Science, value and material decay in the conservation of historic environments

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Original

article

Science,

value

and

material

decay

in

the

conservation

of

historic

environments

Rachel

Douglas-Jones

_,

_John

_J.

_Hughes

_,

_Siân

_Jones

_,

_Thomas

_Yarrow

a_{TechnologiesinPracticeResearchGroup,ITUniversityofCopenhagen,RuedLanggaardsVej7,2300Copenhagen,Denmark} b_{SchoolofEngineeringandComputing,UniversityoftheWestofScotland,PaisleyCampus,ScotlandPA12BE,UnitedKingdom} c_{SchoolofArts,LanguagesandCultures,UniversityofManchester,Manchester,EnglandM139PL,UnitedKingdom}

d_{Anthropology,DurhamUniversity,DawsonBuilding,SouthRoad,Durham,EnglandDH13LE,UnitedKingdom}

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t

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Received5August2015 Accepted18March2016 Availableonline19April2016 Keywords:

Value

Qualitativeresearch Scienceandtechnology Authenticity Decay

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Thehistoricenvironmentundergoescyclesofmaterialdeterioration,andtheseprocesseshavea pow-erfulimpactonthemeaningsandvaluesassociatedwithit.Inparticular,decayinformstheexperience ofauthenticity,asatangiblemarkofageand‘thereal’.Thisarticleexaminestheintersectionbetween materialtransformation,scientificinterventionandculturalvalue.Drawingonqualitativesocialresearch atthreeScottishhistoricbuildings,weshowthatthereareacomplexrangeofculturalvaluesand qual-itiesassociatedwithmaterialtransformation.Furthermore,wehighlighthowtheuseofscience-based conservationtocharacterise,andintervenein,processesofmaterialtransformationcanaffectthese val-uesandqualities.Wearguethatitisnecessaryandimportanttoconsidertheculturalramificationsof suchinterventionsalongsidetheirmaterialeffects.Thisrequiresacase-by-caseapproach,becausethe culturalvaluesandqualitiesassociatedwithmaterialtransformationarecontext-specificandvarywith differentkindsofmonumentsandmaterials.Weconcludewithaseriesofrecommendationsaimedat integratinghumanitiesandscience-basedapproachestotransformationinthehistoricenvironment.

©2016TheAuthors.PublishedbyElsevierMassonSAS.ThisisanopenaccessarticleundertheCCBY license(http://creativecommons.org/licenses/by/4.0/).

1. Introduction

Stone,brickandmortararethemostwidespreadmaterials mak-ingupthehistoric-builtenvironmentthroughoutEurope,andto varyingdegreesinotherpartsoftheworld.Inthisarticle,welookat thevulnerabilitiesofsuchmasonrymaterialstodeteriorationand decay,andthewaysinwhichheritagescienceinterventions inter-sectwiththerangeofculturalvaluesandqualitiesassociatedwith suchmaterialtransformation.Thecoreofourargumentisthatthe assessmentofvaluesassociatedwithmaterialtransformation–and thescopeandpotentialeffectsofscientificintervention–requires acase-by-case approach.Thespecificvalues andqualities asso-ciatedwithmaterialtransformationarecomplex,situationaland contextual.Consequently,itisnotpossibletoidentifysimplerules ormodelsthatcanbeapplieduniversallyacrossdifferentheritage sites,evenincaseswherethesameprocessesofmaterial trans-formationareatwork.Instead,qualitativesocialresearchshould

∗ Correspondingauthor.

E-mailaddresses:[email protected](R.Douglas-Jones),[email protected] (J.J.Hughes),[email protected](S.Jones),[email protected] (T.Yarrow).

beusedtoexplorehowmaterialtransformationisinvolvedinthe creationandnegotiationofvaluesatspecifichistoricbuildingsand monuments.Ourargumentsarebasedonresearchcarriedoutat threecasestudysitesinScotland,during2013–14.Thisresearch showsthatmaterialtransformationisassociatedwithawiderange ofoverlappingattitudesandvaluesamongstbothheritage profes-sionalsandvisitingpublics.Furthermore,thereisnobasis fora prioridistinctionsbetweenformsofdecaythatarepositively val-uedandthosethatareconsideredundesirable.Ouranalysisreveals thatvaluesassociatedwithmaterialtransformationareinformed bycomplexrelationsbetweenmaterials,decayprocesses,typesof monument,visitorexpectations,formsofexpertiseanddemands onuse. Inourconclusions, weexamine theimplicationsof the researchproject,andproviderecommendationsforpractitioners innavigatingthechangingfaceofvalue-orientedconservation.

Collaboration between the sciences and the humanities is centraltotheAHRCScienceandHeritageresearchproject under-pinning this article (www.uws.ac.uk/mavproject/).The research teamhasexpertiseinheritagescience(Hughes,PI),cultural her-itage(Jones)andsocialanthropology(Douglas-JonesandYarrow). WorkinginpartnershipwiththeNationalTrustforScotlandand HistoricScotland,ourcasestudiesextendtherangeofthis inter-disciplinary dialogue, incorporating heritage professionals with http://dx.doi.org/10.1016/j.culher.2016.03.007

backgroundsinarchitecture,conservation,heritagemanagement, engineeringandarangeofdifferentkindsofheritagescience.A stakeholderworkshopalsoprovedafruitfulcontextfor interdis-ciplinarydiscussionanddebate.Previousethnographicresearch carriedoutwithHistoricScotlandbetween2010and2013[1]also informstheargumentspresentedinthisarticle.

In advancing interdisciplinary understandings of the values attachedtomaterialtransformationinthehistoricenvironment, wepayspecificattentiontohowtheseinform,andareinformed byscientificinterventions.Wedefineheritagesciencebroadlyas anythinginvolvingtheapplicationofscientificmethodsfor mea-suringchange,analysingmaterials,protectingthemfromdecay, andconsolidatingvulnerablecomponents[2,3].Thisencompasses acommondistinctionbetweenapplicationsofsciencetoadvancing understanding (of both material change and heritage environ-ments), and intervening to modify, manage, or arrest material change[3].Thelatterareaissometimesreferredtoas‘conservation science’[4]andincludesbothpreventiveconservationbasedon sci-entificunderstandingsofagenciesandprocessesofdeterioration (sometimesreferredtoas‘environmentalconservation’),aswell asremedialconservation,whichmayincludeaddingorremoving materialsusingtechniquesoriginallydevelopedthroughscientific research.

2. Researchcontext

Masonrymaterialsarevulnerabletodeteriorationand decay undertheinfluenceofavarietyofphysicalandchemicalagencies. ‘Weathering’encapsulatesa rangeofprocesses drivenby mois-turemovement,drivingrain,freeze-thawcycles,saltcrystallisation andchemicalattackfrompollutants[5,6].Biofilmscanhavea sig-nificantimpactonhistoricmasonry,includingstaining,moisture movementandphysicalstresses[7].Climaticvariabilityalsobrings aboutchangetophysicalenvironmentalconditions,forinstance increasedrainfallexacerbateswateringressandincreased biolog-icalgrowth[8,9].

Inconservation contexts,responses totheseforms of mate-rialdegradationoftenresultinstepstomeasure,record,protect, and/orrepairhistoricbuildingsandmonuments.Thereisalong andcontinuingtraditionofregularrepairandmaintenanceusing traditionalcrafttechniquesandmaterials.However,the develop-mentofheritagescienceduringthetwentiethcenturyhasledtothe introductionofnewtechniquesformeasuringchange,analysing materials,protectingthemfromdecayandconsolidating vulner-ablecomponents[2,3,10].For instance,petrographicanalysis is usedfor characterisation andthe determination ofprovenance. Biocides havebeen developed for themanagement of biofilms. Morerecently,thepotentialofself-cleaningsurfacetreatmentsand waterrepellentsisbeingexplored[11].Nanotechnological consoli-dantsevenpromisethepossibilityofconsolidationandrestoration throughthecreationofnewfabric[12].Asaresultofthese tech-niques,thenatureofhistoricbuildingsandmonuments,andtheir dynamicrelationswiththeirphysicalenvironments,isalteredto somedegree,whetherdirectlyorindirectly.Forinstance,ratesof weatheringcanbemodifiedandsignsofwearandageremoved. Historicfabriccanalsoberemovedandnewmaterialintroduced. Butwhatoftheimpactofsuchscience-basedinterventionsonhow heritagesitesareexperiencedandvalued?

