I stuffed up with the topcoat/gelcoat

Discussion in 'Materials' started by Rob McKeown, Sep 30, 2018.

  1. Rob McKeown
    Joined: Sep 2018
    Posts: 5
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    Location: Perth, western Australia

    Rob McKeown Junior Member

    Hi

    So I glassed some V seats into my 17ft half cabin.. I had two half used tins of gelcoat. Checked the ingredients.. both had styrene in them. First tin I used to do the edges etc and second tin for the main seats.

    Now the issue is 4 days later the main seats are still tacky when standing on them and when I give it a wipe with a little acetone it goes tacky. My understanding is the 2nd tin was actual gelcoat rather than topcoat. I had planned to paint with a marine paint over the whole inside so make it all uniform.

    Can I do this direct over the tacky gelcoat or do I need to strip it off and start again. Or could I give it a coat of topcoat .

    I hope this all makes sense. I find it hard to explain with writing rather than talking. The gelcoat is hard.. and not tacky to touch .. only when I stand on it etc
     
  2. Blueknarr
    Joined: Aug 2017
    Posts: 342
    Likes: 33, Points: 28
    Location: Colorado

    Blueknarr Senior Member

    Welcome to the forum

    Sounds like one tin was "waxed" gelcoat and the other "unwaxed" or one batch was in-catalyzed.

    Gelcoat is air inhibited. It doesn't cure hard if exposed to air while curing; even when properly catalyzed. Manufacturers use this to their advantage by "painting" the moulds first then gluing fiberglass to the gelled color coat. Each successive layer of polyester resin and fiberglass effectively sufficates the previous. Many factors determine the length of time the window of opportunity for successful bonding to of suffocation of polyester gelcoat. Usually measured in hours. You are nearly out of time, if not to late already.
    If you're sure of catylization:
    • Cover with plastic film or waxed paper. Ensure complete contact with film as any air bubbles will remain soft
    • PVA is also good gelcoat sufficant
    • Add layer of gelcoat and immediately suffocate
    • Use wax additive as surfacing agent
    • Suffocate existing gelcoat with regular paint
    • Remove sticky gelcoat and start fresh.
    • Not all of the above are compatible solutions
    Starting fresh is the only garenteed long term solution. The soft gelcoat SHOULD solidify if suffocated. ... It might not and problems may take years to manifest.

    Personally I would repaint. I give better than 99% odds that it will harden once separated from air.

    Good luck
     
  3. Rob McKeown
    Joined: Sep 2018
    Posts: 5
    Likes: 0, Points: 1
    Location: Perth, western Australia

    Rob McKeown Junior Member

    Thanks for the reply

    Yeah I've hit some of it with some pva to test it.

    Going to see the local fiberglass store tomorrow to get another tin of topcoat and see if I can get away with it with a 2nd coat.

    I'm sure i mixed the right amount of mekp.

    I guess it's all part if the learning process :)
     
  4. Rob McKeown
    Joined: Sep 2018
    Posts: 5
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    Location: Perth, western Australia

    Rob McKeown Junior Member

    Also first time building the glassing something like this and learnt a lot from it and tbh not that happy with the result. Did not curve with the hull as much as I'd like ( V shaped seats in a small cabin) I'm sure in a few years I'll rebuild them anyways so long term I'm not too fussed.
     
  5. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    PVA and other similar things only work when applied shortly after the gel is put in place and during the initial cure, not later.

    Most of the time if you paint over this semi cured layer it peels off later, the gel layer does not cure under the paint.

    Coating the I cured layer with more gel coat is normally the easiest method, the new gel coat will bond well if the surface is still softened by sanding or with a solvent.
     
  6. Rob McKeown
    Joined: Sep 2018
    Posts: 5
    Likes: 0, Points: 1
    Location: Perth, western Australia

    Rob McKeown Junior Member

    Pretty sure its cured. I tried to scratch a tacky spot with my nail and it didn't leave a mark.

    Fiberglass store is about to open so going to prep it for another coat but this time a topcoat. Or a 2 pack since the whole interior will need doing to get a good look throughout. Whoever originally painted the inside threw flecks throughout the topcoat. I'm going to repaint it a solid colour
     
  7. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    The speckle paint you describe is to disguise unevenness in the surface, which may show up if you use any sort of glossy coating. Normally flow-coat, which is waxed pigmented resin, is what is used in these situations, it cures tack-free, and is a dull matt finish.
     

  8. Rob McKeown
    Joined: Sep 2018
    Posts: 5
    Likes: 0, Points: 1
    Location: Perth, western Australia

    Rob McKeown Junior Member

    Ah now that makes sense. I was wondering why that was done.

    Yeah I dont have the skill as yet to get a nice flat finish. When I have some coin again I'm going to practice :) I would love to get a project at some point but I need to learn more first :)

    Least now it's not tacky :)
     
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