laminating resin

Discussion in 'Fiberglass and Composite Boat Building' started by Cjmac, Mar 12, 2018.

  1. Cjmac
    Joined: Mar 2018
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    Cjmac Junior Member

    So im kinda new to laminating resin iv always used epoxy or finishing resin. But i want to build a small box for a few small gauges that will mount on top of my console. Haven't decided yet how im going to mold it . . But with laminating resin i understand i can cure it with gelcoat that has wax. But how long should i let the laminating resin (cure) or sit before i attempt to brush on the gelcoat ? And how thich should the gelcoat be ? Correct me if im wrong but my plan is.... lay up the glass , let is kick off , paint with gelcoat to let resin cure , sand flush. then using a fairing putty to fill any print through of the weave or other imperfections. Sand to a finish im happy with and add a good final coat of gelcoat .. done ...thanks
     
  2. jorgepease
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    jorgepease Senior Member

    It sounds like a small project, I think you would be better served if you built a small mold, get that fair, apply gelcoat, your glass, resin and pop it out ready to go. You might even be able to find a plastic container or other ... that will serve as your mold.
     
  3. fallguy
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    fallguy Senior Member

    sounds like a female mould would be easier

    build the basic shape of the box with corecell or plywood with say hotglue, then build a female shape that fits over the box

    the female can get some nice contours and fillets made and then you fair it all out and wax and pva; it'll be a bit easier and come out looking more professional than building over the male box the way you describe..
     
  4. Blueknarr
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    Blueknarr Senior Member

    I prefer to suffocate Gelcoat with PVA or waxed paper over adding wax to final coat of gel.
     
  5. rwatson
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    rwatson Senior Member

    For something so small, just apply glass over a wooden box, and paint it with a good quality gloss house paint or a "Flowcoat" type of product.

    Mucking around with Gelcoat is just a pain in the ar..m.
     
  6. Cjmac
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    Cjmac Junior Member

    A plastic box is a good idea
     
  7. Cjmac
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    Cjmac Junior Member

    Thought about thin plywood . I jave used epoxy on plywood lids on old jon boat and painted them .. could build a box and glass over it ... probably take a few coats resin to soak in before i lay glass ?
     
  8. Cjmac
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    Cjmac Junior Member

    Fairing compound before gelcoat ? Wouldn't you have gummy sand papper trying to sand down the fairing compound with the uncured or ( tacky ) surrounding resin .. sorry still learning on laminating resin
     
  9. rwatson
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    rwatson Senior Member

    No, this "soaking into plywood" is just a fairy tale.
    Put an initial coat of epoxy over the ply, maybe use a warmish heat gun to make it flow into any imperfections, then just lay over the first 16 oz glass, squeeging as you go .
    Once it "goes off", and is just a bit tacky, apply the final coat.
     
  10. SamSam
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    SamSam Senior Member

    If you are talking about using polyester resin, there are three things you can do. Use the finishing resin and skip the first gelcoat. Add wax to the laminating resin and skip the first gelcoat. Seal the surface of the laminating resin with PVA or plastic film, and skip the first gelcoat. Polyester resin is air inhibited, so the air has to be sealed off somehow for the resin to cure hard in a short time.
     
    Last edited: Mar 17, 2018
  11. Blueknarr
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    Blueknarr Senior Member


    The fairing compound must cover FG completely. 1st to ensure hard cure. 2nd it is difficult to sand fair two substrates simultaneously, as one will sand down faster than the other
    If the lamination is done well, then gelcoat fairing is possible. Depends on fairness of lamination and expectations of final product.
     
  12. Cjmac
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    Cjmac Junior Member

    How long should PVA stay on for a full cure . ? I can get some locally
     
  13. Cjmac
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    Cjmac Junior Member

    Oh ok , starting to understand this ...
     
  14. Cjmac
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    Cjmac Junior Member

    I may just spray with pva . Peel it off and go from there.
     

  15. Blueknarr
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    Blueknarr Senior Member

    I encourage you to try Gelcoat immediately after laminating followed by sprayed ova from your resin supplier. (The pva used to prime sheetrock don't work so well with polyester.

    Gelcoat is my go to fairing compound when repairing production hulls.
     
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