solvent free osmosis treatment

8/8/2019 Solvent Free Osmosis Treatment

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Osmosis, Gelshield PLUJand Associated ProductsSince he introduction f GRPvessels nto hemarketplace s longago as the mid 1960's t hasbeenclearly emonstratedhat fibreglass oatsare not themaintenance-freeesselsheywere once claimed o be,Time and use akes ts oll and he appearance f yachtsgradually eteriorates.Osmosis'has or some ime beena recognisedproblemaffectinga certainpercentageofboats.The best way to preventosmosis n a yacht is toseparate t from water.Thiscan easi! be achievedwith he use of Gelshield poxycoatingsapplied o theundenvater reaof the hull.Gelshield poxy educes helevelof waterpenetrationnto he hull,which s the keyto success n combating smosis.

Genetal Symptomsand Causes of OsmosisPolyesteresin s used n the lamination f most'GRP/FRP'yachts.This resin,which comes n the formof a viscous iquid, s manufactured y the reaction f apolyfunctionalcidwith a polyhydric lcohol.A linkingreaction akesplace n which he watergeneratedn thereaction f the basic ngredients as o be removed.To urn his ntoa solid, he boat builderaddsperoxide,which acts as a catalyst nd causes he viscous iquidto reactand becomeconvertednto a solid.The processof osmosis s usuallyattributed o one ofthree root causes:

Water ngress rom outside heyacht.Water ngress rom the inside:bilges, or instance.Reactivemourities n the resin.

Water ngress as been ound o be the causeof theproblem n about 85% of allcasesanalysed. uch casescan now be treaiedwith goodeffect. n his situationwater reactswith he impuritiesn the laminate r thepolyestertself, r the coatingageni on the glassreinforcemento form ree acidicsubstances.n hisprocess, nownas hydrolysis,he resinbecomesbrokendown into its componentpartsby the water. However, tis worth noting hat allpolymericmaterialsplastics)repermeablen waterand to watervapour o some degreebut it is the fact hat n the manufacturingrocessof theresincedain racesof un-reacted onstituentseads obreakdownand ultimatelvhe onset of what is referredto as osmosis'.

The effect of epoxy coatingson hull laminate moisturelevels:

The remaining 5o/o f cases,where eactivempurities rlamination eficienciesre he causeof the problem, rethe most difficulto treat. t is possiblehat he chemicalreaction t the resin-manufacturingtage s incomplete;that s, aboutO1% of the acid or alcohol emainsfree'in the resin. n such cases, he resinsuppliedo andused by the builderss incapable f beingcompletelyreacted.Effectively,he 'free'molecules f acid or alcoholareavailableo participaten secondaryundesirablendunintentionalhemical eactions ithin he laminate.Additionallyhe peroxide atalyst nd anyotheracceleratorssed do not form partof the solidmatrixand similady xistas impuritiesn the laminate. raceconstituents re known o reactwith elementsn watergenerating ompoundshat createpressure, hich sevidenced s blistersn the gelcoat.


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Stagesof OsmosisStage :Water enetration

Hull aminateGelcoatayerVoidsngelcoat& iaminateIns ide'dry '0utside water

Stage 2: Solutions form in voidsInitiallyn the gelcoat,where he moisture ontent shigher. nd thendeeper n the laminate s the conditionprogresses.Themoisture resent tads o break he resindownby hydrolysis.

Stage 3: Blister formationTheconcentrationells ormeddraw n moremoisturethatcausesblisters o form and swell.The ncreased ressure lso ends o acceleratethe breakdown f the laminate esin.

Stage 4: Laminate failureContinuingesinbreakdown nd ncreasing ressurein blisters eads o someblisters ursting.Deeper n the Iaminate,argeblisters ause aminatebreakdown nd eventualailure.

