20th century artists' oil paints: the case of the Olii by Lucio Fontana

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Available

online

at

ScienceDirect

www.sciencedirect.com

Case

study

20th

century

artists’

oil

paints:

The

case

of

the

Olii

by

Lucio

Fontana

Francesca

Caterina

Izzo

a,∗

_,

_Barbara

_Ferriani

b,1

_,

_Klaas

_Jan

_Van

_den

_Berg

c,2

_,

Henk

Van

Keulen

c,2

_,

_Elisabetta

_Zendri

a,3

a_Ca’_Foscari_University_of_Venice,_Department_of_{Environmental}_Sciences,_Informatics_and_Statistics,_Via_Torino_155/b,₃₀₁₇₄_Venezia_Mestre,_Italy b_Barbara_Ferriani_srl,_Via_Vettabbia_1,₂₀₁₂₂_Milano,_Italy

c_{RCE-Rijksdienst}_voor_Cultureel_{Erfgoed/Netherlands}_Cultural_Heritage_Agency,_Sector_Kennis_Roerend_{Erfgoed/Research}_Movable_Heritage,_P.O._Box_76709, 1070KAAmsterdam,Netherlands

a

r

t

i

c

l

e

i

n

f

o

Articlehistory: Received13June2013 Accepted3November2013 Availableonlinexxx Keywords: LucioFontana FinediDio 20thcenturyoils Contemporarypaintings Manufacturedartists’oils GC-MStechnique Pictorialﬁlms Restoration

a

b

s

t

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a

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t

Duringthe20thcentury,manyinnovativebindershavebeenrapidlyintroducedtotheartworldand soonbecamepopularasartists’paintsandpictorialmedia.However,despitetheadvantagesthatnew syntheticmaterialspresented,oilpaintshaveneverbeenentirelysubstituted.Indeed,thispaperfocuses ontheresultsprovidedbythescientificanalysisofagroupworksfromtheoeuvreofLucioFontana (1899–1968),allofwhichcreatedbetween1960and1964usingoil-basedmedia,andaimstoillustrate howoilscontainedinthepictorialmediahaveinfluencedtheseworks’respectiveageinganddegradation processes.DespitetheapparentcoherenceinthebehaviourofmanyofFontana’screations,someartworks revealeddiscrepanciesintermsofthephysicalandmechanicalbehaviourofthepictorialfilmsand inalterationsresultingfromdegradationprocesses.Samplestakenfromcasestudiesbelongingtothe OliiandFinediDioserieswereanalysedusingopticalmicroscopy,X-RayFluorescence(XRF), Fourier-TransformInfraredSpectroscopyinattenuatedtotalreflectance(FTIR-ATR)andGas Chromatography-MassSpectrometry(GC-MS)inordertostudyandidentifythematerialsemployedbytheartistandthe productsoftheirdegradationprocesses.Theseanalysesgaveunexpectedbutusefulresults(suchasthe presenceofnon-dryingorslow-dryingoilsinthepaintformulations)whichnotonlyprovideduswith newinsightintothenatureoftheconstituentmaterials,butalsofacilitatedtheelaborationofcorrect conservationmeasuresandsuitablerestorationinterventions.

1. Introductionandaimsoftheresearch

During the ﬁrst decadesof the 20thcentury, many innova-tivebinderswereintroducedtotheartworldandsoonbecame popularasartists’paintsandpaintingmedia[1–3].Asadirect con-sequence,thecompositionandnatureofmanyartisticandpictorial binderswerethussubjectedtoradicalchanges.However,despite theadvantagesthatthesenewsyntheticmaterialspresented,oils continuedtodominateasthemostversatilebindingmedium,and haveneverbeenentirelysubstituted[4,5].

Thisresearch, partof a larger researchproject dedicatedto thenature of 20thCentury artists’oilpaints (namely the 20th Century oilpaints Project), dealswith a groupof works by one

∗ Correspondingauthor.Tel.:+390412346730;fax:+390412346729. E-mailaddresses:fra.izzo@unive.it(F.C.Izzo),info@barbaraferrianisrl.com

(B.Ferriani),k.van.den.berg@cultureelerfgoed.nl(K.J.V.d.Berg),

h.van.Keulen@cultureelerfgoed.nl(H.VanKeulen),elizen@unive.it(E.Zendri). 1_Tel.:₊₃₉₀₂₅₈₃_28511;_fax:₊₃₉₀₂₅₈₃_27774.