Heritageconservationandmanagementisacomplexprocess involving not only physical fabric, but also cultural, aesthetic, spiritual,social and economic values [13–15]. Indeed, a recent reportfromtheGettyConservationInstituteassertsthat“the ulti-mateaimofconservationisnottoconservematerialforitsown sakebut,rather,tomaintain(andshape)thevaluesembodiedby thatheritage”([16]:7,ouremphasis).Furthermore, understand-ingsofauthenticityandsignificance inconservationphilosophy

haveundergoneradicalchangeoverthelastthreedecades,with increasingemphasisontheintangibleaspectsofheritageplaces [17,18].Nevertheless,thematerialsmakinguphistoricbuildings andmonuments,andthetransformationstheyundergoovertime, areintegraltothevaluesproducedinrelationtothem.Stoneis valuedforitsaestheticproperties,beingcharacterisedbyan out-standingrangeofcolours,textures,andstateoffinish,whilstits bulklendsitselftoelaboratemouldingand carving.Its durabil-ityisvalued, butequallyweatheringand wearoftencontribute toperceived‘character’.IntheEuropeanconservationmovement, suchmaterialtransformationhasbeenseenasimportanttestimony tothepassageoftimeandtheauthenticityofamonument.The valueoftransformationinthissensewasepitomisedbythe Roman-ticidealofthemediaevalruincreatedatthehandofnature[19],and formalisedbyAloisRiegl[20]intheconceptof‘agevalue’wherein visibledecayanddisintegrationofmaterialfabricembodiedthe passageoftime,theageofthematerialaffected,andwas immedi-atelyandaestheticallyaccessible.Decayanddisintegrationarealso centraltotheconceptofpatinaanditsassociatedaesthetic quali-tiesofharmonyandbeauty([21]:435–437;[19]:148–182;[22]). Patinathereforehascometorefernotonlytophysicalchanges– dents,chips,oxidisation–butalsoqualitativeexperiencesofthese changeswithinanaestheticregister.Mortars,rendersand plas-ters,whilstoftenlessdurablethanstoneitself,andintentionally subjecttogreaterrenewalovertime,canalsoenhanceordetract fromassessmentsofagevalueandauthenticity.

Despite long-standingrecognitionof thevalues surrounding ageing,decay,patinaandruination,therehasbeenrelativelylittle researchinthisspecificarea[21,23,24].Conservationapproaches increasinglyemphasisetheneedtoconservethevaluesembodied inheritage,asmuchashistoricmaterialitself[16].Thisrequires greaterattentiontothewayinwhichthesevaluesenterinto con-servationdecision-making.Conservatorsareoftenacutelyawareof thevalueofpatina,althoughClifford[25]hasneverthelesscalled formoreinvestigationintoitsculturalsignificance.Incontrast,the natureofexperimentalinvestigationmeansthatheritagescientists oftenextractmaterials,propertiesandprocessesfromtheir phys-icalandsocialcontext.Whiletherearewide-ranginganddetailed studiesoftheimpactofscientifictechniquesonthematerialfabric itself,therehasbeenlittleinvestigationintotheirimpacton cul-turalmeaningsandvalues.Indeed,itcouldbearguedthatmuch appliedresearchhasbeendrivenbyspecificscientificframeworks, withlimitedconsiderationofpossibleimpactsonissuesof authen-ticityandhistoricvalue.AsCassar([26]:9)emphasises,weneed tounderstandhowvalues areaffectedbymaterial change.Yet, wealsoneedtoaskhowscience-basedapproachesfor measur-ing,analysingandmodifyingmaterialtransformationimpacton thevaluesofheritage?Furthermore,howdothevaluesassociated withmaterialtransformation,andthewiderculturalsignificance ofheritage,impactontheuseofheritagescience?Toanswerthese questions,itisnecessarytodrawonhumanities-based methodolo-gies.

3. Methods

Qualitativesocial research methods areincreasingly used in heritagemanagementtoprovideevidenceforvalue-based conser-vationandsignificance assessment[1,17,27,28].Thesemethods, includingsemi-structuredinterviewsandparticipantobservation, areparticularlysuitedforexaminingthecomplexmeaningsand valuesthatsurroundhistoricbuildingsandmonuments[29]. How-ever, they are rarely employed to understand the values and qualitiesspecifically associatedwith thescientific management ofmaterialtransformation.Inourresearch,weusedparticipant observationandinterviewingtogaininsightintothevalues associ-atedwithmaterialtransformationandtheuseofheritagescienceat

threeheritagesites.Researchofthiskindisnecessarilycontextual. Ourmethodologyisunderpinnedbytheassumptionthattheways peopleseektounderstandandgivemeaningtotheworldhaveto beunderstoodinrelationtothecontextsinwhichtheycomeinto play.Thiscontextualapproachnecessarilyinvolvesaninductive methodology:whileweestablishedasetofresearchquestionsat theoutset,theformandshapeofsubsequentinvestigationswere alsoinformed(andmodified)throughongoingconsultationswith researchpartnersandparticipants.

Thethreecasestudieswefocusoninthisarticlewereprovided byourresearchpartners,HistoricScotland(HS)andtheNational TrustforScotland(NTS):DryburghAbbey;SkelmorlieAisle;and CharlesRennieMackintosh’s HillHouse.Eachofthesesiteswas selectedbecauseit hassignificantconservationissues resulting frommaterialtransformation,withassociatedscientificresearch and/orintervention.Theyalsoallowustoexploretheinteractions ofarangeofvariables,including:(i)differentbuildingtypesand materials;(ii)site-specificconservationproblems,approachesand interventions(includingdifferentscientificapproaches);(iii) vary-ingconstellationsofstakeholderinterests,valuesandopinions.

FieldresearchwasconductedbetweenMarchand July2013, andconsistedofinterviewswithheritageprofessionalsandvisitors. Theanthropologicalmethodof‘participantobservation’wasalso employed,involvingsustainedsystematicobservationofrelevant contexts,toascertainhowsocialvaluesandpracticesaredrawn intoeveryday interactions. Thistechnique wasused in a range ofsituations,includinglaboratoriesandworkshops,during con-servationmeetings,siteinspections,andguidedtoursforvisitors. Initialdiscussionsandconversationsatthecasestudysitesformed thebasisforsubsequentin-depthinterviews,whichexplored con-servation practices, decision-making, and attitudes to material transformation.Arangeofheritageprofessionalswereinterviewed, includingheritagescientists(mainlywithgeo-materialsexpertise), appliedstoneconservators,preventativeconservators,managers, stonemasons, and architects. Interviews were transcribed and analysedusingqualitativedataanalysissoftware,NVivo.Shorter informalinterviewswerealsoconductedwithvisitors,andvisitor booksconsulted,toexploretheirexpectationsassociatedwitheach site,theirperceptionsofhowthematerialfabricofbuildingswas changing,andhowtheyfeltaboutformsofscientificintervention. Foreachofthecasestudysites,asystematicliteraturereviewwas alsoundertaken,focusingonkeyconservationandmanagement documents,aswellasassociatedscientificreports.

4. Materialtransformationandtheproductionofvalue

The research results provide evidence for a broad range of responsestomaterialtransformationandviewsonhowitcould, andshould,bemanaged.Manyofourintervieweesoverthecourse of the study expressed positive values associated with ageing, weatheringand decay.Formostvisitorstothecasestudysites, marksofage,weatheringanddecayplayedanimportantrolein establishingtheauthenticity,significanceandaestheticappealof buildingsandmonuments,asidentifiedbyRieglandRuskinovera centuryago.AsoneGermanvisitortoDryburghputit,“Iwouldn’t wantanynewthings.Theyshouldtrytokeepitasitis.Welike ruins,thereisamystificationandrespectfortheprojectsofour ancestors.”Similarly,aCanadiantouriststressed,“weliketosee somedecay,tosee theageofa building”.Somevisitors, when askedinmoredetailaboutmaterialtransformation,focused partic-ularlyonsurfacewear,whichtheysometimesreferredtoas‘patina’. Theimpactofhumanactivity,suchaswearonthetreadofastair orabannister,mightalsobeparticularlyvaluedasanindicator ofauthenticity,thepassageoftimeandasenseofconnectionto generationspast[17,21].