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Examination of Blister FluidsTheappearance f blisters elow he hullwaterlines thekey ndicationhat a laminate roblemexists.The blisterstake he formof a dome or, f pressure as caused hemto break,possiblya crater.Analysis f the blister luid s the usualmethodofdetermininghe type of problemwithin he hull.Thereare threecharacteristicshat can be quiteeasilv estedon-site:

e Thesmellof the blister luid:A strongvinegaryodour (oftenmistaken or styrene)ndicates hepresence f aceticacid,which s highly eactive.Pressure uildsup in the hullwhen he acidreactswith varioussubstances; he chiefproblemis calcium,which is present n both freshand saltwaterand forms calciumacetates.Thischemicalreactioncausessufficientpressure o form ablister.There s usuallysufficient reeaceticacidin the blister luid or the smell o be apparent.o The eelof the blister luidwhen rubbedbetween

fingerand humb.A greasy eel,simihr o thatof washing-upiquidor antifreeze,s due o thepresence f glycol n the resin.This reeglycolis soluble n water.o lts acidityor alkalinity s determinedby the uSeofpH paper.Testing he blister luid best takes place

at ihe moment he blister s brokenand he fluidreleased.The neutral eading as in the case ofOistltteCater is pH 7. Readings suallyoundfor GRP blistersare:pH 5 - pH 6: Acid readingThis is by far the most common result,andindicates hat freeacid has hydrolysedoff theemulsioncoating ormingacetic acid and otheraceticcompounds. Occasionallyeadingsas lowas pH 4 havebeen ound.pH 7 is neutral nd is sometimesound n vesselslocated n brackishor freshwatermooringspH 8 - pH 8.3:Seawater-filledlistersWaterhas penetrated he gelcoat.pH 9: Alkaline readingThis s very rare and indicates hat amineaccelerators ave been used eitherat thelaminatestageoii just possibly,at the resinmanufacturingtage.This s veryunusual nmore modernhu[s, so the implications re notdiscussed ere.

Tteatment and Ptotection OptionsDependingon the resuhsof the survey hree basicoptions can be considered:Option 1

Survey result Gelcoat n sound condition,no evidenceof osmosis.Recommendation:Protectionsystem.Even hough no osmosisappears o be presentthere s a continuing isk or all GRP/FRPboats.To minimise his, apply a thick epoxy coating(Gelshield 00) o the hull o create a separationlayerbetweengelcoatand water.This will delaythe onset of any osmosis hat is likely o occur.

Option2Survey esult:Evidence f osmosis ncludingblisteringn the gelcoat.RecommendationTreatmentystem.Full emoval f the gelcoat s likely o be requiredand replacinghe gelcoatwith he recommendedfilm hickness f Gelshield lusepoxybarriercoatingafter horough leaning nd drying.

Option3Surveyesult: xtensivelisteringndcratersin gelcoatand underlyingaminate.Recommendation:Removalof gelcoatandaffectedareasof laminate.Thorough leaning nd dryingprior o re-laminationwith Epiglass@poxy resinsystem andapplicaiion f Gelshield lusepoxybaniersystem.

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Option 1: Protection SystemDescription f systemA vesselwith no signsof osmosiswill benefit romprotection gainstosmosis. heearlierhis s done,the greaterhe benefits, nd some manufacturersreapplyingGelshield@00 to theirhullseitheras an optionor as standard quipment.Gelshield 00 is an epoxybarrier ystem hat servesthe dual unctionof the barrier ystemand antifoulingtie coat. Once he recommendedhickness as beenapplied t can be over-coated y any of the antifoulingsin the [email protected] is an epoxyprimerwith specific ormulationcharacteristicseveloped o offereasy application y avarietyof methodswhilst consistently elivering highlevelof protectionagainstosmosis.The solventbasedepoxy echnologydelivers xtremely ood adhasionothe surfaceand verygood toleranceo a wide rangeofapplication onditionsand temperatures. oaugment hebarrierproperties f the epoxy, ayeredmica has beenincorporatedwithin he formula hat createsan interlockingMicroplate'" ffectwithineach coat, which is highlyeffective n combatingwaterpenetration.It will also protectmetal ittings rom conosion,and so asingleproductcan be applied o hull,sterngear nd skinfittingso providemaximumprotectiono all undenvaterpartsof the vessel.Gelshield 00 can be applieddirectly o the gelcoatafterthe appropriate reparation. oller, rushor conventionalspraysare appropriate pplicationmethods,whilstairlessspray has he advantageof being able to deliver hegreatest oating hickness n eachapplication,educingthe time o complete he project.Once cured, he fullrangeof antifoulingsromInternationalan be applieddirect o Gelshield 00 asit functions s an antifoulingie coatas wellas a primer.lf the applications completedwithin he overcoatingtime specified, o sanding s required etween oatsof Gelshield 00 or subsequent ntifoulingayers.