2_Tel.:₊₃₁₂₀₃₀₅₄₇_10;_fax:₊₃₁₂₀₃₀₅₄₇_00. 3_Tel.:₊₃₉₀₄₁_2346730;_fax:₊₃₉₀₄₁₂₃₄_6729.

of themostimportant Italian artistsofthe 20thcentury,Lucio Fontana(1899–1968).Eventhoughpreviousstudieshaveshown thatFontanahadstartedtousenewsyntheticbindersas substi-tutesfortraditionaloils[6–9],thissurveyfocusedspeciﬁcallyon theanalysisofworksfromtheOlliandtheFinediDioseries cre-atedbetween1960and1964,inwhich,theartistusedtheclassical pictorialmediumofoilswithnewexpressiveaims.Intheseseries, Fontanausuallyappliedmonochromaticpictoriallayerstothe can-vas,then,whilethemediumwasdrying,hepierced,engravedand manipulatedthepaint,whichsoakedintoandaroundtheedgesof theholesandevenleakedontotherearofthecanvas.Theartist appliedtheoilmediainathickimpastousingbrushes,spatulasand hisﬁngersinordertoachieveasculpturaleffect,andsometimes gluedshapedelementssuchassmallpiecesofcolouredglassor sequinsontothesurface.Thepaintlayersoftheworks belong-ingtotheseseriesarenormallycompactandrigid,and seldom presentconservativeproblems.However,withtimesomeofthe pictorialsurfaceshavebeguntoshowtheeffectsofthedrying pro-cessandthemovementofthesupport(whichgenerallymanifest intheformofcraquelures),but rarelyactuallossesinthepaint layeroritsdetachmentfromthecanvashavebeennoticed.Despite the apparentcoherencein the behaviourof many of Fontana’s 1296-2074/$–seefrontmatter©2013ElsevierMassonSAS.Allrightsreserved.

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Pleasecitethisarticleinpressas:F.C.Izzo,etal.,20thcenturyartists’oilpaints:ThecaseoftheOliibyLucioFontana,JournalofCultural Heritage(2013),http://dx.doi.org/10.1016/j.culher.2013.11.003

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2 F.C.Izzoetal./JournalofCulturalHeritagexxx(2013)xxx–xxx

Table1

AshortdescriptionoftheanalysedpaintingsbyLucioFontanaandtheobservationsabouttheirstateofconservationbeforerestoration.

Paintingsa _Description _State_of_conservation

ConcettoSpaziale.Notted’amorea Venezia,1960,FondazioneLucio Fontana(60081),80×100cm

Thisrectangularcanvas,belongingtotheConcettoSpaziale(Olii)series, iscoveredinmonochromaticred-brownpaint;thepictorialsurface presentspunctures,cutsandscratchedincisions

Thereddish-brownpictoriallayerwas wrinkledandwidespreadcraquelure hascreated‘islands’whichtendto detachfromthefabricsupport(Fig.1a). Insomeplaces,thisphenomenonwas soadvancedthatithascausedlossesin thepaintlayer.Insomeparts,thepaint layerappearstobeextremelybrittle andfragile,whileinothers,itisstill stickyandonlypartiallydry ConcettoSpaziale,1962,Fondazione

LucioFontana(62O66), 145×115cm

Thisrectangularcanvas,belongingtotheConcettoSpaziale(Olii)series, iscoveredinmonochromaticpinkpaintwithslashes,cutsandgrafﬁti

ThesethreepinkConcettospaziale artworkspresentedallthesametypeof deterioration:strange,lighteryellow stainsintheformofdropsandpuddles werenotedonthepaintedsurfaces (Fig.1b)

