laminating resin

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

  1. Cjmac
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    Cjmac Junior Member

    Well the only gelcoat i have already has the wax mixed in it
     
  2. Cjmac
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    Cjmac Junior Member

    If i use like a 4 or 6 oz cloth the print through shouldnt be to awful. With epoxy i always used enough to fill the weave . How thich can gelcoat be ?
     
  3. Blueknarr
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    Blueknarr Senior Member


    Unfortunate about the pre-waxed gelcoat. When I have used waxed gelcoat, the pores where the wax rose to the surface were visible. Use it if its what you have.

    Fill the weave with polyester just like you did with epoxy.

    Gelcoat can be applied very thickly. 2mm sanded back to 1mm.
     
  4. Cjmac
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    Cjmac Junior Member

    I remember reading something a while back that if gelcoat is applied to thin it may not cure properly stay kinda soft or sticky . Is there any truth to that ? I seen i have some 1.5 oz chop , 6 oz cloth left should be plenty for what im going to do . Wife just caught me looking at the Tupperware, she said dont even think about i know your up to something :D
     
  5. Cjmac
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    Cjmac Junior Member

    I also need to be careful of it becoming resin rich , as with epoxy it doesn't matter . I can see myself now standing there saying , is that to much ? Ill add a little more .
     
  6. Blueknarr
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    Blueknarr Senior Member

    Some. If waxed gelcoat is to thin, an insufficient amount of wax will raise to the surface.
    By the way pva reacts badly with waxed gelcoat.
     
  7. Blueknarr
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    Blueknarr Senior Member

    If you take the same precautions with poly as you do with epoxy, there should not be problems with resin richness. All hand layups tend to be slightly over resigned. Still ok with poly, if no pools. Adding Cabosil will help prevent over resination. If part is not structural, less problems if over resin.
     
  8. rwatson
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    rwatson Senior Member

    I've lost track. You keep mentioning epoxy, and others are talking Polyester resin with Gelcoating.

    Perhaps you could clarify.
     
  9. Cjmac
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    Cjmac Junior Member

    Im in the learning process of using polyester resin and gelcoat...

    i only have experience with epoxy .
     
  10. rwatson
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    rwatson Senior Member

    Learning Gelcoat and Polyester wont hurt, but the Plywood /Epoxy will work just as well for the small project if you just want to get it done.
     
  11. Cjmac
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    Cjmac Junior Member

    It would probably be faster .. but rather use the poly that it just sit there . He gave me the quart of resin and gelcoat just cause i get so much stuff from him
     
  12. SamSam
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    SamSam Senior Member

  13. ondarvr
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    ondarvr Senior Member

    This is getting far more complicated than needed.

    First, working with polyester isn't that much different than working with epoxy, so don't stress over that part.

    Polyester resin will cure to almost tack free on its own after a couple days, no need to "cure the surface" with waxed gel coat.

    It will be easier to wet out the glass correctly with polyester because the viscosity is lower and it's less likely to sag or drain out of the glass.

    Finding a plastic tub or waste basket the right shape to use as a mold will be the easiest method, making a mold out of plywood wouldn't be that hard either.

    For this purpose waxed gel coat will work, but you need to apply the laminate while the gel goat is still a bit tacky, otherwise the wax can compromise the bond.

    If there are small pits or defects in the gel coat due to the wax, then you did something wrong.

    You don't need any PVA.

    Anytime you coat wood with resin you need to pre-coat the wood, otherwise you can run into problems.

    You can make a plywood shape and coat it with glass, or you can use the same shape as a mold, the wood shape will take about the same amount of work to build. Making a glass coated plywood part requires a great deal of work to make it smooth and glossy, using the plywood shape as a mold requires less sanding and fairing for a good finish.
     
  14. redreuben
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    redreuben redreuben

    Make a female mould from glossy melamine coated ply or mdf, you ran radius the internal corners with plasticine and a drill bit for the radius. Wax and/or pva for release.
    First coat, gelcoat (no wax) so there are no windows, (2 coats is safe) the gelcoat is ready to glass when you wipe it with a knuckle and no colour comes off.
    Glass it with laminating resin and use peel ply if you want a tack free no sand surface.
    If you have wax free resin it will dry sticky but will cure underneath, not an issue, you can finish it with waxed gelcoat (flocoat) anytime.
    PVA glue/primer is polyvinyl acetate.
    PVA release agent in polyvinyl alcohol.
    They are not the same thing and are not substitutable.
     

  15. redreuben
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    redreuben redreuben

    P.S You can buy wax solution to add to resin/gelcoat separately it is simply paraffin wax (as used to seal jam) dissolved in styrene monomer. You can actually do that yourself too by buying the wax and styrene separately too !
     
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