Professionals involved in managing and conserving historic buildingsandmonumentsexpressedsimilarviewsonthepositive valueofcertainkindsofmaterialtransformation.Asoneproperty managerputit,“Ithinkofthesurfaceofanobject,oramaterial, that’sbeenlaiddownovertime...It’simportant,formostofus, inthepleasureoflookingatthisthing”.Agewasalsovaluedasa markofauthenticitybyourprofessionalinterviewees,asexpressed bythisarchitect:

IwenttoAbbotsford*recently,andtheyhadn’tcleanedallthe lichenoffthestoneworkandthatpatinaIthoughtaddedalotto theappreciationofthebuildingasbeingoneoftheearly19th century.Ithadbeenthereforthatlengthoftime.(*19th_Cdwelling oftheauthorWalterScott,neartoDryburgh)

For mostheritage professionals, theirapproach to the man-agement of material transformation was also framed by their anticipationofthevaluevisitorsmightattachtoit.Thus,in consid-eringconservation strategies and reaching decisions withtheir colleagues,heritageprofessionalsfrequentlyconsideredhowtheir workwouldbeseenandwhatkindof‘public’reactionstheywould encounter,althoughvisitorswererarelydirectlyconsulted.

Materialtransformation certainly produces qualitiesthatare valuedinpositiveways,butitisalsoassociatedwiththe prospec-tivelossofthehistoricbuildingormonumentitself.Mostheritage professionals recognise a version of the dilemma articulated byLowenthal ([19]:126):whiledecay underminesauthenticity through destructionof fabric, conservationcan alsoundermine authenticitythroughartificiallyarrestingvalued formsof mate-rial transformation associated with ageing.Here, a moral duty andaccompanyingresponsibilityisplacedfirmlyinthehandsof thosewholookafterheritagesites:‘iftheydon’tgetitright’, com-mentedonevisitor‘thethingisgoingtogo,andit’sgoneforever, forfuturegenerations’.Inturn,heritageprofessionalsinternalised thismoralduty,asoneputit:‘Ifwedon’tstopthedecay,we’ll losethemonument’.Thoseintervieweeswhodiscussed‘decay’and ‘patina’directlyoftenplacedthetwotermsonaspectrumof mate-rialtransformations,distinguishedbythespeedanddepthofthe process,aswellasthedegreeofthreatassociatedwithit.Asone propertymanagerexplained,patinacanbemanagedfromastate ofbeing‘aged’andaestheticallyattractive,to“apointwhere sud-denlyyou go,butnow it’sdetrimentaltothefabric”.However, there is considerablevariation in terms of howmaterial trans-formation isvalued and whenit isdeemed harmful.Moreover, differentperspectivesoftenrelatetodifferentkindsofexpertise, andtheformsofskilledvisionandpracticeassociatedwiththem [1].

Formostprofessionals,heritagescienceisrecognisedashaving averyimportantroleinterms ofinvestigating and understand-ingmaterialtransformation.Asonepreventativeconservatorput it,‘scienceisalreadydoingalot,withthermography,X-ray diffrac-tion,environmentalmonitoring,petrographicstudies.Itisbuilding upthepictureofwhatyouhave’.Scientificevidenceresearchwas consideredimportantinmeetingtheobligationforan evidence-based approach:‘wecanjustify ourdecisionsbecausetheyare basedonobservation,andresearch’.Atthesametime,our inter-viewsrevealedawidelyheldview,amongstarchitectsandheritage managersinparticular,thatscientificresearchshouldnotbethe only means bywhich a buildingis understoodor valued. Fur-thermore,newkinds ofintervention basedonheritage science, suchasconsolidantsandcoatings,arousedgreaterambivalence. For manyheritage professionals,theunknownconsequences of newtreatmentsare asourceof concern,andlaboratorytesting is notseen asa substitute for ‘real-world’conditions.The con-cernexpressedrelatesultimatelytotheissueofauthenticity,and theperceivednegativeimpactofmaterialsthatareregardedas ‘artificial’.

Inturn,visitors’perceptionsofsites,aremediatedinmoreor lessdirectways byscientificallybasedunderstandings ofthem. Informationconveyingthefindingsofscientificinvestigationsis oftenpositivelyvalued,beingtakenasasignof‘care’.These find-ingsalsodirectlymediateunderstandingsoftheauthenticity,both throughpositiveidentificationoforiginalfabric,butalsothrough resultsthat cansometimesundermine thevisitorexperienceof whatisgenuine.Forvisitors,scientificallyderivedand industri-allyproducedmaterialswereoftenequatedwith‘artificiality’,the erosionofthevalued‘naturalness’ofmonuments.Asone Ameri-canreligioustouristputit,‘Thereissomethingpowerfulinknowing thatthestonemason’sworkof800yearsagoisstillhereonitsown merits.Itwouldbe...<hegrimaces>toknowit’sbeenproppedup artificially,orbychemistry’.

Theresearchthusconfirmsthatmaterialtransformationis asso-ciatedwitharangeofpositivevalues,butthatitisalsoassociated inanegativesensewiththeultimatelossofboththehistoricobject itselfand the values associatedwithit. For thesubjects ofour research,theuseofscienceforpreventionandunderstandingwas associatedwithadifferentsetofmeanings,comparedtothemore interventionistuseofscienceinremedialtechniques.Inrelationto theformer,sciencecanbeseenascontributingtothe understand-ingofwhatis‘real’andhence‘authentic’.Bycontrast,scientifically basedinterventionsareoftenregardedmoreambivalently, hav-ingthepotentialtoupholdbutalsotoundermineauthenticity,for examplethroughtheintroductionofnewmaterialsandtechniques thatmaybeseenas‘unnatural’andwhoselong-termconsequences areunknown.However,suchgeneralizationshavetheirlimitations. Inwhatfollows,wedemonstratehowvaluesassociatedwith mate-rialtransformation emergeatspecificcasestudysites,andhow theseareinformedbythenatureofthosesitesandthematerial transformationtheyexhibit.Itwillbeshownthatthesevalues,and thenotionsofauthenticityassociatedwiththem,arehighly con-textual,dependingonthematerialsinvolved,thetransformation processesatwork,thewidersignificanceofthesite,andtheforms ofexpertiseapplied.

5. Casestudiesanalysis

5.1. DryburghAbbey,ScottishBorders

OurfirstcasestudyfocusesonDryburghAbbey,asitethathas beenactivelycuratedasaromanticruin,intimatelyassociatedwith ideasof‘naturaldecay’.Althoughthisdatesbacktoeighteenth cen-turyinterventions,itremainsanimportantaspectofthecultural significanceofthemonumentanditsconservation.Asweshow, romanticideasaboutdecayandruinationthusframethekindsof scientificresearchbeingundertaken,andcompeting understand-ingsof‘appropriate’interventionsarisingfromthesefindings.

DryburghAbbey(Fig.1)wasfoundedinthe1150sbythe Pre-monstratensians ona bend in theRiver Tweed, approximately 60kmsouthwestofEdinburgh.Itisatypicalmediaeval,European religiouscomplex,builtinthegothicstyleusinglocallysourced sandstone.Itswallsare>1mthick,composedofcoursedashlar ontheexteriors,andfilledwithlimeandrubble.Internalsurfaces wouldtypicallyhavebeenlimeplastered,butmostofthisislost now.Itspost-Reformationbiographywasstronglyinfluencedby DavidErskine,founderoftheSocietyofAntiquariesofScotland, whocurateditintheimageofaromanticruininthelate eigh-teenthcentury.Itisascheduledancientmonumentinthecareof HistoricScotland(HS)anditisopentothepublicthroughoutthe year.

