorbers(UVAs)
preferentiallyabsorbUVlight,therebypotentiallyreducingthebuild-upof
radicalsthatcancauseyellowingandotherdegradationprocessestooccur.
AnothertypeofUVLSarehinderedaminelightstabilizers(HALS)whichcan
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quenchharmfulradicalsandpreventdegradationreactionsaltogether.
Proprietaryvarnishesandcoatingsmaycontainoneortheotherorboth,one
exampleistheTinuvinlineofUVLSadditivesproducedbythecompany
BASF.Tinuvin292isacommonadditive(presentataround2%)thatis
presentinvarnishesintendedforfindartasitiscomposedofaspecificUVA
andHALSblendthathelpstocounteractdiscoloration.Tinuvin292canalso
beaddedtohome-madevarnishesalthoughitisbestpracticetoaddTinuvin
topre-madevarnishesimmediatelybeforevarnishing.Artistsshouldalso
notethatconcentratedTinuvinhasafiniteshelflifeandisbestkeptoutof
directsunlight.Foroutdoormurals,researchhasfoundthatcombinationsof
Tinuvin123and477addedtocertaintypesofcoatingsmayhelpin
counteractingdamageinducedbyextremeexposuretolight.Artistsshould
takenoteiftheychoosetosprayvarnishformulationscontainingthesetypes
ofstabilizers;someareknownskinirritantsandadditionaltestinghasyetto
bedonetodeterminewhethertheycanalsocauserespiratoryproblems.
RetouchVarnishes,“SinkingIn,”and“OilingOut”-Artiststendtoapply
retouchvarnisheswhentheyencounterproblemswith“sinkingin”orareas
ofthepaintthatbegintotakeonamatteorunder-saturatedappearance
(thisisparticularlycommonwithdarkercolors).Sinking-incanbearesultof
a)usingtoomuchsolventtothinthepaintb)usingagroundthatistoo
absorbentorunevenlyabsorbentc)ifthepaintfilmand/orgroundlayers
aretoothinand/orc)ifnotenoughmediumispresentinthepaint.Sinking
incanalsobecausedbythepainterusingtoomuchthinner,whichwill
weakenthebinder’scapacitytomakeafilm,exposingthepigmenttotheair.
Asmostvarnishesavailabletodayareeasilyremovable,itisnot
recommendedtoapplythembetweenpaintlayers.Whileextremelythin
layersofretouchingvarnishmightnotcausefutureproblems,anypaint
appliedatopretouchingvarnishwillbemoresusceptibletodelaminationor
damagecausedduringvarnishremoval(asisoftendoneduringconservation
treatments).Applicationofsuccessivecoatsofretouchvarnishorinterlayers
ofvarnishandpaintcanalsoincreaseapaintfilm’sbrittleness,againleading
topotentialadhesionproblemsandcracking.Oilingoutthesurfaceofa
paintingcanalsobeproblematicasitcanleadtoproblemswithadhesion
andlongtermsolubilityissues.Leavinganexposedlayerofoilmediumona
painting(i.e.regionsofoiledoutsurfacenotcoveredbysubsequentpaint
applications)willcausethesurfacetodarkenand/oryellowovertime(in
additiontobecomingincreasinglydifficulttosafelyremove).Oilingoutcan
bedonecarefullyinbetweenpaintlayers(ortocuttheabsorbencyofthe
ground)duringthepaintingprocessifartistsconsiderthefollowing
recommendationslistedbelow.
AlternativestoUsingRetouchVarnishesandOilingOut
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Considerpossiblyrepaintinganareathathasbecomematteorsunken-in.
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Toaddressproblemswithsinking-in,tryaddingatouchofmedium(heatbodied/thickenedoilsuchasstandoilthinnedinasolvent)toyourpaintsor
aproblematiccolororpigment(i.e.umbersarenotoriousforsinkingin).
Experimentwithdifferenttypesofgroundsaswellastheoverallthicknessto
seeifthismitigatesissueswithsinkingin.Notethatawidenumberofacrylic
dispersiongroundsarenowbecomeavailable,eachwithdifferentamounts
offillers,additives,andwatercontentandsomeofverydubiousquality,so
artistsareencouragedtoperformtestswiththeirbrandofchoice.
Foroilingoutduringthepaintingprocessorforcuttingtheabsorbencyofa
groundartistsarerecommendedto1)applyathinlayerofoillocallyas
neededorglobally(considerusingstandoil/thickenedoilthinnedina
solventifyourpaint/groundlayersareextremelyabsorbent)to
matte/sunken-inareas2)removeanyexcessiveoilusingalint-freeclothand
3)waituntilthesurfaceisdrytothetouch.
Itisparticularlyimportanttoavoidapplyingmoderatetothicklayersof
retouchingvarnishesorlayersofoilduringthepaintingprocessasthiscould
leadtopotentialdelaminationand/orcrackingofthepaint.Asmost
varnishesremainsensitivetosolvents,varnishesshouldnotbeusedasthe
primarypaintmediumorappliedinbetweenpaintlayers.Paintappliedover
avarnishlayerormixedwithcertainamountsofvarnishcanremain
sensitive/solubleshouldtheartworkrequirefutureconservationtreatments.
Ifyourcompositioniscompleteandsomeareasstillappearmatte,locally
applyvarnishinsteadofoiltoevenouttheoverallsheen,waituntildry,then
applyafinalprotectivevarnishovertheentiresurface.
Ifyouchoosetothinyouroilwithsolventsduringoilingouttakecareifyou
areapplyingoverfairlyyoungoilpaintasthesolventsmaybegintobiteinto
thepaintlayersbeneath.
