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Thread: Epoxy, does it have a shelf life?

  1. #1
    Spyderco Forum Registered User jackknifeh's Avatar
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    Epoxy, does it have a shelf life?

    I bought some epoxy at least two years ago. Possibly 3 years. For the last 6 months or so I've had knife handles come apart. These have all been back lock folders with one-piece handles. The handles have replaced the existing FRN handles. FRN Dragonfly2 is one of the knives that have had 2 or 3 handles come apart on one side or the other of the backspacer. I just finished fixing the handle but this time I used 3 3/32" pins through the scales and backspacer. I called USAKnivemakers and asked them if epoxy has a shelf life. They said yes, if not used within 2 or 3 years it may not hold as well as when used when it wasn't as old. I was surprised to hear that. But, I don't remember if I have glued handles together that have pressure applied "sideways" on the joining surface like the single piece FRN handles. The back lock spring appies constant pressure on the backspacer. I don't know if this makes holding the pieces together harder or now. Anyway, my question is has anyone else heard or experienced unused epoxy (resin and hardener) loosing it's adhesive capability over time? If not, I might assume my use of the glue may be improper. I've been using epoxy since I was around 10 years old and never had this issue before. I use coarser (220 grit or lower) sandpaper to roughen the areas making contact and make sure they are clean. Any help is appreciated.


    Jack

    My EDC for a while. Stretch with carbon fiber handle, Chaparral 2, Dragonfly 2 with kirinite MOP handle, Manbug with bolster/red bone handle. Super blue/420J1 blades on all three (except Chaparral).

  2. #2
    Spyderco Forum Registered User Pinetreebbs's Avatar
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    It will age, most products have an expiration date. Stored open or under less than ideal storage conditions, especially high heat, it will deteriorate faster.

    I have used epoxy stored for several years, just waste the stuff near the opening, mix some up and see if it will set. If it will not set, try a bit more hardener, if that does not work, toss it in the trash.
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    Spyderco Forum Registered User The Deacon's Avatar
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    There's another possibility. The resin in the epoxy and the resin in whatever handle material you are using just don't play well together. I know that can be the case if you try to epoxy something made of casting resin. The joint seems ok, until you put a bit too much pressure on it. Scuffing the surfaces helps a bit, but not much. Just not sure if the resins used in things like G-10 and CF are also incompatible with epoxy.
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    Epoxies and Other Glues are Temperature sensative

    Many of those glues are temperature sensative and extremely hot temperatures will probably ruin them. I have some really great epoxy glue called PC7 that can repair about anything. I even used 2 cans of it to make a handle for a fixed blade knife that I found in the timber at a local lake. I believe it was an older Case fixed blade so with 3 applications I made a superb handle for it. And that PC7 epoxy that I used the other day was at least 3 years and maybe 4 years old and it still worked like a charm. The PC7 is more like the consistency of a heavy polymer rather than 2 thin liquid substances like most epoxy glues are formulated. PC7 and it's marine grade brother product PC11 are both superb products and it's unbelievable the things you can repair with them.

    There are a lot of good glue products on the market but I haven't yet found anything better than PC7 or PC11. You might go to your local hardware store and they can probably tell you what the average shelf life of your product is. If you have stored it in a temperature controlled environment you are probably all right.
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    Spyderco Forum Registered User jackknifeh's Avatar
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    Quote Originally Posted by JD Spydo View Post
    Many of those glues are temperature sensative and extremely hot temperatures will probably ruin them. I have some really great epoxy glue called PC7 that can repair about anything. I even used 2 cans of it to make a handle for a fixed blade knife that I found in the timber at a local lake. I believe it was an older Case fixed blade so with 3 applications I made a superb handle for it. And that PC7 epoxy that I used the other day was at least 3 years and maybe 4 years old and it still worked like a charm. The PC7 is more like the consistency of a heavy polymer rather than 2 thin liquid substances like most epoxy glues are formulated. PC7 and it's marine grade brother product PC11 are both superb products and it's unbelievable the things you can repair with them.