ThepartiallysubterraneanChapterHouseisoneofthefew sur-vivingroofedpartsoftheAbbey,althoughithasadoorlessentrance andunglazed windows.Thisstructure hasnationalsignificance

Fig.1. EarlyGothic(12–13thC)roundedarchdoorwayattheremainsofDryburgh Abbey,ScottishBorders.ThisdoorwayisthesouthentrancetotheChoir,adjacent totheSouthTranseptofthemainchurch,andtheChapterHouse.Thecomplexis composedoflocalwhitesandstone;thedoorissurroundedwithsidepillarsofdark redsandstone(Photograph:MaureenYoung,HistoricEnvironmentScotland).

becauseitcontainsthelargestareaofmediaevalpolychromatic walldecorationinScotland,paintedwithtemperaontolime plas-ter (Fig. 2). However, it has been at risk for some time from water ingress fromabove and high air humidity.Interventions

Fig.2. PartofthemediaevalpaintedceilingintheChapterHouseatDryburghAbbey, ScottishBorders,showingdetailsaroundtheeast-facingwindow.Thesurviving dec-orationisveryfaint.Theimagealsoclearlyillustratesthegreeningofthestonework causedbythebiologicalcolinisation,thatisthesubjectofperiodiccleaning.The debateaboutthecontrolofthissurfacealteration,throughdirectenvironmental controlmeasuresorcleaning,isakeyconservationissueatthesite(Photograph: MaureenYoung,HistoricEnvironmentScotland).

todate have includedre-roofing and waterproofing,as wellas theconstructionofaFrenchdraintoamelioraterisingdamp.The decorationsandtheinternalwallssuffernonethelessfrom coloni-sationbyalgaeand lichens. Theceilingand wallsarecurrently cleanedusingaweakchemicalbiocidaltreatment.This interven-tionis regarded by HSas anacceptable temporarymeasureto controlthebiocolonisation,whichreturnsrequiringbiannual re-application.Otherinterventions,suchasUVirradiationofthewalls, haveproventobeineffective[30].

Morerecentscientificresearchandinterventionhasfocusedon preventativeconservation.Dataloggershavebeenusedto moni-tortheRH(>90%)andthemovementofcondensingair.Basedon thesedata,theintroductionofadoorandwindowglazinghasbeen proposed,allowingactivecontrolofhumiditytodiscourage bio-logicalgrowths.Toexplorethepossibleeffectsofenvironmental modification,HSconductedanexperimentaltrialduring2012–13 ina smallroomadjoiningtheChapterHouse.Thetrial demon-stratedthatrelativehumidity(RH)couldsuccessfullybecontrolled throughthismethod,butpaintingconservators,architectsandsite staffhaveexpressedconcernsregardingthewiderimpactofthe intervention.Theserangefromthepotentialriskofpromotingsalt efflorescenceontheplasteritself,tocompromisingtheatmosphere andauthenticityoftheChapterHouseandtheAbbey.Atthetime ofourresearch,HSwasstillconsideringthebestcourseofaction.

Our researchconsistedof participantobservationat thesite andinterviewswithvisitors,HSsitestaff,aconservationarchitect, paintingconservators,andtheconsultantpreventiveconservator whowascommissionedtolookatenvironmentalconditions. Dif-ferentperspectivesontheconservationproblememerged.From thepointofviewofthepreventiveconservator,‘incorrectrelative humidityisprobablythebiggestwayofacceleratingdecay’,a per-spectivegainedfromstudyingforuniversitydegreesinHeritage Conservation(Bournemouth)andSustainableHeritage(UCL).To hismind,the‘uniqueness’of theplaster justifiesthesignificant architectural interventions proposed to achieve environmental control. His ‘solution’ focuses on the specific problem of bio-colonisation,andtheenvironmentaldatahehadgathered.Wider concerns,includingtheaesthetics,energy,andcostsofthe archi-tectural interventions, were emphasised by other conservation professionalsinvolved.

The painting conservators knew the case well, visiting reg-ularly for biocidal treatment, which theyregard as a tried and testedapproach.In contrast,thepotentialunforeseenimpactof thepreventativemeasuresproposed,inparticularthepossibility ofincreasedsaltformationduetodehumidification,madethem uneasy.Asoneconservatorputit:‘Idon’twanttohaveitallonmy head,doingsomethingsomajoronsuchapreciousthing’.This cau-tion,‘aconservative’approachinherterms,reflectedherinterest inthepaintingsthemselves:‘Ifeellikeit’sabittoopreciousaplace justtodoanexperimentwith,inaway’,shereflected.‘Oftenwe golookingforanswers’,shecommented,‘wetendtothinkthat“if sciencehastoldyou”thenitmustberight.Andinsomecasesitis, butnotalways’.

TheHSarchitectresponsibleforcoordinatingdecision-making atthesitealsoconsideredthescientific resultsasone ofmany factors:‘Ithinkthearchitect’srole’,hesaid‘istogivethewider picture and see whether it fits in with all the other parame-tersonehasonthatspace’.Withinthis frameofreference,the interventionsrequiredfordehumidificationoftheChapterHouse havewidespreadramificationsforthevaluesassociatedwithit, andindeeditsauthenticity.Anenclosedstaircasewouldhaveto beadded,but this, hepointed out,would needtobebased on ‘conjecture’.Furthermore,inhisview,thescientificdataon envi-ronmentalconditionsarea‘snapshot’of‘absoluteconditionsthat areperceivedatonetime’,but‘thetroubleistheymaynotbe typ-icaloftheotherusesthatthespacesget...soIthinktheyalways

havetobeputincontext’.Heenvisagedthata‘cleanand mod-ern’glassboxwouldneedtobebuilt,anarchitecturalintervention clearlydifferentiatingtheinterventionfromtheoriginalfabric.‘But somepeoplewouldhatethat’,hereflected,demonstratingtheway inwhichvariousperspectivesareweighedduringdeliberation:‘A lotofpeopleusethatspaceforweddingsandtheylikethe whole-nessof[it]Ithink;thefactthatithashardlyhadanyinterventionat allsincethe19thcentury’.Asaresult,regularuseofbiocideswas seenaslikelytodoless‘harm’thandehumidification,becauseasa formofinterventionitismuchmorecontainedandhasfarfewer ramificationsforotheraspectsofthebuilding.

Sitestaffandmanagersareperhapsmostfamiliarwith day-to-dayuseoftheChapterHouse.Theyarealsoclosely involvedin itsuseasa weddingvenue,meetingcouplesandmaking book-ings.Theytooemphasisedthespaceasawholeandstressedthat itlookas‘natural’aspossible.Theyenteredintolong conversa-tionswiththeMAVprojectethnographerabouttheimplicationsof thearchitecturalsolutionproposedtocontroltheenvironmental conditions;whatkindofdoorwouldbe‘appropriate’and ‘authen-tic’?;wouldithavehadmetalhinges,andifso,whatkind?They wereconcernedabouthowconservationeffortsfocusedonhow thepaintedplastermightaffecttherevenuegainedthrough wed-dingbookings,andtherebythefutureofthesiteasawhole.‘You can’tputinaglassdoor’,commentedoneseasonalworker,‘unless youhaveaverygoodreason.IfyouclosedofftheChapterHouse, you’dbetakingsomethingawayfromtheAbbey–thefreedomto justgoin’.Forhim,this‘freedom’allowedvisitorstoexperience ‘howitmighthavebeen’,andalsogavehimjobsatisfaction:‘It’s thebestbitofmyjob,goinginfirstthinginthemorning’.

Informalinterviewswithvisitorsthemselvesgatheredarangeof viewsonthepossibleintervention,themajorityofwhich referen-cedtheruin’smaturewoodedsettingandthe‘romantic’aestheticof thesite.TouristsmovingbetweentheAbbeysoftheborderregion expressedpositiveorientationstodecay as‘natural’,sometimes connectingthistobiologicalunderstandingsoflife.Oneexpressed adesireforDryburghto‘havedeathinbeauty’,andanotherwasfor itto‘beabletodecayslowly,withoutuspreventingit’.Biological growthinmostareasoftheAbbeywasappreciatedaesthetically: pointingtogrowthontheruin’swalls,onecouplepointedoutthat ‘it[thewallandfoliage]hasbeenthereforhundredsofyearsandI think[...]weshouldkeepthat’.

