Using 3M Super 77

Discussion in 'Fiberglass and Composite Boat Building' started by tomherrick, Feb 28, 2012.

  1. tomherrick
    Joined: Sep 2006
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    Location: Versailles, Kentucky

    tomherrick Junior Member

    Doing a search here on 3M Super 77 I see that a number of folks have used it to hold fiberglass in place before wetting out with resin. I haven't seen much regarding details of how and, possibly more importantly, how not to use it. Pieces of 1708 stick well to some off-boat tries and I like the idea of using it. My concern is that too much may keep my epoxy from bonding to the substrate.

    Anyone here have some guidelines I might use to ensure a good bond in my laminations when I use the Super 77?
     
  2. mydauphin
    Joined: Apr 2007
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    Location: Florida

    mydauphin Senior Member

    Never used it, but used similar products, let it dry throughly otherwise it might have a funky reaction from the outgases.
     
  3. CatBuilder

    CatBuilder Previous Member

    Not to be annoying, but I have to say I am very satisfied with using Raptor composite staples for this purpose. I was too paranoid to put anything on my foam, even though many people use spray adhesives in this manner.
     
  4. tomherrick
    Joined: Sep 2006
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    tomherrick Junior Member

    Those staples sound like a good approach into foam, and not annoying at all. I don't have foam however, and also want to be able to use the Super 77 for successive laminations over previously cured epoxy.
     
  5. rasorinc
    Joined: Nov 2007
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    rasorinc Senior Member

    3 M has a Marine Department at their headquaters. Call them with your questions, I have and they were real helpful.
     
  6. bntii
    Joined: Jun 2006
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    bntii Senior Member

    Just roll some neat epoxy on before you drape the cloth.
    Everything will stick & the wet out will go faster.

    BTW- skip using the "08" with the mat and use straight 17 oz biax. To my mind it is extra bulking for no gain when using epoxy resins
     
  7. tomherrick
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    tomherrick Junior Member

    Thanks, rasorinc. They were helpful as they could be, but didn't have specific information on compatibility between Super 77 and epoxy. He did find in their database that there is a history of using Classic Formula Super 77 with epoxy and fiberglass, but didn't have any further info. He referred me to the 3M industrial tech support who had less information. Still working on it.
     
  8. tomherrick
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    tomherrick Junior Member

    bntii, I might have skipped the 08 but it's sewn onto three rolls of 17oz biaxial that I already own.
     
  9. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Lightly spray (I mean lightly, just an easy dusting) the surface to have the 'glass applied. let the vehicle flash off then apply the fabric. If used as described, you'll have no adhesion issues. I've used this technique dozens of time for overhead work and it's more effective then using your bald spot as a squeegee or fabric prop.

    Ditto the comments about mat in an epoxy laminate, you're just wasting fabric and resin, not to mention time.
     
  10. bntii
    Joined: Jun 2006
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    bntii Senior Member

    Ya- I had a hull side peel off one time when I spun around to get the roller- custom epoxy/glass sombrero ..
     
  11. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Thomas, I've previously attempted a hair restoration technique very similar to what you've described
     
  12. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    You can buy epoxy compatible adhesive to hold the glass in place, its about the same cost. The 3M product can cause problems in both epoxy and polyester laminates, if used correctly the risk isn't that high, but why take the risk at all.
     
  13. tomherrick
    Joined: Sep 2006
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    tomherrick Junior Member

    ondarvr, can you tell me who makes the epoxy-compatible adhesives? Tech support at U.S. Composites recommended against using 3M Super 77; probably over liability concerns, but still...
     
  14. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I know of no compounds in 3M 77 that will causes issues, assuming you let the vehicle flash off first. If the 3M 77 is applied heavily, the compounds will remain in suspension in the cured epoxy matrix, becoming little more then frozen particulates.
     

  15. ondarvr
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    ondarvr Senior Member

    The clumps of glue that are against the surface and on the glass can restrict and block flow, plus where ever the glue is there is no bond. This is even worse when gel coat is involved (either resin) because there is zero bond where the droplets of glue land on it. As the gel coat is exposed to water, sun and heat these spots can become visible surface defects, or blisters.

    Worst case you get dry spots and delamination with either resin. Some shops use it, some opt for the stuff designed for that purpose.
     
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