ConcettoSpaziale,1962,Fondazione LucioFontana(1737/92), 100×80.5cm

Thisrectangularcanvas,belongingtotheConcettoSpazialeseries,is coveredinmonochromaticpinkpaintwithslashes,cutsandgrafﬁti ConcettoSpaziale.FinediDio,1963,

FondazioneLucioFontana(63FD 14),178×123cm

Thisovalpainting,belongingtotheConcettoSpaziale(FinediDio) series,ischaracterizedbyamonochromaticpinkpaintwithpunctures, cutsandscratchedincisions

ConcettoSpaziale.FinediDio,1963, FondazioneLucioFontana(63FD 23),178×123cm

Thismonochromaticblackovalwork,belongingtotheConcetto Spaziale(FinediDio)series,presentspunctures,slashesandsequins gluedtothesurface

InthisblackConcettoSpaziale,the edgesoftheslashesappearedtobe deformedandinsteadofprotruding ontotherear,theyappearedtohave contractedandhadpushedthrough ontothefrontofthecanvas(Fig.1c) Concettospaziale.FinediDio,1964,

FondazioneLucioFontana(64FD5), 178×123cm

Thismonochromaticyellowpaintingonanovalcanvaswith punctures,slashesandscratchesbelongstotheConcettoSpaziale(Fine diDio)series

Itdidnotpresentanyunusual alterationsandthereforerepresented anidealreferencestandard(Fig.1d) a_Fontana’s_works_are_classiﬁed_in_the_general_catalogue_by_year,_the_initial_letter_of_the_series_and_the_number_of_the_work_within_its_respective_series_–_hence₆₀_O₈₁ shouldbereadasaworkdatedto1960,belongingtotheOliiseriesandthe81stworkcataloguedinthisseries,andsoonfortheotherpaintingsanalysed.

creations, someworks belongingto theabovementioned series have revealed discrepancies in terms of both the physical-mechanical behaviour of the pictorial ﬁlm and in terms of alterationsresultingfromdegradationprocesses.Ashort descrip-tion of the six works of art and the observations about their state of conservation before the restoration treatments are listed in Table 1. These anomalies could have been inter-preted as the results of ageing, humidity, heat, radiation or previous restoration processes, but with the aim of better understandingtheirconservationconditions and ageing behav-ior, it was decided to investigate the possibility that these anomalies resulted from the nature of the paint composition itself.

2. Experimental

2.1. Samples

Theopportunityofinvestigatingtheaforementionedartworks byFontanawaspresentedwhenthesepaintingsrequired restora-tion,andsampleswereprovidedthankstothegenerosityofthe works’ownersandtheFondazioneLucioFontanainMilan,Italy. Micro-fragmentsoftherespectivepictoriallayersweretakenfrom thebacksectionsorlateralmarginsofthepaintings,someofwhich alsocontainedthegroundlayerofthecanvas.Thesesampleswere foundtobecomposedofdifferentlayersofmonochromaticpaints andinsomecasescontainedglassfragmentsorsequins,gluedby theartistonthepaint.

2.2. Instrumentaldetails

Sampleswereobservedboth invisibleand UVlightwithan OlympusSZX16opticalmicroscopeequippedfor microphotogra-phy.

XRFwascarriedoutusingaBrukerTracerIII-VportableXRF instrument,equippedwithalowpowerRh-tubeoperatingat40kV and2.2uAandapeltiercooledSi-PINdetector.

FTIR-ATRwasperformedusingaPerkinElmerSpectrum1000 FTIRcombinedwithaGrasebySpecacGoldenGateSingleReﬂection DiamondATR,from4000to600cm−1for64scansandaresolution of4cm−1.

GC-MSanalysiswasperformedusingaThermoQuestGC-8000 instrumentwitha SupelcoColumnequity5,30m, 0.25mm,0.5 uminterfacedwithMSMD-800.Theinlettemperaturewas300◦C, theMS interface wasat 270◦C. The temperatureprogram was setfrom120◦C to300◦Cwitha ramp of10◦C/min,3min.The MS was run in Full Scan mode(m/z 40-600), 1.9 scans/s. Sol-vent delay wasset at 4.5min. The transfer line was at 240◦C andthesourcetemperaturewas220◦C.ElectronIonisationenergy was70eV.Sampleswerepreparedusing(trifluoromethylphenyl) trimethylammonium hydroxide, overnight reaction: fatty acids weretransesterifiedintotheircorrespondentmethylesters,while the glycerol reacted forming different (trifluoromethyl)phenyl ethers[10,11].