The Dryburgh case study reveals a wide range of concerns abouttheproposedscience-basedinterventionsandtheirimpact onwider values.It shows thatdifferent formsof expertiseand theframesof referenceassociatedwiththem producedifferent kindsofvaluation,whichrelatetodifferentideasaboutwhatis ‘real’or‘authentic’,andhenceimportant,aboutthesite.Inthe sci-entificmeasurementofenvironmentalconditionsassociatedwith thebiocolonisationofthepaintedplaster,theenvironmental con-servatorextractscertainmaterialsandvariablesfromthewider concernsofotherheritageprofessionals.Attemptingtoreinstate widerrelationships,monumentstaff,architectsandpainting con-servatorsworkthroughthewiderramificationsoftheproposed architecturalinterventionsnotonlyfortheauthenticityandvalue ofthepaintedplasteritself,butalsotheChapterHouseandthe Abbeyasawhole.Inassemblingthesewiderrelationships,they drawondifferentformsofskilledvision,buttheyalsoinvoke vis-itorperspectivesandexperiencesassociatedwiththenotionofa romanticruinanditsaestheticvalue,particularlyasthisappealsto theweddingmarket.

ThepreservationofDryburghAbbeyasaromanticruinis asso-ciated by conservation professionals and visitors with distinct but overlapping understandings of aestheticvalue,historic sig-nificance andauthenticity.These areassociatedwitha rangeof context-specific assessmentsof howheritage scienceis applied and whetherthesolutions associated withit areimplemented.

Fig.3. SkelmorlieAisle,Largs,EastAyrshire(1636–38),istheremainingfragment ofalarger,nowdemolished,church.Itnowsitsinagraveyardinthecentreof Largs,enclosedbythesurroundingwallandotherbuildings.Itshighlightliesinside, thedramaticallycarved17thCloftandmausoleumoftheMontgomerieFamily (Photograph:MaureenYoung,HistoricEnvironmentScotland).

Furthermore,thecaseshowshowspecificformsofvaluationare negotiatedthroughthelensofdifferentkindsofexpertise.The atti-tudes,valuesandexpectationsof‘thepublic’arealsoimportantin thisprocess,frequentlyprojectedbyprofessionalsaspartoftheir valuationsanddebates.Scientificevidenceisvaluedinitselfasa justificationforaction,butthetendencytoextractdatainrelation toaspecificproblem,akindof‘snapshot’inthewordsofthe conser-vationarchitect,isviewedwithcaution.Finally,itisevidentfrom thedatapresentedthatwhiletheprofessionalsinvolvedbringtheir ownexpertiseandevaluationstothecase,decision-makingtakes placeinaninstitutionalcontext,wherethedifferentauthoritiesof theparticipantsshapetheevaluationsinvolved.

5.2. SkelmorlieAisle,Largs,NorthAyrshire

OursecondcasestudyfocusesonSkelmorlieAisle,wherestone decayisattributedlittlevalueintermsofpatinaandthe authentic-ityofage.Insteaditisseenasmalignifpoorlyunderstood,andits influenceneedstobearrested.Yet,asweshow,material authen-ticityisstillprivilegedandheritagescienceisbeingdeployedto trytounderstandthematerialprocessesatworkandthe environ-mentalconditionsinformingthem.Thecaseallowsustoexplore thedistinct,yetrelational,valuesassociatedwithdifferentkindsof heritagescience.

SkelmorlieAisle(Fig.3)inLargs,NorthAyrshire,wasbuiltinthe 1630sbySirRobertMontgomerieofSkelmorlietoprovideaplace forprivateworshipandburial.OriginallythenorthtranseptofLargs oldchurch,itremainedasafree-standingmausoleumstructurein thehistoricgraveyardaftertherestofthechurchwasdemolished in1802.TheloftoftheMontgomerietombwithintheAisle com-prisesarichlycarvedrenaissancestylecanopy,indensepalegold sandstone,whichisraisedoverapartiallysunkburialvaultand approachedbystepswithabalustradedparapet(Fig.4).TheAisle itselfhasawoodenbarrel-vaultedceiling,paintedwithquotesfrom theGenevaBibleandrichallegoricallandscapesbyJamesStalker, datingfrom1638([31]:Fig.5).Togetherthecarvedstone tomb canopyandthepaintedwoodenceilingrepresentperhapsthemost outstandingexamplesofsuchworkinScotland.TheAisleisboth ascheduledancientmonumentandaHistoricScotland(HS) Prop-ertyinCare.Nevertheless,visitornumbersareconsiderablylower thanDryburgh,inpartbecauseaccessismorerestricted.Keysfor thegraveyardandtheAislemustbeobtainedfromLargsMuseum

(open2–5pmbetweenMayandSeptember).

Fig.4.TheinterioroftheSkelmorlieAisle.Therichlycarvedrenaissancecanopysits abovethesubterraneanburialvaultoftheMontgomeries.Thecanopy,orloftwas theprivateworshipspaceoftheMontgomeries.Thewoodenceilingabovetheloft isrichlyillustrated(1638)withallegoricalclassical,biblicalandlandscapescenes, includingoneofLargswiththefullchurchwiththeAisleitself,beforedemolition (Photograph:MaureenYoung,HistoricEnvironmentScotland).

Fig.5.DecayonthetopofthetombattheSkelmorlieAisle,Largs.Herethedense fine-grainedsandstoneissufferingfromcrateringandpowdering.Atthecentre toprightoftheimage,anenvironmentalloggingdevicecanbeseenattachedto thestructure,recordingconditionsofTemperatureandRelativeHumiditynearto wherethedamageisoccurring(Photograph:MaureenYoung,HistoricEnvironment Scotland).

Theceilingpaintingsareina goodstateofpreservation.The tombcanopyisfaringlesswell.Althoughtheupperstoneworkis crisp,thelowerpartsappearbadlydecayed.Granular disintegra-tionandexfoliation(Fig.5)havebeenevidentsincethemid20th century,manifestingascraters,flakingandpowderingonthe sur-face.Indeed,recordsshowthatin1940powderedsurfaceswere treatedwithMagnesiumFluorosilicatewithlittleevidentsuccess. Inplaces,athincrusthasformed,withdisintegrationcontinuing beneath.Sofar,thedecayhasbeenattributedtohighmoisture lev-elsandpossiblesaltcontamination.Therearealsodamppatches andsalt efflorescenceonthewallsof theAisle,whichare con-structedfromcourseashlar.Thesouthwallisaparticularconcern, becauseitoriginallyconsistedofaninternalwallwithapointed archthatwasblockedandrendered(‘harled’inScotland)externally aftertherestofthechurchwasdemolished.

Atthetimeofthisproject,HShadbeeninvestigatingthestone decayforfiveyears, drawingontheexpertiseoftwo conserva-tors(onestoneconservatorandonepreventativeconservator)and twoheritagescientists (bothwithgeologicaltraining).Moisture mappingofthetombanditscanopyusingmicrowavesensorsand thermography showedno clearpattern related torising damp. Petrographicanalysisofthestonerevealedittobeverydense– confoundingexpectationsthatdecaymightbeassociatedwithhigh porosityandlowstrength.XRDanalysiswasappliedtosalt efflo-rescencetoexplorepollutantsandthepresenceofdifferentsalt types.Basedontheseresults,itisapparentthatthestonedecay isnotdirectlyrelatedtotheeffectsofmoistureorsalts.The her-itagescientistsinvolvedhavealsoconsideredthepossibilitythat condensationeventsaredestabilisingpyriticinclusions,producing sulphuricacid,whichisthendissolvingcalciumandiron carbon-ateinthestone.Aspartofthecurrentresearch,temperatureand humidityintheAislehavebeenmonitoredusingdataloggers.

