Swim platform mold build gone wrong, help needed

[firebird1158]

So I spent a lot of time getting what I thought was gonna be a great mold ready for an extended swim platform for my Doral 300se but after wet sanding down to 1200 and waxing the mold with carnuba 10 times I started the gelcoat which very quickly started to bubble up in areas... It seemed to start setting up too quickly as well even though I used the recommended 1.5% hardener per volume... it was 21 degrees celcuis( 70 far) in the garage... so not really sure what went wrong. I'll throw some pics of the project and see what you guys think. thanks in advance

 

[firebird1158]

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[firebird1158]

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[firebird1158]

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[Scott Danforth]

looks like too much styrene

 

[firebird1158]

looks like too much styrene

I didn't use any styrene, just brushed it on... stopped as it was starting to gel and saw the wrinkles

 

[Scott Danforth]

If the gel is old it will kick fast as well

 

[Woodonglass]

How old is the gelcoat? How long after waxing the mold did you apply the gelcoat? It appears to me that a chemical reaction is occurring between the substrate and the GC. What is the mold made from?

 

[firebird1158]

the mold is made from melamine but i primed and painted it and sanded to a nice finish. i just peeled a part of the gelcoat that was setting up and there was some of the blue paint on it. i peeled a part that was wrinkled and seems like the blue paint was wet. thinking the 10 coats of wax didnt keep it out. i waxed 8 coats yesterday and 2 earlier today , then gelcoated this evening. gel is new and fresh as its was color matched at boat builder supplier this week. they sell alot of resin and gelcoat. wondering now if i should have waited for my pva to show up tomorrow. although everyone says wax is good for my project. anyway i sprayed the remainder with all my wife’s hairspray! lol guess its as good as pva! that will harden it up hopefully and will probably have to sand the whole dam thing again. maybe i should gel the remainder and sand out bad spots to have a new layer to keep away from that blue paint... which was rustoleum painters touch by the way. bad choice im thinking.

thanks for the help

 

[Woodonglass]

Yup for molds I don't recommend painting the melamine surface is ideal and works by itself. You might want to consider starting over. Be careful NOT to apply to thick of a coat of GC due to HEAT. I'd also recommend using multiple CSM HAIRY pieces (pieces torn and pulled apart to make very loose and plable pieces dabbed into place. For Fabric I'd use 2-3 layers of 8ox biaxial fabric. Easier to conform to the mold and very strong Cardboard tube cut in half lengthwise make great supports once glassed into the lamination

 

[firebird1158]

Ya, i was just trying to get a smoother finish. , also i had to join 2 pieces of melamine with body fill as its 9.6 ft wide which made a smooth seem and hence the idea to smooth it all out. you think if i gel over it all and sand smooth and wax and pva that when i pull the new one the first coat of gel will come out as well seeing how it is waxed underneath? my plan was to do surface veil, chop strand and 1/2inch nidacore, going to add some nidacore stringers as well for added support. ive seen the cardboard tubes before and may include if i run low on nidacore. , thanks again for the advice.

 

[Woodonglass]

Uhmm I'd think you'd want more of a textured surface on a swimplatform. The finished gelcoat surface should be about 10mils. You then begin laminating the CSM and Glass Fabric. Gelcoat won't stick to a waxed surface. If you're worried you can also spray the mold with PVA. A piece of clear packing tape over a crack will leave an imperfection that is easily sanded. Again and Hull Like slick finish on a swim platform is not ideal.

 

[firebird1158]

I have eva foam teak for the top surface, hence smooth finish, if eva doesn’t work out in long run id add an antislip. never thought of the packing tape seam! thanks! Was going to do 2 , 5 mil coats of gelcoat as with large area wanted to do 2 batches for time.

 

[Woodonglass]

Good plan on 2 coats. Make sure to put the second coat on just as soon as the HEAT from the first one has almost completely dissipated. If you're covering with teak. The melamine by itself will yield a very smooth slick surface.

 

[firebird1158]

thanks, what would you use for covering sides and round over fillets? i used 1/4 masonite and sheetrock 20 for fillet, sands easy. would wax and pva be good enough? any tricks to possibly removing the gelcoat that i just applied to half the mold? thanks

 

[Woodonglass]

let it cure for a day then flip the mould over and smack it down on the worktable or drive way. If it doesn't pop out then start over. The wax and the pva should seal the plaster as well. Again any slight imperfections are easily sanded and polished once the casting is removed. I also Put down 3 -4 coats of wax 1 hour between coats. Wax EVERYTHING very well. Then spray 2-3 light coats over everything and make absolutely certain that every bit of the mould is covered. This is a very important step and should be carefully completed.

 

[firebird1158]

Well striped the mold and thought id just flip it over and redo sides but had a bunch of nail holes so started with a fresh sheet of melamine. this time i got a different Idea on the sides and reused the old ones except i used black formica contact cemented on that was only 2.50 a sheet. super glassy smooth, should give nice finish to sides. no the debate about what i should use for the fillet round overs. seemed like the gel stuck a little to the plaster i used last time and i bumped the side a couple times and it separated leaving a small crack. thinking lightweight body fill this time. Can you use silicone? any specific type better?

 

[firebird1158]

Heres the updated mold, any specific tape for the crack?

 

[sphelps]

Just a guess .. Plastic wood filler maybe ?

 

[Woodonglass]

Clear plastic Packing tape.
The body filler will work fine but...The KEY is to ensure it's completely covered with the release agent, I'd spray 2-3 coats of PVA and it should be fine.