Pin hole foam boards versus normal boards for hand lamination?

Discussion in 'Fiberglass and Composite Boat Building' started by Jaco, Sep 20, 2021.

  1. Jaco
    Joined: Sep 2021
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    Location: South Africa

    Jaco New Member

    Good day,

    We have a project where we want to create a simple structure using foam core and then laminate with hand on both sides. However, the foam core boards I can get all have pin holes (1.5mm holes all over the board). Would the pin holes create any problems, or can I use these boards as I would with normal boards?

    Do I need any extra steps with the pin holes? I am going to use epoxy resin.

    Do I need to coat the foam boards with epoxy first, or can I laminate with epoxy on the clean boards?

    Thank you very much,
    Jaco
     
  2. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    You could make up some lightweight filler and fill the holes, like using putty in nail holes before you paint, otherwise resin will drain through them to some extent. Q-cell and resin would do it.
     
    fallguy likes this.
  3. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    The pin holes or perforations are designed for vacuum bagging.

    Follow Mr. E and make a mixture of thickened resin. Make sure it is fairly thick or it may sag into the holes; I'd probably add a bit of fumed silica. If this is for a hull bottom; I'd do it a day ahead, to avoid air pocketing if you have any sag. Otherwise, for the inside of a hull or other parts; same day is good. Fill, then glass.
     
  4. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    The pin holed foam will require slightly more resin than non-perferated.
    They will increase the resistance to delaminate.
    No changes in procedures for near vertical surfaces.
    No changes I procedures for the second skin.
    There is a possibility of resin dripping out of the underside of near horizontal surfaces. Wipe away any drips before they harden. Or pre-filled with thickened resin.
     
  5. fallguy
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    fallguy Senior Member

    sounds messy
     
  6. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    The problem with resin that might drain through holes and form globs on the underside, is it is hard to sand them off without damaging the foam.
     

  7. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    100%
     
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