How to fix slow-curing fiberglass resin: MEKP diluted with?

Discussion in 'Materials' started by kayakingsteve, Aug 27, 2021.

  1. kayakingsteve
    Joined: Aug 2021
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    Location: Florida, United States

    kayakingsteve Junior Member

    Have some fiberglass repairs that aren't curing well (living in 90%+ humidity everyday probably doesn't help)

    Was reading somewhere about diluting MEKP with ??? (forgot what) and spraying or brushing it over resin that's not curing fast enough to speed up the process.

    Am I mis-remembering? Could diluted MEKP on the surface fix the curing? What would one dilute it with?

    Thanks for any help!
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    Ondarvr is the man to ask here, but some additional heat may help. Is it just sticky, or is it not gelled ?
     
  3. Blueknarr
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    Blueknarr Senior Member

    Is this the repair from a few weeks ago?

    If so --- nothing is going to kick it.
    Scrape it off and start over.
     
  4. kayakingsteve
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    kayakingsteve Junior Member

     
  5. kayakingsteve
    Joined: Aug 2021
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    kayakingsteve Junior Member

    This is glass I put on today, but the cure time is supposed to be a few hours, and it's out to about 8 now.

    It's cured somewhat, just tacky in spots.... almost seems like any resin over-spread that's not directly on the glass fabric doesn't want to cure yet.
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    Unwaxed resin ? If the thicker part is setting up, the thinner should go off OK
     
  7. kayakingsteve
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    kayakingsteve Junior Member

    Far as I know. Just the cheap, generic glass resin you pick up at any hardware store, with the MEKP hardener tube in the lid.

    Maybe I'll set it out in the sun tomorrow.

    With very high humidity should I use more hardener and work in smaller sections?
     
  8. Mr Efficiency
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    Mr Efficiency Senior Member

    You can usually say 1% in hot weather, 2% in cold weather for catalyst, with room "in-between". Thin lay-up takes longer to cure, the humidity makes unwaxed resin remain tacky, don't adjust catalyst based on humidity
     
  9. kayakingsteve
    Joined: Aug 2021
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    kayakingsteve Junior Member

    That IS interesting. My brain is trying to use glue or paint logic with this, so I'm imagining thinner layup dries faster, but is there some kind of reaction in the resin/glass that means thicker actually heats up or something, hence curing faster?
     
  10. Blueknarr
    Joined: Aug 2017
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    Blueknarr Senior Member

    Are you using "finishing " or "laminating " resin. Finishing has a bit of wax added to make it cure with a hard surface. Laminating doesn't have any wax and cures sticky so that the next layer adheres better. Laminating can be used as a final coat if an inhibitor is used. Wax can be added to the mix. Or PVA (not from dyi paint store) can be applied over it. Or plastic film can be layer on top. Or...

    Resins are thermo-genic. Thick spots heat up more and cure faster.
     
  11. kayakingsteve
    Joined: Aug 2021
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    kayakingsteve Junior Member

    This... this is the part where I put my palm on my face, because this is going to sound stupid. I just grabbed Bondo fiberglass resin. Figured it would work... I can't tell if it has a wax or anything in it...

    This is probably an example of poor planning/ignorance... what SHOULD I get next time for small fiberglass repairs that are meant to be one-step repair, sanded and painted over?
     
  12. Blueknarr
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    Blueknarr Senior Member

    Fiberglass resin is nothing like paint. Paint dries (solvents evaporate) then hardens. Polyester resin hardens first before any solvent can evaporate. After it cures, styrene can take decades to evaporate out.
     
  13. BlueBell
    Joined: May 2017
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    BlueBell "Whatever..."

    I would suggest three things:
    1.) use more MEKP (but watch your max percentage - look it up),
    2.) use a more square container to maximize your bulk and
    3.) let it stand ten minutes (after mixing for five minutes) before applying.
    Bonus idea: warm up the resin before you use it.
     
  14. kayakingsteve
    Joined: Aug 2021
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    kayakingsteve Junior Member

    Do you think the tacky stuff is unhardened resin, or could be it be some residue of something else that won't go away soon? If there are still tacky spots in 24-48 hours, what should I do?
     

  15. Blueknarr
    Joined: Aug 2017
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    Blueknarr Senior Member

    Did a quick web search.

    The pictures of bond avaliable at Lowes could not be read clearly.

    If they claim it to be sandable, then it should be pre-waxed.

    Is wax listed in the ingredients?
     
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