Laminating Foam to Foam Question

Discussion in 'Fiberglass and Composite Boat Building' started by UNCIVILIZED, Jan 8, 2015.

  1. UNCIVILIZED
    Joined: Jun 2014
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    Location: Land O' the Great Lakes

    UNCIVILIZED DIY Junkyard MadScientist

    Gents,
    I ran across some inexpensive Divinycell recently, however it's a fair bit thinner than I'd prefer (by about half actually). The thing is, if I can figure out how to properly laminate 2 layers of it together, it'd be about perfect for the build I'm thinking on.

    Does anyone have any experience with pulling off such a "trick", or pointers on where to look, info wise?
    Also, it'd surely be nice to be able to laminate a couple of sheets together without adding a lot of weight to things. And I say as much, as somewhere ages ago, I recall a gent writing about using a layer of glass mat to do what I'm thinking. However, mat + resin = a lotta' weight, especially in relation to the foam. Plus, I'm thinking that it'd stiffen things up perhaps too much for the foam to be bendable around mold stations & such.
    Think he termed it a "club sandwich".

    Or, one of the build options I'm thinking on would entail laminating the foam onto one of the wooden skins of the boat, prior to vacuum bagging on the other skin (or laminating on some glass). So were I to go this route, what thoughts have ye as to how to laminate 2 layers of foam together, in situ? Prior to skin #2 going on.

    Thanks

    PS: If anyone's got some good links, or info about wood, foam, wood laminates, I'd surely appreciate them.
     
  2. gdavis
    Joined: Dec 2014
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    Location: belfast,maine

    gdavis Junior Member

    hello unciv,,core bond would be your first pick or you can use very thick epoxy. I have also seen grizzly glue used, it foams into the open cells of the foam. Are you bending the foam at all? If so you should probably glue them in one layer at a time. And it might be worth while to do a small test with one skin of ply on the foam before bending. It will still bend but not sure how much. Are you using kerf cut foam? I have never heard of or seen the club sandwich trick, its an extra step that isn't needed. What kind of boat are you building? Hope this helps you.........................................peace...g
     
  3. snowbirder

    snowbirder Previous Member

    I've done it with no voids.. Bogged between the sheets. A thin layer. And bagged it.

    Flawless.
     
  4. UNCIVILIZED
    Joined: Jun 2014
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    Location: Land O' the Great Lakes

    UNCIVILIZED DIY Junkyard MadScientist

    Thanks guys. As to designs, I haven't quite made up my mind as yet, thus I can't offer up any specifics on that, or the exact "recipe" for the build process. Though I really appreciate the thoughts.

    gdavis, I'd already figured that the foam might require a one layer @ a time application. No big worries about that, other than the extra time required.

    When you speak of using thickened epoxy to glue the layers together, I don't suppose that you have a ballpark figure on how much you used. As in, weight of the epoxy per square foot, not counting fillers (thickening material)?
    And, yes, I know, the best way to ascertain epoxy use data for gluing foam together thusly, is to build some test panels myself. However, any numbers which you guys can provide would help a lot. Especially in terms of calculating hull/structure weight, in addition to generating some rough numbers on costs.

    I gather that it'd make sense to first wet out the pieces of foam to be joined, with neat epoxy, & then spread on the layer of thickened epoxy. Perhaps with a notched spreader, albeit one with rounded, hemi-spherical notches, to prevent damaging the foam.
    Plus, after the cure was finished, odds are I'd need to do a bit of filling & fairing of the foam, prior to applying the other skin I mean.
    Ugh! Man do I hate longboarding. Although now, evidently, there are "short" longboards which are pneumatically powered. As to their efficacy, & user + project friendliness, I can't say.

    Thanks, & everyone enjoy their weekend!
     
  5. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    I would experiment with some small samples, using different methods. I do recall doing this many moons ago using a layer of mat and polyester resin between the sheets, but there are no doubt other, and maybe better ways.
     
  6. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    You could try "filling" the surface pores with a cheap, lightweight syntactic foam, to get a flat, slick surface you can then glue together with an economically small amount of epoxy, or some other suitable adhesive. Should not add much weight if done carefully.
     
  7. Tungsten
    Joined: Nov 2011
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    Tungsten Senior Member

    I know on Corecell foam it takes 30g 2/ft of neat to fill the peaks and valleys.Diviny I'm not sure.
     
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  8. snowbirder

    snowbirder Previous Member

    This is overkill

    You will use about 6-12 oz of liquid, mixed epoxy per full size sheet of Corecell.

    Just mix some microballoons in to get more volume from the liquid epoxy. The coat will be ultra thin. Painted on.

    You must bag this or you'll end up with core voids.

    Regarding epoxy.. you are building a boat. You will need more. Buy in volume. At least by the gallon from eboat/bateau. Their marinepoxy brand would work great here.

    Remember, you aren't bonding glass here. It's just core. So... even gorilla glue will work fine,except that it is much more expensive than epoxy.


     

  9. dinoa
    Joined: Oct 2007
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    Location: florida

    dinoa Senior Member

    The core to core bond and any filling goop need only be as strong as the foam. Most syntactic goop made of resin and filler will do. Stronger goo can be made by increasing the ratio of fiber fillers (cotton flox, milled glass, milled kevlar etc)

    Dino
     
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