3. Resultsanddiscussion

Table2fullyreportsthetypologyoftheexaminedsamplesand theanalyticalresultsobtainedbyXRF,FTIR-ATRandGC-MSonthe sixFontana’spaintings.

TheConcettospaziale.Notted’amoreaVenezia(60O81)(detail showninFig.1a)wasanalysedasbothgroundandpictorial lay-ers.Thewhitegroundlayeriscomposedofamixtureoflinseed oilandleadwhite(2PbCO3·Pb(OH)2),withzincoxide(ZnO),

cal-ciumcarbonate(CaCO3)andbariumsulphate(BaSO4)aswhiteners

and/orﬁllers.Thepresenceof aleadsoap wasobserved thanks totheFTIRabsorptionpeakataround1530cm−1:thiswasmost likelyduetotheabsorptionofleadcarboxylatesformedas prod-uctsafter thereactionof the oilbinder withthelead pigment

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this article in press as: F.C. Izzo, et al., 20th century artists’ oil paints: The case of the Olii by Lucio Fontana, Journal of Cultural (2013), http://dx.doi.org/10.1016/j.culher.2013.11.003

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No. of Pages 7 F.C. Izzo et al. / Journal of Cultural Heritage xxx (2013) xxx–xxx ConcettoSpaziale. Notted’amorea Venezia (60O81)

Whitegroundlayer S,Ba.Ca,Zn,Pb Dryingoil Carbonates Calciumsulphate Leadcarboxylates

Saturatedmonocarboxylic(lauric,myristic, palmitic,stearic)anddicarboxylic(suberic, azelaic,sebacic)acids;unsaturated(oleic) acids;glycerol

P/S=1.4 A/P=5.6

Thegroundlayeriscomposedofa mixtureoflinseedoilandleadwhite (2PbCO3*Pb(OH)2)withzincoxide

(ZnO),calciumcarbonate(CaCO3)and

bariumsulphate(BaSO4)as

whiteners/ﬁllers.Itshowsthepresence ofleadsoaps

Thered-brownlayeriscomposedofa modiﬁedlinseedoilpaintwiththe additionofricinoleicacid,mixedwith alizarin

Red-brownpaint TracesofS,Ba.Ca, Zn

(probably contamination fromtheground layer) Oil-basedpaint Organicred dyestuff (1,2-dihydroxyanthraquinone, alsoknownas alizarin,Mordant Red11orTurkey Red) Alizarin

Saturatedmonocarboxylic(palmitic,stearic, arachidic,behenic)anddicarboxylic(suberic, azelaic,sebacic)acids;unsaturated(oleic, linoleic)acids;glycerol;ricinoleicacid P/S=1

A/P=3.2 ConcettoSpaziale

(62O66)

Pinkpaint Zn Oil-basedpaint

Zinccarboxylates Organicred dyestuff Calciumcarbonate

AntinoloRedBalsoknownasThioindigoRedB ((2Z)-2-(3-oxo-1-benzothiophen-2-ylidene)-1-benzothiophen-3-one)

Saturatedmonocarboxylic(lauric,myristic, palmitic,stearic)anddicarboxylic(suberic, azelaic,sebacic)acids;unsaturated(oleic) acids;glycerol;specialunsaturatedfattyacids (erucicandgondoicandtheiroxidation products13,14-dihydroxydocosanoicand 11,12-dihydroxyeicosanoiacids) P/S=3.5

A/P=1.6

Thepinkcolorationisgivenbyanorganicred dyestuff(AntinoloRedB)whitenedwithzinc oxide(ZnO).Calciumcarbonate(CaCO3)was

addedasﬁller/extender.Zincsoapswere detected

Thepaintisanoil-basedpaintcontaining rapeseedoil

ConcettoSpaziale (1737/92)

Pinkpaint AsforConcetto Spaziale (62O66)

AsforConcetto Spaziale (62O66)

AsforConcettoSpaziale(62O66)but P/S=3.4

A/P=1.8 ConcettoSpaziale.

