Pin holes in finish.

Discussion in 'Fiberglass and Composite Boat Building' started by Carbonman, Aug 3, 2009.

  1. Carbonman
    Joined: Aug 2009
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    Location: Chicago

    Carbonman Junior Member

    So first off Im new to the forums and I know I should use the search and I have. But I wanted answers specifically to mysetup. It woudl make me feel at ease

    So heres a quick runup of how I layup my parts.

    I have a clearn taped and prepped mold. I lay over 3 layers of carbon fiber fabric followed by peel ply, green mesh flow media, peel ply again, and a boarder of breather. spiral wrap with vacuum at one side and a small tube that lets the resin in from the opposite side.

    I start off by turning the vacuum on for at least an hr before letting in the resin and when I do let the resin in I do it slowley to saturate everything well.

    I do check for leakes and double bag the product to secure myself from any air leakes.

    I let the resin in and all goes well. I see tiny air bubles and try to push Them to the edge but nothing goes.

    I let the part cure before I pull it out and when I do BAM a few to a dozen pin holes ...

    I tried epoxy resin thinned with laquer, epoxy resin straight but its kinda thick, and I tried polyester resin.

    The surface has to be clear so I cant use any kind of colored gel coates. But if I try a clear gel coat I am certain I will still have air pockets with in the visible top coat instead of pin holes. At least pin holes I can fill them in with clear. Although that does take extra time. I think why not just deal with filling each one in afterwards and just clear coat over it then sand it smooth. Well Id like to have the parts come out nice the first time to speed things up.

    If anybody can help me Id much appreciate it

    Look forward to spending hrs and hrs on these forums!
     
  2. TeddyDiver
    Joined: Dec 2007
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    Location: Finland/Norway

    TeddyDiver Gollywobbler

    Sounds like of gasing.. but not sure. You can make little a test.. pre heat some resin (some bubles should show up) and let it cool down and before adding hardener...
     
  3. Carbonman
    Joined: Aug 2009
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    Location: Chicago

    Carbonman Junior Member

    Good idea. That should let it degas its loose gasses Im guessing?
     
  4. Stumble
    Joined: Oct 2008
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    Location: New Orleans

    Stumble Senior Member

    There aer a couple of ways to degass resin, first is heating it which causes the trapped bubbles to expand forcing them up and out. The second is to place the resin under a vacuum for a couple of hours. This does the same thing as heating and can be combined. If this solves your problem then it was just small air bubbles trapped in the resin due to its viscosity.

    The problem with both of these methods however is that they can leave disolved gasses in the resin. These disolved gasses become supersaturated under a vacuum but may not release from solution. To accelerate this process you need nucleation sights to pull the gasses out of the solution.

    There was a thread a month or so ago where I went into detail on exacally this problem, but the poster was actually having the epoxy foam up instead of just a few bubbles.
     
  5. Carbonman
    Joined: Aug 2009
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    Location: Chicago

    Carbonman Junior Member

    It didnt work :( It still bubbled...

    Whats the best way to just fill them? I was thinking a foam brush with clear resin, wetsand, then clear coat with urathane clear until we get enough f unds to get more advanced equipment.
     

  6. jim lee
    Joined: Feb 2007
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    Location: Anacortes, WA

    jim lee Senior Member

    I'm betting you don't need advanced equipment. Did you try clear gelcoating the mold first?

    We've seen that -anywhere- you have a resin blob in your part, a place that isn't mostly glass, it will form a bubble. (During infusion) Where your drystack is packed in tight, you don't see bubbles. Are they just too small? Donno'.

    -jim lee
     
    Last edited: Aug 3, 2009
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