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Epoxy setting/drying time?

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by Danbo, Jan 21, 2008.

  1. Danbo

    Danbo Platinum Member Platinum Member

    Nov 28, 1999
    How the frig long does it take for Loctite's Extra Time 60 min epoxy to cure? I mixed some up last night and actually glued up some canvas micarta slabs on a blade(a monumentous feat for me). Clamped it up, went to bed. Got up about 7 hours later, had breakfast, and then went to the shop to shape the micarta. I figured something was wrong, when one of the pins started to move(pins also were epoxied). I even put the damn knife in the kitchen oven for an hour at about 150, since Mr. Krein and Burnley recommended that. When shaping the micarta flush with the tang, I noticed it was still sticky, as a little was oozing out from under the slabs. Right now, almost 20 hours later, that one pin still moves a bit. I realize the label says it takes 24 hours for full set up, but I've never had epoxy take this long before. Certainly never happened with the Devcon. Is it me or is it the Loctite brand epoxy? Or, am I simply not waiting long enough?
  2. AcridSaint


    Jun 23, 2006
    Unless the pin is mosaic, I would pien it, epoxy generally won't hold it in well. Not sure what to tell you about the glue drying, sorry.
  3. steelshaper


    Jun 14, 2007
    Well after 7 hours it should not be oozing. I have used loctite and hve never had this problem. To venture a guess either it was not mixed well or you got a fluke bad batch. Still with the 60 min you should have waited longer. Even the instant set is gummy after 3 hours. A question what temp was the epoxy at when aplied? Was it setting up in a very cold or very hot room? It says on the package -10 to 120 is the temp rating, and it will take longer to cure in the cold.
  4. raythebigfoot


    Sep 12, 2007
    I have used loctite before and had problems with their epoxy though I never used the 60 minute one. Switched to devcon and never had the problem again so I can only guess that it was the epoxy I was using.
  5. Danbo

    Danbo Platinum Member Platinum Member

    Nov 28, 1999
    As it's about 10 degrees outside, I did all the prep work and clamping downstairs, where it's nice and warm in my computer room. I noticed that the pin would still move about an hour ago, and in fact, pushed out. :confused: None of the other pins would move, and neither would the lined thonghole. So, I cleaned up the one pin, remixed some more epoxy and reset the pin. It's a waiting game now, and I'll not touch the knife until this time tomorrow.
  6. blgoode


    Oct 3, 2003
    hit it with a heat gun or hair dryer real well....then check it again in the morning. Dont get it too hot just enough to set off what still may be soft but savagable.
  7. rebeltf


    Jan 29, 2005
    I'm wondering if you perhaps did not mix it up well enough before using it ?

    60 minute epoxy should have set overnight.

    I've always used 5 min epoxy and never had a problem with it.
  8. butcher_block

    butcher_block KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Dec 6, 2004
    locktite can kiss my back side.

    i used it once cause i was in a pinch and need a knife finished that night (it never set up)

    cost me 2 days and a drop in price cause of late
    devcon 2 ton was out of stock at the store i was at
  9. bikermikearchery


    Jan 18, 2007
    I've had the same thing happen with Locktite epoxy. Just wouldn't set up. Locktite is the only one that has ever done that to me. I have had other brands have a long delay of 10 or so hours but they did set.
  10. Leu Custom

    Leu Custom

    Jun 2, 2007
    I have used the same exact epoxy you've used from Loctite probably. [comes in a syringe with dual tubes?]

    Let me just say that I thought of using it to saturate some japanese cord wrap and thought it would be dry overnight. WRONG! I think it was about 10 days later, it still felt TACKY to the touch. Have never used that stuff since! I think you're better off using DEVCON or something like that. :D
  11. steelshaper


    Jun 14, 2007
    I have never had a problem with loctite but I use the 5 min. stuff. I guess though its better safe than sorry and I will make sure to never buy loctite again.
  12. For best results always add a little extra hardener to make sure it sets up correctly!
  13. DeadeyeLefty


    Jun 2, 2007
    I just deleted a long(er?) post on epoxies (aviation & boatbuilder background) but, suffice to say that the epoxies that are sold in hardware stores aren't the best formulations. If it's in a twinned syringe, it's not as good as it could be. A marine supplier might be a better choice for resins, hardeners, and fillers.

    To be clear, the time quoted on packaging is not (NOT NOT NOT !!!) cure time, despite what the manufacturer says. It is gel time ('pot life') and it's the point where the epoxy can no longer be deformed without structural damage. For the majority of users of prepackaged products, this is sufficient to do the job while the curing continues. This can take days, or WEEKS for cold-cure epoxies. If the temperature is too low during the cure phase, it may never set up.

    A slight temperature change can have exponential impact on cure time. Temperature of the materials being joined (substrate) is so important that the epoxy's temperature is almost irrelevant. Any surface contaminants that are oil or solvent based will also affect the bond (see: 'may never set up', above::grumpy:)

    Epoxies are great stuff, but to discuss the merits of prepack stuff is like comparing different fast food burgers: they all suck, and there's WAY better product available.
    Check out the Gougeon Bros. website. They make West System stuff and have great info and test data that (IME) seems to be true in general, regardless of whose resin you buy.
    No affiliation here, BTW

    I've never worked with phenolic resins (billiard balls, Micarta) so I can't offer anything there.

    EDIT: Sorry striper, I'm afraid someone's led you astray - this is probably the most common misconception about epoxies. In an epoxy formulation, the 'plastics' are split between resin and hardener. Changing this relationship changes the final composition of the finished product.
    The grain of truth (there always is...) is that this is true with polyester/vinylester resins where all of the 'plastics' are in the resin and a catalyst is added simply to initiate the chemical reaction that causes the resin to harden. Adding more catalyst to poly resin makes the reaction (exotherm) happen sooner and faster. Not so with epoxies, you'll actually decrease ultimate strength if you alter the ratio.
  14. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    DeadeyeLefty beat me to it: There is an exact ratio with epoxy. Weighing it is the best way to mix it.Change the ratio (which is what most likely happened) and it may not cure right.

    With hardware store epoxies, some may have been on the rack much longer than the shelf life, and won't set up properly.

    Why would you use anything but the best grade epoxy to glue up the handle of your several hundred dollar knife?
    Use ONLY an epoxy made for this purpose (K&G sells a 24 hour cure that is excellent) or an epoxy made for similar work (Acraglass or marine resins).

    Final note - Don't clamp tightly. You will squeeze out all the glue and the scales may pop off later.Clamp just snug enough to hold the scales in place ( about the same as finger tight). Since I use Corby rivets, I don't have to clamp at all. I just tighten them to squeeze out the excess, clean them up,inspect the joints, and let the handle cure (another reason for 24 hour set epoxy).
  15. richard j

    richard j

    Apr 1, 2007
    forget the locktite crap, get some devcon 5 minute epoxy. get everything set so you can put it together after applying the epoxy and get it clamped. i used to use slow set epoxy till i had a similar problem.

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