FinediDio (63FD14)

Pinkpaint AsforConcetto Spaziale (62O66)

AsforConcetto Spaziale (62O66)

AsforConcettoSpaziale(62O66)but P/S=3.4

A/P=1.7 ConcettoSpaziale.

FinediDio (63FD23)

Blackpaint Ca,P,Fe,Pb,Zn Dryingoil Prussianblue/black silicates

Saturatedmonocarboxylic(lauric,myristic, palmitic,stearic)anddicarboxylic(suberic, azelaic,sebacic)acids;unsaturated(oleic) acid;glycerol

P/S=1.3 A/P=3.1

Theblackcolorationisduetothe presenceofpigmentssuchasbone blackorivoryblack(Ca3(PO4)2)and

Prussianblue(Fe4(Fe(CN)3)3).The

presenceofquartzandsilicatesis linkedtotheuseofsequins,which wereappliedonthepaintedsurface usingapoly-vinyl-acetate-basedglue Thepaintmediumisadryingoil (linseedoil?) Adhesivefor sequins – Poly-vinyl-acetate (PVAc) – Concettospaziale. FinediDio (64FD5)

Yellowpaint K,Cr,Zn Dryingoil Zinccarboxylates Calciumcarbonate

Saturatedmonocarboxylic(lauric,myristic, palmitic,stearic)anddicarboxylic(suberic, azelaic,sebacic)acids;unsaturated(oleic) acids;glycerol;specialunsaturatedfattyacids (erucicandgondoicandtheiroxidation products13,14-dihydroxydocosanoicand 11,12-dihydroxyeicosanoiacids) P/S=1.7

A/P=1

Thepaintedlayersarecomposedofzincyellow (ZnCrO4+K2CrO4)andanoil-basedpaint

containingrapeseedoilprobablymixedwith linseedoil

Calciumcarbonate(CaCO3)wasaddedas

ﬁller/extender.Zincsoapsweredetected

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Fig.1.DetailsofLucioFontana’spaintingsshowingthedegradationphenomenaandthepeculiarityoftheartist’stechnique:a:Concettospaziale-Notted’amoreaVenezia(60 081);detailofthewidespreadcraquelureandpaintlosses;b:Concettospaziale(62O66);detailofthewhitishspotonthepaintedsurface;c:Concettospaziale-LaFinediDio (63FD23);detailofthedeformationoftheedgesoftheslashes;d:Concettospaziale-LaFinediDio(64FD5);detailofthecutsandslashesonthepaintedcanvas.

[12–14]. The coloration of the red-brown paint is attributable tothepresenceofalizarin,anorganicreddyestuffmainly com-posedof1,2-dihydroxyanthraquinone[15],whilethemediumwas identiﬁedasanoil.Inadditiontotheusualsaturatedand unsat-uratedfattyacids,thepresenceofricinoleicacid,formallycalled 12-hydroxy-9-cis-octadecenoic,wasdetectedbyGC-MSanalysis (Fig.2a).Thismonounsaturatedfattyacidisthemainconstituent (upto95%)ofcastoroil,whichisanon-dryingoilobtainedfrom castorseeds.Itislikelythattheredpaintinthispaintingcontained modiﬁedlinseedoil,thatislinseedoilwiththeadditionofcastor oil,assuggestedalsobythefactthatafter50years,thepainting doesnot appeartohavedried completely.Thepresenceof this oilbindermayexplainsomeofthesignsofdegradationevident inthepictoriallayers(bothhardfracturedandstickyareas),and thewrinklesthathaveformedonthesurfacemightbelinkedto thisuseofcastoroilinthethick,bodiedpictoriallayer.Overtime, theevaporationofvolatilecompounds(suchasalcohols,aldehydes andketones)fromtheoxidativecross-linkingreactionsoccurred, leadingtoweightlosses[16].Asthedryingspeedisslowedbythe

presenceofanon-dryingoil,itispossiblethattheevaporationrate alsooccurredslowly,causingtheformationofmorevisible,deeper wrinkles[17].