Suggested Schemes orI]sets of Gelshield 200Gelshield200 applied by Brush/Roller or Conventional Spray:Gelshield200 (Grey)@.110 micronsWFT= 50 microns DFTInterfill830 as requiredGelshield 00 (Green)@ 110 micronsWFT= 50 micronsDFTGelshield 00 (Grey)@110 micronsWFT= 50 micronsDFTGelshield 00 (Green)@ I10 micronsWFT= 50 micronsDFTGelshield200 (Grey)as an antifoulingie coat @ 50 micronsDFT2 coats nternational ntifoulino

WaterlineGelshield00lnterfill30Gelshield00Gelshield00Gelshield00Gelshield00AntifoulingAntifouling

Gelshield 200 applied by Airless Spray:Gelshield 00 (Grey)@ 300 micronsWFT= 135 micronsDFTlnterfill 30 as reouiredGelshield 00 (Green)@3OOmicronsWFT= 135 micronsDFTGelshield200 (Grey)as an antifouling ie coat

@ 50 or 135 microns DFT(dependingn ypeof application)2 coais International ntifouling


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Option 2: Treatrnent SystemDescriptionf systemAnyyachtaffectedby osmosiswill need o haveall orpartof its gelcoat emoved.By definition, 'driedout:glassmatt rom which he gelcoathas been emovedis itselfan unsoundporoussurface, nd t follows hatapplication f a coatingover his ype of substrate arriesa certaindegreeof risk.GelshieldPlus has beendeveloped pecificallyominimisehese isks. t has he following ey attributes:Two ComponentChemicallyCuringEpoxy.It is a two-part, chemically uringepoxyproductwith a2:1 mixing atio.Epoxyhas beenchosenas beinga highlyimpermeable esin.Further, nlikepolyestershat haveverycriticalmixing atios, t is easy o mix n the boatyardenvironment. poxy esinsare not susceptible o thehydrolysishat is the rootcauseof typicalGRPosmosis.Solventless formulationThe benefitof a solventlessormulations that here s nochance,of solventmigratingnto he porousmatt surfaceand becomingentrapped n thosevoidspreviouslyoccupiedby the 'osmotically'introducedwater; hiswould atercreateproblems.Oneaccompanying nddesirableeature f the solventlessormulations, ofcourse, hat he operators not subjectedo anunoleasant olvent mell.High-build haracteristicsGenerally,he thicker he coating he morewater-impermeablet becomes.Gelshield lus,being100%solids,can be appliedup to 150 microns hick or thefirstcoat; an effective arrier an be builtup withonly4 coats.GelshieldPlus (BaseYAA222CuringAgent YAM21Blue,YAA220Green) s an alternative evelopmentin high buildsolvent reeepoxy or areaspreferringpigmented poxieswhilst etaininghe highlyprotectiveelementand extremelyow waterpermeationcharacteristicsf originalGelshield. he alternatingcolours id visibi l i ty henbuilding p the scheme.It has nherent oldup characteristicsigher han hoseassociated ith he originalGelshield,husgiving hepotentialo use one esscoat han n previousspecificationsosmosisreatment chemesof 4 coatsas against5 coats or the original roduct). dditionally,it hasa simplifiedmix ratioof 2:1 and he ability o cureat temperatures own to 10'C,some4 degreesowerthan he original ersion.Compatibility ith Interfill 30and Interfill 33 remains nchanqed.

