Epoxy second layers

Discussion in 'Fiberglass and Composite Boat Building' started by Manie B, Nov 26, 2008.

  1. Manie B
    Joined: Sep 2006
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    Location: Cape Town South Africa

    Manie B Senior Member

    Gents - something is not so good

    PLEASE HELP

    The first layer of epoxy onto new marine plywood goes on well, i always give the plywood a light sanding, vacuum clean and wipe with a clean cloth and methelated spirits to ensure that there is no oil or grease from hands and fingers, epoxy soakes in well

    then after about 2 to 3 days curing i am left with a "blush" that is sticky and oily, almost greasy. I wash this with a pot scrourer "brillo pad" water and dishwashing soap - it cleans well - you can feel the difference, THEN SAND DOWN WELL. Then i wipe down well with a clean cloth and fresh water to remove all traces of soap. Wipe dry and then wipe down with a little meths to ensure no oily residue left behind - dry very well - it is very hot here 30 to 32 celsius so i know the wood is clean and dry before i apply the second coat

    NOW THE **** HITS THE FAN

    The second layer forms an "orange peel" that is just not spreading - i have brushed until my arms want to fall off - but still after a while the "orange peel" seperation re-appears

    WHATS WRONG :?:
     

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  2. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Use denatured alcohol to remove the blush and scrub. You're probably leaving slight amounts of it in the low spots. Then wash off with clean water with a little vinegar in it.

    Apply your next neat coat with a foam roller (one intended for epoxy or solvents), then lightly tip off to remove bubbles. A gas torch works well at popping remaining bubbles too.

    Brushing is a very inefficient way of applying epoxy. A roller, spreader or squeegee are far more effective tools. These tools lay down a uniform coating, which can be cleaned up with a foam brush.

    The picture looks like a viscosity issue, not over coated blush. What is the work temperature? Resin temperature? You're better off working in smaller batches with hot resin, then larger batches of cooler resin, that doesn't "flow out". Consider bringing your resin up to 80 degrees, where it should flow out nice. You'll have less working time, but the results will make it worth it.
     
  3. Manie B
    Joined: Sep 2006
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    Location: Cape Town South Africa

    Manie B Senior Member

  4. Wynand N
    Joined: Oct 2004
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    Location: South Africa

    Wynand N Retired Steelboatbuilder

    Manie, I would take the easy way out and just spray the stuff on, what can be easier than that and the finish would be smooth....or am I missing something here:?:

    Maybe it is Rettie chasing you for not visiting me yet:D
     
  5. Jimbo1490
    Joined: Jun 2005
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    Location: Orlando, FL

    Jimbo1490 Senior Member

    The gummy coating you have encountered is something called 'amine blush', which sometimes happens with certain polyamine curing agents. The best way to remove this is with denatured alcohol, as PAR suggests. Simple soap and a scuff pad will work, too, though you should still follow up with an alcohol wipe.

    I suspect that your 'orange peel' and poor flow-out of the subsequent coats is caused by something that's left behind by the Brillo pads. Those things are for cleaning pots. They have all sorts of unknown substances in them that might not be compatible with what you are doing. For instance, these pads have anti-corrosive agents like waxes and silicone resins that coat the surface of the pot you are scrubbing to prevent (in the short term) rust from forming on cast iron. An alcohol or MEK wipe might work to remove this, a commercial wax and grease remover like 'Prep-Sol' could work, too. But I think it's just easier not to put the offending substance on the surface in the first place.

    Jimbo
     
  6. Fanie
    Joined: Oct 2007
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    Location: Colonial "Sick Africa"

    Fanie Fanie

    Will you still have the problem if you apply the first layer of epoxy and glass instead of painting with resin only ? Ply should still absorb to seal ?
     
  7. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Good catch Jim, I didn't think about the waxes they put in those Brillo Pads.

    If this is the case, they surely are water soluble and should wash off.

    To me the first image (the green one) isn't focused enough to really tell, but the second one looks like a flow out issue (viscosity). I don't know, maybe they are fish eyes and I'm just not seeing it.

    Most often when the surface is contaminated with something like wax, you will actually see the epoxy pull away from these areas, as you apply it. If you reapply over the area or try to brush it out, they reappear in the exact same spot. This is when you know there's something on the surface.

    I guess we need more information about temperature, how did the goo feel as it was being brushed on, etc. Come on Manie, screw up another batch and tell us how it went . . . I'm betting on it being a prep issue (90% of the time it is).
     
  8. Manie B
    Joined: Sep 2006
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    Location: Cape Town South Africa

    Manie B Senior Member

    Dont worry i will be back at it tonight

    keep you posted

    spraying is not on :D

    working with epoxy "in my house" is already problematic :D

    thanks for the support guys

    Fanie even with glass the blush still comes up and has to be removed for painting

    Wynand i will get to you after the 12th when i shut down for the holidays - thanks anyway :D

    i am looking forward to my leave
    4 weeks of boat building and boating
    heaven to me
    hell is working for a living :D :D :D
     

  9. Roly
    Joined: Jul 2005
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    Location: NZ

    Roly Senior Member

    I use peel ply. Saves time & aggro.
    A thinned out flow coat (10%) then peel ply.
    Remove the peel ply (and the blush goes with it).
    Hit it with another flow coat.
    Quick and easy.
    (West systems)
     
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