Therootcauseofthestonedecayonthesurfaceofthetomb structureremainsapuzzle.Theisolatedcharacterofthedecay,and themannerinwhichiteludesacleardiagnosis,places conserva-torsinlong-termdialoguewithmaterialscientists,geologistsand preventiveconservators.Effortstofindoutwhathasbeencausing theflakingofthestonedemonstratehowdifferentprofessionals engagewithmaterialtransformationindifferentways.

Thematerialsscientistsfocusdirectlyontheprocessof mate-rialtransformationtakingplace,extractingtheproblemfromits widerhistoriccontextandassociatedvalues.Oneofthemexplains: “If you canfindout what’scausing the decayand stop it hap-pening,that’snotgoingtochangeitscurrentvalue,it’sgoingto preventlossofvalueinthefuture”.Thepursuitofknowledgeand understandingalsoprivilegescertainkindsofanalyticaltechnique relatedtothematerialitself;inthiscase,whilstthedecayed pow-deredstoneisuseful,coresamplesarepreferred.However,such destructivesamplingwouldrequireconsentfromheritage man-agerswithinHSandarousesanxieties.Asthestoneconservator putit:‘ifyoudon’tknowwhatmaterialyou’redealingwithyou don’tknowhowyou’regoingtotreatit’,butsamplingis ‘destruc-tive’,andhaslimits.‘Itwilltellussomethingaboutthepetrography ofthematerialandthestructureofitanditscontents’,shenoted, ‘butitdoesn’tnecessarilytellusanawfullotaboutthebehavioural properties’,whichareparticularlyrelevanttounderstandingthe processofdecay.Furthermore,mobilisingvaluessurroundingthe authentichistoricmaterialincontrasttoscientificvalues,youcould endupwithmonumentsthat‘looklikewaspsnests;you’vegot nostoneleft,you’redoingfarmoredamagethanyoucanpossibly dogood’.

The issueof samplinghighlights the values associated with heritage scienceitself, aswellas withmaterial transformation.

There are also concerns about the unknown consequences of

science-basedinterventionsespeciallythoseassociatedwithnew materials,asthestoneconservatorcommented:

Weareveryreluctanttodothingsinvolvingapplyingchemicals unnecessarily.Especiallythingsthatareirreversible,ifwedon’t understandthelongtermeffectswellenough.Therearesomany examplesinthepastthathaveturnedoutbadlythatwerewell intentionedatthetime.

YettheroleofheritagescienceintheUKhasincreased.Thestone conservator again highlighting the complex interplay between experience,judgementandevidence,said:‘Inthepast,[wehadthe attitude],it’salwaysworkedbeforewhywouldn’titworknow? Nowit’smuchmore“Well,haveyougotthescientificevidence, andwhatdoesthattellus”?’Theproblemisthattheevidence,in thisandmanyothercases,isfarfromincontrovertible.

Hypotheses aboutthemechanisms of decayat workon the

Mausoleumemergedfrom–andweredisprovedby–techniques, suchasmicrowavesurveys,thermalsurveys,orbuildingsurveys. Intheirturn,theyraisedthepossibilityofinterventionsthatcould leadtofurthermaterialtransformation,asinthecaseofthe Dry-burgh Chapter House.An earlyhypothesis was that salts were beingdrawninfromthegroundthroughthecryptwallsupinto themonument.Thestoneconservatornotedthattheinterventions requiredtoalleviateitwouldbe,inherterms,‘veryinvolved’.New drainsandadampproofmembrane,possiblyeven‘disturbingthe archaeology’,wouldrequiresupportfromtheHSarchitectand her-itagemanager,somethingserioussheassociatedwithjustifications andpermissions.Inherview,scientificresearchprovidedleverage withotherprofessionalsintheprocesswhocouldauthorise deci-sionsandstrategies.Theheritagescientistworkingcloselywithher agreed:‘it’sthecoreof[the]decision:otherwiseyoudon’thave anythingtodiscuss–aproblemwithoutasolution’.

Asaresultofthisdesireforevidence,scientificanalysiswas broughtintotheprojectinarangeofotherwaysbeyond samp-ling.Onekeydatasetwascollectedbytheenvironmentaldata loggersmonitoringtheinternalenvironmentinwhichthe memo-rialstands.Thiswasthedomainofthepreventiveconservators, whohave,asatDryburgh,proposedenvironmentalmodification toavoidcondensationevents.Temporarylow-levelheatinganda blindagainstsolargainhavebeenintroducedtoassesstheeffect ontheenvironment,essentiallytoinvestigatewhetherreducing thehumidityandstabilisingthetemperaturewilldiminishdecay. However,thisinturnraisesconcernsforthearchitectaboutthe impactonthewallsoftheAisleitself;woulddryingoutthe inte-riorsimplydrawmoremoistureinthroughthewallsandincrease salt efflorescence onthem?And heasked, what ofthe unfore-seenimpactontheceilingpaintings?Relativesignificancebased onarangeofvaluesisthusbroughttobearonpotentialsolutions totheparticularareaofmaterialtransformationsubjectto scien-tificresearch.ThecarvedMausoleumstructureisgenerallygiven greatervalue,thanthewallsifnottheceilingpainting.Yetthe impactofinterventionsorientedtotheformeronthelatterstill requiresevaluationandjudgement.

UnderstandingsofthespecificsignificanceofSkelmorlierelate tocontext-specificevaluationsoftheproblemsandpossibilities associatedwithvariousformsofscientificunderstandingand inter-vention.IncontrasttoDryburgh,aromanticruin,theconservation teamdonotdeemthematerialprocessesatwork,inthiscasesalt efflorescence,peelingcrustsandstonedecay,topossessaesthetic meritor‘agevalue’,eitherfromtheirownperspectivesorthose theyprojectontovariouspublics.Instead,decayofthetombcanopy isunderstoodasaprobleminthefunctionofthebuildingthatneeds toberesolvedtopreservetheelaboratecarving.Ideasabout pub-licvaluesfigurelessprominentlyinnegotiationsatSkelmorlie,but theyarestillimplicated.Asthecurrentpreventativeconservator observed,an‘ideal’environmentwould beamuseumwhere all environmentalfactorscouldbecontrolled,butthiswouldnotbe an‘ethical’decision,sinceitconflictedwiththevaluesplacedon

Fig.6.Thewestfac¸adeandtheentrancetotheHillHouse,Helensburgh,Argylland Bute(C.R.Mackintosh,architect,1904–5).Thisviewwastakenin2013somemonths aftertheexteriorPortlandCementrenderhadbeenpaintedtounifytheappearance andimproveresistancetoenvironmentalattack.TheClydeestuarycanbeseenin thebackground(Photograph:JohnHughes).

publicaccess,somethingthatthearchitectandheritagemanager confirmed.Finally,weobserveagainthatconservationand mate-rialscientists workinanarenawherepermissions,jurisdictions anddifferentperspectivesonthenatureofaconservation prob-lemco-exist.Inthiscase,itisthevaluesassociatedwithheritage scienceitself,andthetensionsthatcanarisebetweenscienceand conservation,whicharebroughtintosharpfocus.

5.3. TheHillHouse,Helensburgh,ArgyllandBute

OurfinalcasestudyisHillHouse,anexampleofthekindof modernistarchitecture,whichisanincreasingconcernforheritage organisations.Itpresentsaspecificsetofconservationissues relat-ingtothedistinctivematerialsused,andtheextenttowhich a monument-derivedconservationphilosophyof‘minimum inter-vention’ is an appropriate response. As we show, these issues impactontheapplicationofheritagescience,inacontextwhere ‘authenticity’islessamatterofmaterialoriginalityandmore com-monlyassociatedwithaspecificarchitecturalvision.

