Is this a good laminate/bond?

Discussion in 'Fiberglass and Composite Boat Building' started by filiperosa, Jul 30, 2012.

  1. filiperosa
    Joined: May 2006
    Posts: 49
    Likes: 3, Points: 8, Legacy Rep: 32
    Location: Setubal, Portugal

    filiperosa Junior Member

    Hello,
    I started to fiberglass a few small parts for my trimaran.
    I used foam core, after one first layer of 80 gsm one second layer of 540 gsm. On top of it one layer of peelply, bublewrap and was making vacuum for 5 hours at 15-20% (could no leave it during the night because neighboards.

    After a cure of two days, flip it over and the same procedure on the other side.

    I removed now part of the peelply and the fiber seams very uniform and all the fiber is wet. However as it is possible to see in the pictures it has some small gaps without resin. They are between the fiber parallel layers. They are very small and looks superficial.


    If I try to pull the laminate from the tip (Was testing a small part that I do not need) It is difficult but not imposible to pull. However the break happens in the foam itself, coming part of the foam with the fiber.

    It is this normal? Will I have a strong laminate? Any advices? Should I make gaps with a knife in the foam so the resin goes deeper?

    Sorry for all the questions but just want to make sure everything goes right.

    Regards,
    Filipe


    PS: In the photo what looks bublewrap is resin that come out and become solid around the bubles, the bubles are not there anymore.
     

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  2. rwatson
    Joined: Aug 2007
    Posts: 5,854
    Likes: 292, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    The small unwet bits are not an ideal thing to have, but depending on the part, you may get away with it.

    Re pulling the cloth away from the foam, that is not a structural test. You will get a few confused souls telling you that there is no penetration into foam, thereby making it a poor risk. The fact is, that unless the fibreglass is strong enough to hold itself together ( two sides, edges all holding itself intact) you cant expect the foam to do it for you.

    The point of foam is that the strength of the component is 'ALL' about its compressive strength, and relies very little on cloth to fibre adhesion. A proper design (layup schedule) allows for that.

    As long as the adhesion is good enough not to allow any moisture to accumulate between the foam and fibre, its fine. Especially if the foam is tearing, and not the fibre, it sounds quite OK. There is no reinforcement in foam so you cant expect it to resist the individual cells holding together.
     
  3. groper
    Joined: Jun 2011
    Posts: 2,467
    Likes: 123, Points: 73, Legacy Rep: 693
    Location: australia

    groper Senior Member

    Looks ok to me, i think your laminate is fine.

    Be careful about turning the vacuum off tho. The resin MUST be gelled or you will ruin your laminate by turning it off too early.
     
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