Then three ‘pink’ Concetto spaziale (a detail of the painting labelled62O66 isdepictedinFig.1b)werestudied,sincethey demonstratedsimilaritiesregardingthedegradationphenomena (see Table1)and theformulation ofthepaints, theresultsare hereinaftertreatedtogether.Thepinkcolourwasfoundtobethe resultofamixtureofanorganicreddyestuff(likelyAntinoloRedB alsoknownasThioindigoRed)withzincwhite(ZnO)aswhitener. Thebindingmediawereidentiﬁedas dryingoils; moreover,all theFTIR-ATRspectrareportedaclear,broadcarboxylate absorp-tionaround1570-1540cm−1(seethespectrumdepictedinFig.3a). Thesepeaksarepossiblytheresultoftheinﬂuenceofzincwhite inthedryingandageingoftheoilastheycouldrefertothe forma-tionofmetalcarboxylates(soaps)withthecarboxylicacidspresent [12,18].Metalsoapscanbeformedafterhydrolysisof thefatty acidmoleculesinthetriglyceridesofdryingoilswithmetal-based pigments;however,thepresenceofaddedstearatesasdispersion

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, , 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (min) 0 10 20 30 40 50 60 70 80 90 100 Relative Abundance Gly 2C10 _Gly C22 § # Gly C20 C13C18:2 C18:1 C16 C18 2C9 2C8 C19 * Gly 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (min) 0 10 20 30 40 50 60 70 80 90 100 Relative Abundance § * C19 Gly C14 C12 Gly Gly Gly Gly Gly Gly 2C9 2C8 2C10 C16 C18 C18:1 # Gly

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Fig.2. TotalioncurrentchromatogramsofaredsamplefromConcettospaziale.Notted’amoreaVenezia(a)andapinkpaintsamplefromConcettospaziale–FinediDio(63FD 14)(b):a:TICofredsamplefromConcettospaziale.Notted’amoreaVenezia,aftertransesteriﬁcationandGC-MSanalysis(Gly=glycerol,2C8=subericacid,2C9=azelaicacid, 2C10=sebacicacid,C16=palmiticacid,C18:1=oleicacid,C18=stearicacid,C19=nonadecanoicacid,internalstandard,C20=arachidicacid,C22=behenicacid,#=ricinoleic acid,§=ricinoleicacid,methoxy,*₌_{9,10-dihydroxy}_octadecanoic_acid);_b:_TIC_of_pink_paint_from_Concetto_{spaziale–Fine}_di_Dio₍₆₃_FD_14),_after_{transesteriﬁcation}_and_GC-MS analysis(Gly=glycerol,2C8=subericacid,C12=lauricacid,2C9=azelaicacid,2C10=sebacicacid,C14=myristicacid,C16=palmiticacid,C18:1=oleicacid,C18=stearicacid, C19=nonadecanoicacid,internalstandard,*₌_gondoic_acid,_#₌_erucic_acid).

agentsinthepaintformulation[19,20]cannotbeexcluded.Aminor additionofcalciumcarbonateasaﬁllerorextenderissuggestedby carbonaticabsorptionpeaksat1413and873cm−1.Amongstthe characteristicdryingoilcompounds,twouncommonfattyacids weredetectedbyGC-MSanalysis(Fig.2b):erucic(13-docosenoic) and gondoic (11-eicosenoic) acidsand their oxidation products (13,14-dihydroxydocosanoicacidand11,12-dihydroxyeicosanoic acidrespectively).Theseunsaturatedfattyacidsareconsideredto bebio-markersastheyarepresentonlyinoilsobtainedfromthe seedsofBrassicaceae,suchasrapeseedoil[21].Moreover,theP/S ratiosforthepinkworksarearound3.6andmayrefertotheuse ofrapeseedoil(whoseP/Sisaround3.5–3.8)asbindingmedia. Thisisasemi-dryingoilwhichwasintroducedinthe20thcentury accordingtomodernartists’handbooks[4,5].Thehighcontentof oleicacidandtheconsequentiallyhighdegreeofunsaturationis mostlikelytobeaconsequenceofthepresenceofaslow-drying oil,butthisphenomenacouldalsobeexplainedinanotherway–in fact,thesigniﬁcantamounts ofoleicacidmaybelinkedtothe presenceofzincoxide,whichhavealsobeennotedinother art-works.It would thus appearthat in anoil-basedmedium, zinc oxideformsapackedstructurewhichisabletotrapoleicacidin