TheHillHouse(Fig.6)sitsonanelevated,exposed, southwest-facingcoastalsiteabovethetownofHelensburgh,approximately 30kmwestofGlasgow.Designedandconstructedduring1903–4

by the Glasgow-based architect Charles Rennie Mackintosh

(1868–1928),itwascommissionedbyScottishpublisherWalter Blackie,ashisfamilyhome.Mackintoshwasamodernarchitect withadistinctivestylevariouslyassociatedwiththeArtsandCrafts, ArtNouveau and European secessionistmovements. Heis also knownfordesignandfurnishingoftheinteriorofhisbuildings,in partnershipwithhiswifeMargaretMacdonald,aswasthecaseat HillHouse.Mackintosh’sstatushasincreasedsignificantlyinrecent decades,meaningthathissurvivingworknowattractsthehighest levelsofstatutoryprotection.TheHillHousewasdesignateda Cat-egoryAListedBuildingin1971anddonatedtotheNationalTrust forScotland(NTS)in1982.Ithasaresidentpropertymanager,and isopentothepublicbetweenAprilandOctober.

Mackintoshwaskeentoapplynewmaterialsinhisbuildings. WhilsttheHillHousehassolidmasonrywallsmadefrombrick andsoftredsandstone,theexteriorisrenderedingrey-coloured roughcastrender,or“harl”,containingPortlandCement(PC).Atthe time,PChadgainedcurrencyandwaspromotedasthestrongest, most waterproof material available [32]. This claim persuaded

Fig.7. ExampleofthecrackinginthePortlandCementrenderoftheHillHouse, Helensburgh.Crackingsuchasthisallowswateringressthatthreatensthehistoric Macintosh-Macdonalddesignedinteriordecorationandfurniture (Photograph: JohnHughes).

Mackintoshtouseitinhispursuitofnovel,moderndesignvalues, allowing him todispense withtraditional water-shedding fea-tures,suchaswallcopesatgablesandwindowcills.However,the inflexibilityofthePC-basedrender,comparedwithalime-based alternative,hasresultedin extensivecracking (Fig.7).PC’s low waterpermeabilityandhighcapillaryretentiontrapsanywater ingressthatoccursthroughthecrackscausingfurther deteriora-tionoftherender,exacerbatedbyfreeze-thawaction.Inplaces, moisturehaspenetratedthewholewall,puttingthe Mackintosh-Macdonaldinterior at risk by increasingRH and condensation, resultinginmouldgrowth.Therehavealsobeenoutbreaksofdry rot.Recentscientificinvestigationshavefocusedoninvestigating theconditionofthefabricofthebuildingusingmaterialsanalysis (petrographicthinsectionsandXRD)andthermography,alongside traditionalengineeringandconditionsurveying.Theinternal envi-ronmentisbeingmonitoredwithHanwellrecordersdocumenting temperatureandRHinseveralrooms.

TheNTSareintheprocessofexaminingthehistoryofrepairs andthescopeofpossiblefutureinterventions([32]).Their deliber-ationscentreonthestatusoftherender,particularlytheextentof originalfabricremaining,andthetechnicalrepairchallengesposed bypreviousinterventions.In terms ofconservationphilosophy, therearequestionsregardingauthenticityandwhetherthis lies intheoriginalfabric,orintheotheraspects,suchasthebuilding’s designandMackintosh’sintentions.Duringthe1980s,a hydropho-bicsilanewasusedwithlimitedsuccess,bothasasurfacewater repellentcoatingandasaconsolidantinconjunctionwithcarbon rodties intheinterfacebetweenthePCharlandthedegrading underlyingsandstone([32]: section3.1).Currentthinking ques-tionsthe appropriateness of this former conservation strategy, sinceitusedanirreversibleexperimentalapproachtopreservethe fabricthroughintroductionofadifferentmanufacturedmaterial ([32]:75).Therearealsoconcernsaboutwhethertheuseofthe silaneconsolidanthasexacerbatedproblemswiththeharl, lead-ingtofurtherproblemsofwaterretention.Evidencenowsuggests thataconsiderableamountoftheoriginalrenderhadinfactalready beenreplacedduringtheHillHouse’slifecycle,perhapsasmuch as80%.

Thesediscoveriesalsocomeattimewhen conservation atti-tudestowardstwentieth-centurybuildingsandmodernmaterials arechanging,notleastasaresultoftheMadridDocument[33].As theregionalLeadSurveyorontheNTSBuildingsTeamcommented duringaprojectinterview,thekindsofproblemsfacedbytheHill Houseare

aninternationalissue,andthat’stherightsortoflevelthatthese debatesreallyneedtohappen...tofaceuptothefactthatthere maybehastobea slightlydifferentapproach insomecases, whenitcomesto20th_{Centurybuildings,youknow,theycan’t} allbetreatedlikeDryburghAbbeywhereeverysinglestonehas tostayinexactlythesameplaceforeveryouknow.[...]Material hastofunction.

ThefigureofanimportanthistoricarchitectlinkedtoHillHouse isalsoadistinguishingfactor,whichmeansthatmaterial transfor-mationissubjecttoadifferentsetofvaluations.‘Tobeconsistent withtheMackintoshdesignintention’,heremarked‘youhaveto tryandmaintainsomethingthat’slookingquitecrispandsharp’. Inthelightofthis,solutionsarebeingsoughtthataimtopreserve themodernsilhouetteand‘unityofstyle’inlinewithMackintosh’s architecturalvision,evenifthatmeanssacrificingorreplacingthe PCrender.Indeed,Wright([32]:94)remarksthat‘perhapstheHill House‘unityofstyle’mightbeconsideredastheprimaryvalueto bepreserved’(originalemphasis).Here,then,aestheticand archi-tecturalvaluesareprivilegedoverauthenticityofmaterials,with authenticitybeingrelocatedinrelationtoMackintosh’svision.

Aesthetic values and Mackintosh’s intentions also feature heavilyindataonvisitorexperiencesandguideperspectives. Vol-unteerguides regularlysharetheirknowledgeofthehouseand itshistorywithvisitors.Duringinterviews,theyreportedfeeling underpressurefromvisitorswhoseonlyexperienceofMackintosh hadbeenthroughglossycoffee-tablebooks.Visitorswere some-timesdisappointedorangeredbypeelingpaint,discolouration,or visiblecracksintheexternalharlofthehouse.Havingcomewith expectationsregardingthe‘modernity’ofMackintosh’swork,signs ofageareconsidered‘inappropriate’bymany.Asonematerials sci-entist,withextensiveexperienceofbuildingconservationaswell assampleanalysis,noted

[visitorsoften] wantto seewhat Mackintoshperceived and what he delivered,because that’swhat they’vebeen ledto expect.Sowhentheyseedecay,theyseediscolouration,they seetheeffectsofwaterpenetration,thefirstresponseis“nobody islookingafterthis”.

TheHillHousecasestudyprovidesanaptcontrasttotheother casestudies,reinforcingourargumentthatvaluesassociatedwith material transformation are context-dependent and emerge in relationtospecificbuildingsandmonuments.AtHillHouse,signs ofmaterialtransformationandagevalueconflictwiththeaesthetic modernityofitsdesignformanyheritageprofessionalsandindeed visitors.Asaconsequence,formany,conservationofthedesignof thebuildingisdeemedmoreimportantthanpreservationofthe originalPCrender;materialauthenticityisthusdisplaced.Project interviewsexploredthecontextualmeaningsof‘authenticity’and ‘truthfulness’,revealingthatdifferingunderstandingsofthese con-ceptsinformdistinctapproaches.Volunteerstaffwhoworkedat theHillHouse,forexample,wereconcernedwithpreservingthe appearanceofthebuilding,withlessconcernforthe‘authenticmix’ ofPortlandCement.Severalstaffremarkedthatrecentpaintingand repairoftherendercompromisesauthenticity.Intheirviewa full-scalereplacementwouldbetter‘servetheinterestsofhouseandthe public’byreplacinga‘failedexperiment’withamaterialthatwould withstandthedrivenrainoftheHillHouse’sexposedposition.

