fiberglass staying tacky due to low catalyst

Discussion in 'Fiberglass and Composite Boat Building' started by mrdebian, Dec 19, 2022.

  1. mrdebian
    Joined: Apr 2021
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    Likes: 11, Points: 8
    Location: Greece

    mrdebian Junior Member

    As per title, one of my friends who came to help me on a project made a mistake and instead of 1.5% catalyst he added 1.5 ml which equals to 0.75%......
    I added a coat on top of the cloth with 3% catalyst and in one of them (there are 2 kayak rim molds) it hardened or at least it looks like after 8 hours at 19-20oC.
    The 2nd one even after so many hours (9+) at same temperature is still very tacky.
    Is there any tip on saving this?
     
  2. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    I never let anyone run my mixes. 300 gallons of epoxy and 3 mix errors by me. One took me 8 hours to remove(forgot to stir). The other two, for some reason, I used 2 ounces of hardener and one ounce of resin or reversal of the quantities. Those were fillers and scraped away what was exposed.

    If you can get it out of the mold; just scrap it.

    @ondarvr or @rxcomposite would be the only two forum members I'd accept a repair idea from
     
  3. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell . . . _ _ _ . . . _ _ _

    I am no expert but my experience has been it'll kick eventually.
    A heat gun would help.
     
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  4. kapnD
    Joined: Jan 2003
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    Location: hawaii, usa

    kapnD Senior Member

    You can add a hot batch over while chemical reaction is strong, but it will be ineffective later, say the next day.
    Pre prepping batches expected to be used in the day is my best method of avoiding mix ratio problems, but things like failing to mix a batch just happen to humans, especially those working under pressure and stoned out on fumes!
     
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  5. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    On a thin laminate you can frequently get away with putting more resin over it, don't get carried away and over catalyze it though, that's just as bad as under catalyzed.

    Heat helps, but don't over do it either.
     
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  6. rxcomposite
    Joined: Jan 2005
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    Location: Philippines

    rxcomposite Senior Member

    There is nothing you can do except remove the layer and sand if it is a thick layer or just throw the part away. MEKP is an initiator and is consumed in the process of crosslinking. If there is not enough, then the process is not complete and will remain uncured/rubbery.

    However, this is a mold and is not subjected to safety factor. If you have a improperly cured layer, no life threatening consequense will occur. You can heat it up as others have suggested to shorten the curing process but it will still be a weak layer. Don't expect a non tacky surface though. Don't overdo it. Laminate remains tacky if exposed to air because it grabs the moisture in the air and inhibits it from curing,

    Advice to the builder- If this is the first time you are doing it, always perform a batch test in accordance with the manufacturers data sheet. If you change brand or supplier, always make another test.
     
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  7. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    I don't believe this is a mould, so this is why I suggested to scrap, but it might be only a part like a coaming.

    For a whole boat, I wouldn't feel too good about using a botched hull..
     
  8. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    It didn't sound like a critical part, and having it cured will help in de-molding. If it isn't good when pulled from the mold it can be tossed.
     
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  9. mrdebian
    Joined: Apr 2021
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    Location: Greece

    mrdebian Junior Member

    Thanks for the replies. It is in a mold; 3 layers of 300 mat and a few patches along with gel coat. I do need to be cured in order to release it to avoid any problems with the mold.
    I will check later today and see how it is.
     
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  10. mrdebian
    Joined: Apr 2021
    Posts: 98
    Likes: 11, Points: 8
    Location: Greece

    mrdebian Junior Member

    Just an update that the item released from the mold fine. It took 2 days at 20-22oC.
     

  11. KD8NPB
    Joined: Mar 2018
    Posts: 162
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    Location: South Carolina

    KD8NPB Senior Member

    Forced air heater blown across the piece. Tarp it to create a low temp oven. Bake at ~100F for 30-45 min.
     
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