    There are a lot of good glue products on the market but I haven't yet found anything better than PC7 or PC11. You might go to your local hardware store and they can probably tell you what the average shelf life of your product is. If you have stored it in a temperature controlled environment you are probably all right.
    I found this on ebay. I'm going to try this unless you say it's not the best option. I found other items also. Some in cans, some in plastic syringes, etc. This stuff looks great for applications in addition to knife handles. Even applications under water and other places having nothing to do with knives. Anyway, do you recommend this or some other product or some other purchasing site? Thanks for any help.

    Jack

    My EDC for a while. Stretch with carbon fiber handle, Chaparral 2, Dragonfly 2 with kirinite MOP handle, Manbug with bolster/red bone handle. Super blue/420J1 blades on all three (except Chaparral).

  6. #6
    Spyderco Forum Registered User
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    Quote Originally Posted by jackknifeh View Post
    I found this on ebay. I'm going to try this unless you say it's not the best option. I found other items also. Some in cans, some in plastic syringes, etc. This stuff looks great for applications in addition to knife handles. Even applications under water and other places having nothing to do with knives. Anyway, do you recommend this or some other product or some other purchasing site? Thanks for any help.

    Jack
    Jack I think you can even buy PC7 and PC11 both directly from the company that manufactures it. It is a family owned business and I've chatted with them a couple of times and they were very accomodating and full of good product information. I've found that PC7 is actually far stronger than most of the materials you are gluing together most of the time. When I made that knife handle out PC7 I was just experimenting and to my pleasant surprise it's one of the best knife handles I've ever used. That stuff when it's dry is chemical resistant, heat resistant and definitely waterproof beyond belief. I've personally never found any epoxy or any other glue for that matter that is better than PC7 or it's marine grade brother PC11.

    PC7 is dark gray in color when it dries and PC11 is white in color when it dries. The people that make PC7 told me you can even painit if you use a good quality primer on it. Good Luck and let us know how it works out for you.

    Jack I'm not sure of what you are attempting to repair or whatever. But there is another product very similar to PC7>> you know it by it's household name "JB WELD". However I've found PC7 & PC11 to work better on big jobs. But both products work well and are very high quality. JD
    Last edited by JD Spydo; 06-13-2014 at 03:29 PM.
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  7. #7
    Spyderco Forum Registered User jackknifeh's Avatar
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    Quote Originally Posted by JD Spydo View Post
    Jack I think you can even buy PC7 and PC11 both directly from the company that manufactures it. It is a family owned business and I've chatted with them a couple of times and they were very accomodating and full of good product information. I've found that PC7 is actually far stronger than most of the materials you are gluing together most of the time. When I made that knife handle out PC7 I was just experimenting and to my pleasant surprise it's one of the best knife handles I've ever used. That stuff when it's dry is chemical resistant, heat resistant and definitely waterproof beyond belief. I've personally never found any epoxy or any other glue for that matter that is better than PC7 or it's marine grade brother PC11.

    PC7 is dark gray in color when it dries and PC11 is white in color when it dries. The people that make PC7 told me you can even painit if you use a good quality primer on it. Good Luck and let us know how it works out for you.

    Jack I'm not sure of what you are attempting to repair or whatever. But there is another product very similar to PC7>> you know it by it's household name "JB WELD". However I've found PC7 & PC11 to work better on big jobs. But both products work well and are very high quality. JD

    The problems I've had with epoxy not holding recently has been when making handles to replace the one-piece FRN handles. I make two scales and a backspacer then glue them together. After the knife is assembled the lockspring puts lots of force on the backspacer trying to make it slide between the scales. I cut small grooves on the inside of the scales and on the sides of the backspacer but that didn't work. Now that I'm thinking more I don't remember having this problem in the past. Maybe it's only happened when I use kirinite and G-10 (backspacer). The epoxy I used is the 2-ton stuff from USAKnifeworks. They think the glue got old after 2-3 years. I don't know. I'm going to try the pc7 though. I may try forming a handle with it. Have to think about that. I wish it were clear. Then you could put stuff inside it or a liner under it. I have been wanting to work more with C-TEK also. It has different levels of translucency and a colored liner glued to the bottom of c-tek is something a lot of people do. But if the glue is grey that may be a problem.

