aluminum with adhesive...

Discussion in 'Materials' started by tws, Aug 13, 2015.

  1. Deering
    Joined: Feb 2005
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    Deering Senior Member

    I'd use a thickened marine-grade epoxy for this fix. Something like West System with some added microfibers to help with gap-filling, strength and flexibility.

    Hand sand with something like 150 grit (nonmetallic!) abrasive to give good tooth. Then apply an aluminum etching compound to removed oxidation shortly prior to the epoxy (make sure it's dry first). The etching stuff can be had at most quality paint shops.

    As mentioned above, if you tape a piece of poly plastic, like a freezer bag, tightly over the wet epoxy, it won't stick to the epoxy and it'll leave a smooth surface when you remove it. The epoxy will cure just fine under the plastic - it doesn't depend on air to off-gas volatiles like paint or some other adhesives do.

    Epoxy is not UV stable, so you'll need to apply a little paint over it. Surface prep with abrasive and follow paint instructions. You could go with the same color as the skiff, or make a dripping blood red gash. Tell people you had a run-in with Jaws rather than admitting that you ran into something. Why have a boat if you're not going to lie about your (mis)adventures?
     
  2. tws
    Joined: Aug 2015
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    Location: southern oregon

    tws Junior Member

    never thought about treating aluminum like glass. thanks for the creative input... indeed we fisherfolks sometimes embellish the truth...
     
  3. CDK
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    CDK retired engineer

  4. Mr Efficiency
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    Mr Efficiency Senior Member

    Being well above the waterline means it is not a critical repair, were it on the bottom it would require a proper fix. A bloke a few doors down from me imported a second- hand car from the US. It has a bullet hole in the boot (trunk) lid. Another job for a sticker !
     
  5. whitepointer23

    whitepointer23 Previous Member

    Cool, saves buying fake bullet hole stickers.:D
     
  6. waikikin
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    waikikin Senior Member

    What's the chances that Elvis owned it..................

    If I was to consider epoxying a Gouge-on a boat I'd definitely use west system.....

    Jeff.
     
  7. tws
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    Location: southern oregon

    tws Junior Member

    thanks CDK,
     
  8. tws
    Joined: Aug 2015
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    Location: southern oregon

    tws Junior Member

    Jeff,

    the west system has been around for years i first heard about it in the boat yards of southeast alaska... laminating wood etc. i would avail myself of this system/method of repair but i don't want to buy a many component process for just a minor scratch... does the west system offer a small kit for aluminum repair?

    thanks,

    tws
     
  9. waikikin
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    waikikin Senior Member

    Hi tws,

    Just a bad pun mate(apologies), the west system is marketed by the Gougeon brothers......

    Some "knead it" or belzona($$$) or any similar would be fine, just tooled off flush, I 'd just put the sticker over & not bother with the filler..

    Jeff
     
  10. tws
    Joined: Aug 2015
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    tws Junior Member

    thanks jeff,

    i'm looking at that aluminum putty that was posted... quite spendy! $50 a pop! so i'll probably do something less expensive. and i've already ordered the decals to put over the gouge...
     
  11. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    West System is the industry leader, though you do pay for this status. Any marine grade epoxy will do and you can use aluminum oxide as a filler, along with some silica (viscosity control) to stiffen it up, enough to be non-sagging. The color will be slightly different, but it would be all you's need for the repair.
     
  12. Steve W
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    Steve W Senior Member

    You could use a toughened epoxy such as G flex as it has much better tolerance to differing expansion/contraction rates but remember that epoxy does not like UV exposure so unless you are going to paint it I would add some pigment or if you want it to look like aluminum add some aluminum powder although G flex is yellowish so it may not color it enough. As far as adhesion to aluminum goes people tent to forget that all the tensile strength specs published by the epoxy manufacturers are derived from coupons of aluminum bonded together, properly prepped of course. The West systems folks ceased selling the two step chemicals for cleaning and etching the aluminum a few years ago when tests showed that they got better tensile strength from bonding aluminum with G flex without the chemical prep than the did with their 105 epoxy with chemical prep so they now recommend G flex for aluminum.

    Steve.
     
  13. dinoa
    Joined: Oct 2007
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    dinoa Senior Member

    Normally bonding aluminum with epoxy is not recommended especially in a moist envoirenment. My guess is West is probably adding a bonding agent such as an organosilane to their G-flex to get around the aluminum prep.
     

  14. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    G-Flex isn't a toughened epoxy, in fact the opposite is true. It's marketed as a "toughened" goo, but the reality is, it's actually weaker in most regards. Where it gets it's unique properties is its dramatic tensile elongation, which is typically 10 times that of standard formulations of marine resins. It's hardness is also notable being about as soft as skateboard or roller skate wheels, while regular formulations are more like the plastic used in a hard hat. Generally its compressive yield, tensile and flexural strength are 1/3rd to 1/2 of regular formulations.

    West System Six-10 is a toughened epoxy (thickened premix), using a few fillers to accomplish this. It too has an elevated elongation modulus, about twice that of regular formulations, but the other physical attributes are similar.

    Lastly this is an old thread.
     
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