Suggested Schemes forUsers of Gelshield PLUJ (YAA220 eries)Gelshield Plus used in the manner describedis the typical scheme:Gelshield Plus (Green)@ 150 micronsInterfill830 as requiredGelshieldPlus(Blue)@ 150micronsGelshieldPlus(Green)@ 150 micronsGelshieldPlus(Blue)@ 150 micronsGelshield200 (Grey)as an antifoulingie coat @ 50 or 135

microns DFT(dependingn yre of application.g. oller r ailess pray)2 coats lnternationalAntifouling

WaterlineGelshieldluslnterfill30Gelshieldlu sGelshieldlu sGelshieldlu sGelshield00AntifoulingAntifouling

Gelshield Plus used in conjunction with Epiglass:EpiglassEpoxy @-100 micronsInterfill 830 as requiredGelshieldPlus(Blue)@ 150 micronsGelshieldPlus Green)@ 150 micronsGelshieldPlus Blue)@ 150 micronsGelshield200 (Grey)as an antifoulingie coat @ 50 or 135

microns DFT(dependingn ypeof application.g. oller r airlesspray)2 coats nternational ntifouling

WaterlineEpiglassporylnterfill30GelshieldlusGelshieldlusGelshieldlusGelshield00AntifoulingAntifouling


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Option 3: Re-laminationand Treatment SystemDescription of systemEpiglass@Resins as repair systemsWhere aminates re physically amaged,EpiglassHT9000CYAA900eries) poxy esinsupplied sStandard ure,Slow cureor Fastcure havea role oplay.EpiglassHT9000 s a versatile poxy esinsystemwith a widevariety f uses he mostcommonof whichare sheathing nd lamination, lthough iven ts versatilityit alsogetsused orgluing,i l l ing nd airing. piglassEpoxy s extremely ater esistant.Repairing holes in laminatesWhen he blister amage s padicularlyevere,therema ybe a hole ight hroughhe hull aminate.Damaged aminates re often epaired y what scommonly alledhe pyramidsystem'.n thismethodthe damagedarea s cut back ntoa seriesof steps oenlargehe surface rea o which he repairwillbeattached. he appearanceherefores thatof a pyramid.Resinand woven oving s progressivelyuiltup in therepair reaonto a backingboardcoveredwith apolytheneheet, eldagainsthe nside f the hu,,.The board s removed nce he repair s completed.Thissystemprovides trong epairs uitableorovercoating ith he [email protected] methodof repair s widelyusedboth nthe yachtingndustry nd n commercial reas.

For full detailsplease efer o the GelshieldPlusApplicationManual, vailablero myachtpaint.com.Your ocal Internationalepresentative il l also behappy o assistwith echnical nquiries.lmportantNotes:All representationsnd statements oncerning he product(s)n this brochureare accurate o the bestof our knowledge.Statementsmade n his brochureare advisoryonly and are not intended o be specific ecommendalions r warranttes f anyproduct,combinationof productsor iitness or any particular urpose.To he extentpermittedby law,we do not acceptany labilityo ary personTorany ossor damage director indireci) hat may arise romany use of or reliance n anyof the methodsor information ontained n he brochurefor any purpose.UnlessotheMiseagreed n writing,all productssuppliedand technlcaladviceor recommendations ivenare subject o the Conditionsof Saleof our supplying ompany.Any watranties, f given,are contained n thosestancjardCondiuons f Saleand are he ontvonesmade with respect o any productswe seil o you or adviceor recommendations e give o you.For each of our products he relevantProductDataSheei, Nlaterial afetyDataSheetand package abelling omprisean integralnformation ystemabout he product n questlon.Copiesof our ProductDataSheetsand MateriaSafetyDataSheetsare availableon requestor from our website:M.yachtpaint.comInternationalnd allproductsmentionedn his brochureare rademarks f, or licensed o, Akzo Nobei.

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