    Jack

    My EDC for a while. Stretch with carbon fiber handle, Chaparral 2, Dragonfly 2 with kirinite MOP handle, Manbug with bolster/red bone handle. Super blue/420J1 blades on all three (except Chaparral).

  8. #8
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    Surface Preparation is #1 priority

    Quote Originally Posted by jackknifeh View Post
    The problems I've had with epoxy not holding recently has been when making handles to replace the one-piece FRN handles. I make two scales and a backspacer then glue them together. After the knife is assembled the lockspring puts lots of force on the backspacer trying to make it slide between the scales. I cut small grooves on the inside of the scales and on the sides of the backspacer but that didn't work. Now that I'm thinking more I don't remember having this problem in the past. Maybe it's only happened when I use kirinite and G-10 (backspacer). The epoxy I used is the 2-ton stuff from USAKnifeworks. They think the glue got old after 2-3 years. I don't know. I'm going to try the pc7 though. I may try forming a handle with it. Have to think about that. I wish it were clear. Then you could put stuff inside it or a liner under it. I have been wanting to work more with C-TEK also. It has different levels of translucency and a colored liner glued to the bottom of c-tek is something a lot of people do. But if the glue is grey that may be a problem.

    Jack
    Well Jack there is one very important factor to using PC7 or PC11 or any other high quality epoxy glue >> and that is surface preparation. You really need to rough up the area that is going to be glued with some type of abrasive or sandpaper and also I highly recommend some type of prep solvent like Laquer thinner or any other type of solvent that will really clean up the area well.

    Because you can get PC7 to stick to just about anything if you have the surface clean and somewhat scoured and abraded to give it something to adhere to. Glue of any type is just like a premium paint>> surface preparation is probably about 70% of the job. Because without doing it failure is almost a certainty.

    The Protective Coatings Company who is the maker of PC7 has some great tips on their website as well as some other websites out there.
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  9. #9
    Spyderco Forum Registered User demoncase's Avatar
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    Epoxy resin has a very short shelf life if kept outside of ideal conditions (room temperature and about 50% humidity)- even then, I'd say 12 months is probably the limit.
    The higher strength the epoxy, the greater the concentration of reagents in the mix and- sadly- the reduction in shelflife.

    If it's got hot at any point (about 30oC) in storage then it may not even set at all due to degradation of the hardener (epichlorohydrin).
    Higher than 80% humidity for long periods will have a similar effect if the tub/bottle/tube isn't sealed well.
    If it does actually cure, you can expect and Ultimate Tensile Strength of significantly less than the original- typically 50%, but even down to 10%.....Seen this happen at work where a glued joint simply peels apart with light finger pressure.

    If it seems like it's taking an age to cure, and stays 'wetter' than you're used to during mixing, it's cooked and fit only for the bin
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  10. #10
    Spyderco Forum Registered User chuck_roxas45's Avatar
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    Quote Originally Posted by JD Spydo View Post
    Well Jack there is one very important factor to using PC7 or PC11 or any other high quality epoxy glue >> and that is surface preparation. You really need to rough up the area that is going to be glued with some type of abrasive or sandpaper and also I highly recommend some type of prep solvent like Laquer thinner or any other type of solvent that will really clean up the area well.

    Because you can get PC7 to stick to just about anything if you have the surface clean and somewhat scoured and abraded to give it something to adhere to. Glue of any type is just like a premium paint>> surface preparation is probably about 70% of the job. Because without doing it failure is almost a certainty.

    The Protective Coatings Company who is the maker of PC7 has some great tips on their website as well as some other websites out there.
    I agree about surface preparation. I just read this thread now and I was going to post about roughening the surface and having it clean of contaminants but bro JD had already beaten me to it.
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