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Epoxy glue problem

Discussion in 'Luthier's Corner' started by tantetruus, Oct 4, 2010.


  1. tantetruus

    tantetruus

    Jul 3, 2010
    Hi,

    today i tried routing a neck and part of it came loose
    in a big way:scowl:
    I made a laminate using epoxy.
    The part that came loose broke on the epoxy seam.
    So, practically no wood broken on both sides, just the epoxy itself.

    Anyone had this problem too?
     
  2. Musiclogic

    Musiclogic Commercial User

    Aug 6, 2005
    Southwest Michigan
    Owner/Builder: HJC Customs USA, The Cool Lute, C G O
    Nope, don't use epoxy on lams for just this reason. Epoxt doesn't always penetrate the wood fibers enough to be a stable assembly adhesive, and shrinks quickly, thus is always changing. Titebond, PVA, or Hide are usually your best choices.
     
  3. Skelf

    Skelf

    Apr 15, 2005
    Moffat D&G Scotland
    Builder AC Guitars.
    A lot depends on the epoxy and how old it is how well it was mixed. Also the brand and the time it sets in. If it is some generic brand with a 5 min set time I am not surprised. If you use something like West Systems then I think you would be all right.
     
  4. ZolkoW

    ZolkoW

    May 8, 2006
    Hungary, EU
    whad woods did you use?
    when I first epoxysed my padouk bass body from two pieces, they actually fall apart after two days.. padouk -for example- is really oily wood, I had to use PVAC - and it worked perfect.
     
  5. tantetruus

    tantetruus

    Jul 3, 2010
    thanks for the replies all;
    As for composition; i use epoxy fresh from the producer, and mix it on an electronic scale
    so, i dont think the problem lies there.
    What i do see is that it doesnt seem to penetrate that much so thats an (expensive) lesson on epoxy:(

    The laminate is wenge and maple.
    The wenge is kinda oily too, but i noticed that a bit wenge came off in the break and no maple came along so in that respect it seemed to have penetrated it a bit.
    I was quite surprised to see how easy it is to scrape the remains of the epoxy off the wood, not to much holding power on the wood it seems, more to the epoxy itself.
     
  6. What did you use to prep the surfaces that were being adhered together? Also, did you score the surfaces? I like roughing them up a little.
     
  7. tantetruus

    tantetruus

    Jul 3, 2010
    i used aceton.
    I only sanded it a bit, but roughing might have been a better idea:)
     
  8. I like doing both... but then I think people have nicknamed me "Overkill" behind my back.
     
  9. pilotjones

    pilotjones

    Nov 8, 2001
    US-NY-NYC
    My first question would be, how did you prepare the surfaces for jointing? When you checked them after doing that, how planar were they? Second question, what glue did you use, and how was it prepared, and applied? Third question, how did you clamp them, and for how long? What were the ambient conditions?



    I am finding padauk to be very dry, not at all oily, and easy to glue. Beyond that, epoxies are often recommended for oily woods.
     
  10. JoeDeF

    JoeDeF

    Apr 15, 2009
    The very best way I know to get epoxy to adhere is to wet-sand the pieces with the freshly mixed epoxy. Put on gloves, spread (unfilled) epoxy on the wood, and then sand the epoxy into the wood surfaces. Then, cover the wood with another spread of epoxy, and clamp the pieces together. Epoxy, unlike PVA glues, relies upon the mechanical bond between the wood and the cured epoxy, and sanding the epoxy into the wood creates great mechanical interlock.

    Also unlike PVA glues, epoxy is stronger in larger quantities than in small, so don't clamp it excessively tightly, or you might squeeze out so much of the epoxy that there is not enough left to
    create a strong joint.

    As other posters have noted, the specific brand and formulation of epoxy makes a huge difference. I've never had even the slightest hint of failure with WEST System when properly mixed and applied. Nor with System Three. What epoxy did you use?

    While some companies and users recommend acetone to remove oils from the wood prior to epoxying, others say that unevaporated acetone left in the wood can interfere with the epoxy adhesion. I don't know for sure one way or the other, but I wanted to mention it because it could have something to do with the epoxy failure in your case.

    Also, what was the temperature in the room where you applied and cured the epoxy? Too low a temperature can also lead to epoxy failing to cure properly.
     
  11. tantetruus

    tantetruus

    Jul 3, 2010
    The temperature and mixture where conform advise.
    The mixture was done exactly to the gram (electronic scale).
    The brand is a company over here in the netherlands.
    I will contact them too.

    My guess so far is that the epoxy didnt "get in the wood" enough; it appaers to be "on" the wood instead of "in" the wood.
     
  12. ZolkoW

    ZolkoW

    May 8, 2006
    Hungary, EU
    epoxy bonds to the surface - if it's too smooth, it won't bond strong. roughing is a good idea. that's why it won't work on oily woods - (I don't consider wenge to be too oily, but my piece of padouk WAS). PVAC (maybe titebond is something similar, I don't know that) works in a different way, it "vulcanizes" the woods together.
     
  13. mikeyswood

    mikeyswood Inactive

    Jul 22, 2007
    Cincinnati OH
    Luthier of Michael Wayne Instruments
    No. Just no.
     
  14. Acetone is very volatile. Unless someone used fingernail polish remover in lieu of 'straight' acetone I can't imagine that they had time to even mix a batch of epoxy and apply it before the acetone evaporated.
     
  15. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    Feb 28, 2021

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