Ifyoursurfaceisprovingtobeparticularlystubbornonceyourcomposition
hasbeencompleted,itispossibletoachieveanevenlevelofglossby
applyingalternatingcoatingsofHMWresins(ParaloidB72,MSAvarnish,
etc.)followedbyaLMWresin(Regalrez/Gamvar).
ApplicationProcesses
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Foroilandalkydpaintings,onemusttypicallywait6monthstoayearin
ordertoensurethatthevarnishdoesnot“sinkin”andbecomeincorporated
intotheslow-curingoilfilm.Acrylicpaintingscanbevarnishedmuchsooner,
anywherebetween2daystoaweekdependingupontherelativehumidity;it
isessentialthatalloftheresidualwaterinthepaintfilmisgivenenoughtime
toevaporatebeforeavarnishcoatingisapplied.
Makesurethatyourpaintingisfreeofsurfacegrimeanddustbefore
varnishing.Alint-freeclothcanbeusedtocleanthesurfaceand/orasoftbristlebrush.
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Duringvarnishapplicationthetemperatureshouldbebetween65and75F
andtherelativehumiditybetween50and75%(toomuchmoistureinthe
atmospherecancausethevarnishtoappearmilkyorcloudy).
Ensurethatyouareselectingtherightsolventforyourvarnish.Usinga
solventthatisincompatiblewithyourvarnishcanresultinstreaksand/or
cloudiness.Artistsarealsoencouragedtopracticewithvarnishformulations
ontestpanelstoensurethattheproperlevelofgloss.
Chooseahighquality,thin,flatbristlebrushthatisanappropriatesizefor
theartwork.Widerbrushestendtoworkbetterforlargerworksand
narrowerbrushesforsmallscalecompositions.
Ifyouareapplyingwithabrushitisbesttoworkonahorizontalsurfaceto
maintainanevensheen.Ifyoumustworkverticallyitissafertoapplythin
applicationsofvarnishtoavoiddrips.
Ifyouwouldliketoavoidusingadditivessuchaswaxesorsilica,trybrushing
thevarnishevenlyuntilithasalmostset.
Ifthesurfaceofyourpaintingappearsnoticeablyunevenpriortovarnishing
orsuffersfrom“sinking-in,”tryapplyingvarnishlocallytospecificareas
beforeapplyinganoverallcoat,waitingatleastonedaybeforeapplication.
Notethatbrushinginavigorousmannermayslightly“bite”intothe
underlyingvarnishsotakecareifyouareapplyingyourfinalcoatusinga
brushratherthanaspraygun.
Avoidapplyingmorethantwocoatsofmatteorsatinvarnishesasthiscan
resultinacloudysurface.Ifyourcompositionrequiresmultiplecoatsitis
besttofirstapplyaregularglossvarnishandfinishwithamatte/satin
varnish.
Alwaysworkverticallywhenapplyingvarnishusingaspraygun.Keepthetip
ofthenozzleparalleltothesurfaceofthepaintingandatafixeddistance
whenmovingfromsidetosideand/ortoptobottom.Itisbesttothinkofthe
spraypatternasa“cone,”withthegreatestconcentrationofvarnishtowards
thecenter.Itisbesttoslightlyoverlappassagesofvarnishinorderto
maintainandevencoat.Finally,avoidusinghighlyconcentratedvarnish
solutionswhensprayingandinsteadapplyapproximatelyfourthincoats.
Morecoatscanbeaddedifmoresheenisrequired.
ADDITIONALRESOURCESANDREFERENCES
”Varnishes,Balsams,Driers,Preservatives,andRetarders”inThePainter's
Handbook:RevisedandExpandedbyMarkDavidGottsegen(NewYork:WatsonGuptill,2006),pp.111-125.
”PictureProtection”inThePainter'sHandbook:RevisedandExpandedbyMark
DavidGottsegen(NewYork:Watson-Guptill,2006),pp.274-279;307-309.
SomeInstancesintheHistoryofDistilledOilofTurpentine,theDisappearingPainters’
Material,byAlanPhenix(LosAngeles:AlanPhenix,2015).
NaturalPigments–SelectingVarnishesforYourPainting
http://www.naturalpigments.com/art-supply-education/selecting-varnishes-foryour-painting/
GoldenPaints–TechnicalInformationonVarnishApplication
https://www.goldenpaints.com/technicalinfo_varnapp1
GoldenPaints–OilingOuthttp://www.justpaint.org/oiling-out-of-dead-colors-inoil-paintings/
GamblinColors–NotesonSurfaceQualityhttps://www.gamblincolors.com/wpcontent/uploads/2016/01/GamblinStudioNotes17_SurfaceQuality.pdf
GamblinColors–VideoDemonstrationsonVarnishing
https://www.gamblincolors.com/tips-and-techniques/video-demonstrations/
AmericanInstituteforConservation(AIC)PaintingsSpecialtyGroupWikion
Varnisheshttp://www.conservationwiki.com/wiki/Paintings#Varnishes_and_Surface_Coatings_.281998.29
AmericanInstituteforConservation(AIC)PaintingsSpecialtyGroupWikionWhite
SurfaceHazeshttp://www.conservation-wiki.com/wiki/White_Surface_Hazes
Smithsonian–MuseumConservationInstitute
http://www.si.edu/mci/english/learn_more/taking_care/painting_varnish.html
KressTechnicalArtHistoryWebsite-InformationonResins
http://www.artcons.udel.edu/about/kress/historic-materials-technicalterms/resins
PhDDissertationonCoatingResearchforOutdoorMurals
http://gradworks.umi.com/35/44/3544103.html

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