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1、Chapter7Internalsizingofpaperbeinganammoniumthiocyanatesolution,andthespecimenbeingpaintedlightlyonthetopsidewithaferricchloridesolution.Thetimerequiredisnotedforthethiocyanateandferricchloridetomakecontactandreact,formingadeepredferricthiocyanate.Thetestdoesn
2、otdistinguishdifferencesathighersizinglevels23.Ahybridofthismethodandthedryindicatormethod,developedbyNeimo10atKCL,utilizingasimplepenetrometerwithaglasswindowontopofthespecimentodetecttheendpointmoredistinctly(e.g.,Williamspenetrometer,Penescope,etc.)yieldssa
3、tisfactoryresultsalsoforrelativelyhard-sizedpaper.LacticAcid(Penescope)Test24,36.Forhard-sizedboardssuchasthoseusedinfoodcontainers,itiscommonpracticetotestsizingintheso-calledPenescopeapparatus,using20%lacticacidsolutionat20°Caspenetrant.Theoutsidefaceofthesa
4、mpleiscoatedlightlywithapH-sensitivedye,e.g.,MethylOrangeorBromcresolPurpleusedasindicator.7.3.1.2MeasurementofliquidabsorptionIntheliterature,testsassignedtothiscategoryareinsomecasesconsideredtobelongtothegrouprelatedtorelationshipsbetweensizingandsurfacepro
5、pertiesofapaper.Cobbtest36,37.Thismethod,essentiallyunchangedsincefirstdescribedmorethan60yearsago,isprobablyoneofthemostwidelyusedtestsinpapermaking.Onesurfaceofthetestsampleisexposedunderagivenhydrostaticheadtowater(oranotherappropriatetestliquid)foraspecifi
6、edtime,usuallyfrom30stoeven10mindependinguponthebasisweightandpossiblyotherspecificationsissuedforthetypeofpaperorboardsubjectedtotesting;forthemajorityofpapergrades,thetesttimeis60sandthecircularareaofthesample100cm2.Attheendofthetest,thewaterisdecanted,exces
7、swaterblottedoff,andtheamountofwaterabsorbeddeterminedbytheweightgain,reportedasg/m2.Theprincipaldrawbacksofthemethodareitsinsensitivitywhenappliedtoeitherhard-sizedorveryslightlysizedpaperorboard,inapplicabilitytothinorabsorbentpapers,lackofcorrelationwithpen
8、etration-typetests,andtherequirementforconstantattentionduringthetest10,24.Themethodisbestsuitedformedium-sizedgradeswith60sCobb-valuesrangingfrom25to50g/m2.Advantagesareflexibilit