TheHillHousealsohighlightshowthehistoryofabuildingand itspreviousinterventions,aswellashistoricalshiftsin conserva-tionpriorities,informsvaluesandactionsinthepresent[34,35]. ThevalueassignedtothematerialfabricoftheHillHouse ren-der hasshiftedover time. In previousconservation campaigns, the values associated with what was thought to be the origi-nalfabricjustifiedexperimentalinterventiontokeepitinplace. Subsequently,thesevaluationshavebeenquestioned,anddoubts

raisedabouttheoriginalityofthefabric.HillHousealso demon-strateshowconservationinterventionsareincreasinglyrequired to take account of previous treatments, whose behaviour was notanticipatedandmaynotbepredictable[3].Thisencourages cautionamongstconservationprofessionalstowardsnew scientif-icallydevelopedproductsastheyareexposedtothedetrimental effectsofwell-intentionedhistoricalinterventions.Finally,theHill Housecaserevealshowthescopeofscientificintervention–as a problem-solvingactivity–maybedeterminedinadvance,by otherformulationsofwhattheproblemis.Prioritieslike“preserve theoriginalfabric”or“preservetheartisticvisionofthearchitect” definetheparameters(andgoals)ofscientificresearch,andthe likelyacceptabilityofsolutions.

6. Conclusions:implicationsandrecommendations

At the outset of this article, we argued that if the aim of conservationistosustainand shapethevaluesassociated with heritageobjects,thereisaneedforgreaterattentiontothe relation-shipbetweenmaterialtransformation,value,andheritagescience. Indeed,radicalchangesinhowsignificanceandauthenticityare conceivedin conservationphilosophy,withincreasingattention tointangibleaspectsofheritage,havecreatedapressingneedfor newresearchontheroleofmateriality[17,18,21].Yet,inmany areasofheritagepractice,theconservationofmaterialfabricand theconsiderationofsignificance,valueandauthenticityproceed inaparallel,atbestlooselyconnectedfashion.TheUKHouseof LordsScienceandTechnologyCommittee’sReportonScienceand Heritage[2]isagoodexample.TheReportvociferouslyadvocates thedevelopmentandapplicationofheritagescience,but,although itdefinesconservationintermsofsustainingthevaluesassociated withheritage([2]:11–12),muchofitsfocusisonpreserving mate-rialfabric.Consequently,thereislittleattentiontotheimportant questionofhowtheapplicationofscienceintersectswithvalues.In recentwork,Cassar([26]:9)hasemphasisedthe‘symbiotic’ rela-tionshipbetweenmaterialtransformation,interventionandvalue, andcalledforadeeperunderstandingofwhatshecallsthe ‘mate-rial/cultural’ interface.We endorsethis call,but we argue that attemptstoquantify,categorise,orsystematisethisrelationship (e.g.[34,36])areinevitablylimitedtogeneralizationsthatskate thesurfaceofthecomplexdynamicsinvolved.

Our interdisciplinary researchreveals that values associated with material transformation emerge in particular contexts, informedbydifferingconstellationsofmaterials,processes, prac-tices,visitorexpectations,usepatterns,buildingtypesandforms of expertise. In some contexts (Dryburgh Abbey), weathering and decaycan accrue ‘agevalue’,markingthepassageof time, contributingtotheexperienceofauthenticity,andcreating aes-thetically pleasing ‘character’, ‘patina’ and ‘ruination’. In other cases,materialtransformationanddecayareassociatedwithaloss ofvalueandauthenticity,eitherdirectlythroughlossofmaterial itself(SkelmorlieAisle),orbecauseofthewiderimplicationsof deteriorationinpartofthehistoricfabricfortheauthenticityand valueofthemonumentorbuildingasawhole(TheHillHouse). Justasthevaluesassociatedwithmaterialtransformationemerge inparticularcontexts,sodoestheapplicationofheritagescience tounderstanding,controllingandarrestingmaterial transforma-tion.Itisnotjustacaseofidentifyingpre-existingvaluesthatthen informhow‘problems’areframed,andwhenandhowheritage scienceisapplied.Rather,theapplicationofscienceinheritage contextsisembeddedindynamicmodesofvaluation.Theuseof scientific techniquestomeasure,understandand control mate-rial transformation is informedby thesevalues, but thesevery processesalsohavethepotentialtochangethosevalues.Asone materialsscientistputit,“thereisn’tageneralisation.Everythingis

uniqueinbuildings”.Hewasreferringtocombinationsofmaterials, craftsmanship,weatheringcycles,locationandclimate,whichare alwaysspecifictoparticularsituations.Inthesameway,thevalues associatedwithmaterialtransformationarenotonlyhistorically specific[19],butalsocontext-dependent,affectedby–amongst otherthings–thenatureofthemonument,thematerialsinvolved, attitudestowardsrisk,modesofexpertise,changingconservation philosophy,institutionalprioritiesandexpectations.

Theimplicationsofthisresearchcanbesummarisedasfollows. First,materialtransformation, includingdecay,doesnot merely impactonheritagesignificance.Itisanintegralaspectofthevalues thatunderpinsignificance.Second,thesevaluesaredynamicand contextual.Theymayvaryovertime,betweenandwithinsites,and betweendifferentheritageprofessionalsandstakeholders,inways thatcannotbedeterminedinadvance.Third,theapplicationof her-itagesciencetomeasuring,understandingandmodifyingmaterial transformationisembeddedinthesevalues;itbothinformsand isinformedbythem.Fourth,integratedqualitativeresearch meth-odscanincreaseourunderstandingoftheseimportant,site-specific conditionsandprocesses,andthuscontributetomorenuancedand productiveapplicationsofheritagescience,sensitivetothevalues associatedwithheritagesites.

Inlightofthesepoints,werecommendthatfurtherqualitative researchisconductedontherelationshipbetweenmaterial trans-formation,authenticity,valueandheritagescience.Thetendency ofheritagesciencetofocusonaspecificmaterialor environmen-talprocess and toextract data in relationto this, even setting upcontrolledlaboratoryexperiments,meansthatCassar’s([26]: 9)‘material/culturalinterface’isalwaysindangerofbeing over-lookedandthisrequiresfurtherattention.Importantly,however, itwillnotbepossibletoidentifyrulesormodelsthatcanbe gen-eralised,becausethevaluesandqualitiesassociatedwithmaterial transformationarecomplex,situatedandcontextual.We there-fore recommend that qualitative methods, such as participant observation,interviewingand focusgroups,shouldberoutinely employedtoexplorethesite-specific valuesand qualities asso-ciated with material transformation. Data from such research couldthen betaken into account when planninginterventions andassessingtheirfutureimpact.Changesintraining,expertise andinstitutionalcultureswillalsobenecessarytoeffectively inte-grate qualitative methods in such a routine fashion. Therefore, ourfinalrecommendationisthatforumsarecreatedtofacilitate open-endeddiscussionofsuchissuesamongstheritagescientists, conservators,managersand otherheritage professionals.Whilst ithaslongbeenrecognisedthat cross-disciplinarycollaboration iscrucialinheritagemanagementandconservation,the promo-tionofinter-disciplinarydialogue,especiallyacrossthesciences andhumanities,is alesscommonplace,butincreasingly impor-tantmeasure.Combinedwithsuchevents,furtherinterdisciplinary researchofthekindcentraltotheMAVproject,involvingpersonnel withbothscientificandhumanitiesbackgroundswillhelpbuilda workingenvironmentwherethereisamoreholisticconsideration oftheculturalramifications ofscientific interventionsalongside theirmaterialeffects.

Acknowledgements

ThearticleisbasedonresearchconductedfortheAHRC/EPSRC Science and Heritage Programme Project Materiality, Authen-ticity and Value in the Historic Environment: a study of the effects of material transformation and scientific intervention (AH/K006002/1).Italsodrawsonresearchconductedforthe Enact-ingConservation:theroleoftechnology,scientificexpertiseand evidencein producingthepastproject,partfundedbyaBritish Academy/LeverhulmeSmallGrant(SG122587).Wearegratefulto ourprojectpartners,HistoricScotland(nowHistoricEnvironment

Scotland)andtheNationalTrustforScotland.Participantsinour projectworkshopcontributedtothedevelopmentofthearguments presentedinthisarticle.Finally,wewouldliketothankstaffatour casestudysitesandourresearchparticipants,withouttheirtime andgenerositytheresearchwouldnothavebeenpossible.Grateful thanksareextendedtoDrMaureenYoung(HistoricEnvironment Scotland)forthephotographsusedinFigs1–5.

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