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1、bs_bs_bannerArchaeometry54,5(2012)906–915doi:10.1111/j.1475-4754.2011.00657.xPOROSITYDETERMINATIONWITHHELIUMPYCNOMETRYASAMETHODTOCHARACTERIZEWATERLOGGEDWOODSANDTHEEFFICACYOFTHECONSERVATIONTREATMENTS*I.D.DONATOandG.LAZZARADipartimentodiChimicaStanislaoCannizzaro,UniversitàdegliStudidiP
2、alermo,VialedelleScienzeEdificio17,90128Palermo,ItalyTheheliumpycnometerallowsustomeasurethecell-walldensityofdrywoodsandthebasicdensityofwoodsamplessoakedwithwaterand/oraconsolidantsolutionifanon-volatilesolventisused.Theseparameterswerecorrelatedtotheporosity,whichfordegradedwater-lo
3、ggedwoodisrelatedtothemaximumwatercontent.Moreover,thishasrevealedthepossibilityofinvestigating,bymeansofaccuratecell-walldensitydetermination,theefficacyofseveralconsolidantsinthetreatmentofwaterloggedwoods.KEYWORDS:HELIUMPYCNOMETRY,POROSITY,DENSITY,WATERLOGGEDWOOD,CONSOLIDATIONINTROD
4、UCTIONManypropertiesofarchaeologicalwood,particularlythoseinvolvingdeterioration,sorption,penetrability,swellingandstrain-relatedphenomena,areprobablydependentontheporosityofthewood,which,inturn,dependsoncell-wallandbasicdensities(Caprettietal.2008).Thus,accuratemeasurementsofthesephy
5、sicalparametersareessentialforacorrectdeterminationofsuchproperties.Severalconventionalmethodshavebeensuccessfullyappliedfordeterminationofthephysicalandchemicalpropertiesofwaterloggedarchaeologicalwoods(Caprettietal.2008;Pizzoetal.2010).Theconceptofdensityisverysimple,andthemassandvo
6、lumeofabodywouldseemtobeamongtheeasiestphysicalparameterstomeasure.Actually,foraporous,hygroscopic,polymericmaterial,themeasurementofthevolumeisextremelycontroversial.Thisisparticularlytrueinthedeterminationofbasicandcell-walldensitiesofwood.Fordetermina-tionofthebasicdensity,thevolum
7、eismeasuredbyeitheroftwotechniques.Thevolumeofsampleswithapropergeometricalshapeisobtainedfromthecharacteristicdimensionsmeasuredbymeansofacalliper,whereasforsampleswithanirregularshape,thevolumeisobtainedbymeansofaRegnaultpycnometer,employingmercuryasareferenceliquid.Themeasureofthec
8、ell-w