thepictoriallayer:thiseffectcanalsooccuryearsafterthe oxida-tionprocessends[22–24].Theunusualdegradationphenomena observedinallofthesepaintingsmightbetheresultofthe pres-enceofaslow-dryingoil(rapeseedoil)containingalargeamount ofunsaturatedacids(oleic,erucicandgondoicweredetectedafter almost50years)whosetriglyceridesreactedwithzincwhitefrom the painted layers to form metal soaps. As FTIR analyses sug-gest, metal soapsare present in the formof zinc carboxylates, and henceit is probablethat zinc soapsarepresent as formed and/oraddedsoaps(asdispersionagents)andthattheymigrated and conglomerated on the surface, forming the light yellow spots.

Althoughit didnot showany evidentdegradation phenom-enaonthesurface (Fig.1d),similar resultswerefoundfor the artworknamedConcettospaziale.FinediDio,(64FD5).The yel-lowcolorationisduetotheuseofzincyellow(ZnCrO4+K2CrO4)

(seeXRFreportedinFig.4), whilethemediumisanoil.GC-MS resultsarecomparablewiththepinkseries:besidesthepresence ofcommonfattyacids,theyellowpaintexhibitshighamountsof unsaturatedoleic,gondoicanderucicacids.Thepresenceof rape-seedoilis alsosuggestedin this case,although theP/Sratiois

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72 2 77 0 79 5 8 73 50 60 70 80 90 100 %T 8 11 0 1 11 61 12 41 13 2 0 14 1 3 15 3 9 15 72 17 39 28 5 1 29 1 9 33 3 4 0 10 20 30 40 1000 1500 2000 2500 3000 3500 4000 Wavenumbers (cm-1) 47 5 60 5 63 1 79 5 94 6 11 2 2 14 3 4 29 26 29 72 50 55 60 65 70 75 80 85 90 95 %T 10 22 12 40 13 7 2 17 37 5 10 15 20 25 30 35 40 45 1000 1500 2000 2500 3000 3500 Wavenumbers (cm-1)

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Fig.3.FTIR-ATRspectraofthepinkpaintinConcettospaziale-LaFinediDio,(63FD14)(a)andoftheadhesiveusedtogluesequinsinConcettospaziale-LaFinediDio,(63FD 23)(b):a:FTIR-ATRspectrumofthepinkpaintinConcettospaziale-LaFinediDio,(63FD14);b:FTIR-ATRspectrumoftheadhesiveusedtogluesequinsinConcettospaziale-La FinediDio,(63FD23).

1,7-this valuesuggeststhemixturewithotheroilmedia(such asthetraditional linseed oil). Asobserved inthe pinkOlii,the abundantoleicacidcontentmightberelatedtotheactionofzinc pigmentsandthebroadFTIRpeakat1574cm−1canbeexplained bythepresenceofzincsoaps,formedand/oraddedinthepaint formulation.

ThelastanalysedpaintingisablackConcettospaziale–Finedi Dio(63FD23)(Fig.1c),whosecolorationisduetothepresenceof pigmentssuchasboneblackorivoryblack(Ca3(PO4)2)andPrussian

blue(Fe4(Fe(CN6)3)).Fromsamplestakenfromthepictoriallayer

(includingareasinwhichthesequinswerepresent),itwas ascer-tainedthatitwasaoil-basedpaint.Thehighdegreeofunsaturation associatedwiththehighcontentof oleicacidsuggeststhatthe paint,even50yearsafteritsapplicationtothecanvas,isstill imma-tureorthatanon-dryingoilwasaddedtothepaint.TheP/Sratio is1.3,valuewhichisconventionallyreferredtolinseedoil[25]; nevertheless,theuseofthistraditionalbinderisrather improb-able,duetothedifferentbehaviorshown bythepictoriallayer underexamination.Itislikelythatotherlipidicbinders, exhibit-ingsimilarP/Sratio,wereemployed[4,5,11,21].Inthissample,the

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Tube Voltage: 40.0 kV current: 2.2 uA

Cr

Zn

0 5 10 15

0

x-ray energy (keV)

K

Cr

Zn

Fig.4. XRFspectrumofayellowpaintsamplefromConcettospaziale-LaFinediDio (64FD5).

sequinsappearednotonlytobeembeddedinthepictorialfilm, butinsomeplaceswerealsoembeddedinasuperficiallayerof polyvinylacetate(PVA)-basedadhesive(mostlikelytobeVinavil®, producedbytheItaliancompanyMontecatini)(Fig.3b).Thisglue couldhaveplayedaroleinthecreationoftensionsandthe defor-mationofthepictoriallayers,howeverthereisalsothepossibility thatthisalterationcouldbecausedbytheextremethinnessofthe pictorialfilm.

4. Conclusions

Theresultsobtainedbythisstudyhaveprovideduswith impor-tantinformationregardingtheworksoftheOliiseriescreatedby LucioFontanabetween1960and1964.Duringthesameperiod,the artistexperimentedwithseveraldifferentandinnovativepictorial binders,butstilltendedtowardsmoretraditionalbinding materi-als.Fontanahimselfwasknowntobeanexperimentalartistand heusedtomixhousepaintswithmanufacturedoilpaints[7–9]. Nevertheless,aswehaveproven,Fontanausedoilpaints contain-ingdifferentlipidicbinders: anon-dryingoilsuchascastoroil, asemi-dryingoilsuchasrapeseedoilandthetraditionaldrying binder,linseedoil.ItisnotclearifFontanawishedtoexperiment withdifferentkindsofoilsinordertoachievedifferenteffectsor ifhesimplyusedreadymadepaintswithoutknowingtheir com-position,however,thematerialsandthetechniquesthatheused arenowproventobecloselylinkedtotheconservationproblems exhibitedbythepictoriallayersandobservedduringconservation treatments.Furthermore,theseanalysesgaveunexpected,but use-fulresultswhichnotonlyprovideduswithnewinsightintothe natureoftheconstituentmaterials,butalsofacilitatedthe identi-ﬁcationofsuitableconservationmethods.

From an analytical point of view, this study has reinforced previouslystatedconclusionsthatmaintainthatmodernand con-temporaryartistsusedandstillusevaryingformsofthistraditional medium–which areoftengenerically labelledas‘oils’–without anyspeciﬁcregardtotheirbindingproperties.Theuninformeduse oftheseoilsdemandsthateachcasestudybeanalysedseparately inordertodevelopsuitabletreatmentmethodsforeachandevery workandavoiddetrimentalgeneralisations.

Acknowledgements

Thisresearchprojectwasmadepossiblethankstothe collabo-rationoftheFondazioneLucioFontanainMilanandistheresultofa

collaborationbetweentheCa’FoscariUniversityofVeniceandthe NetherlandsCulturalHeritageAgency/RCE(Rijksdienstvoor Cul-tureelErfgoed,formerlyICN-InstituutCollectieNederland)andis partofthewider20thCenturyoilpaintsProjectcarriedoutbyRCE incooperationwiththeCourtauldInstituteofArt(CIA),theGetty ConservationInstitute(GCI)andtheTate.SpecialthanksgotoDr. LucMegensandDr.SuzanDeGrootofRCEfortheirassistancein performingXRFandFTIR-ATRanalyses.

Thisstudywasﬁnanciallysupportedbythe2008–2010PRIN Project“Behaviourofpolymericpictorialﬁlmsandmethodsforthe conservation”.

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