Epoxy shelf life

I am preparing to resume work on a Wood Duck after a hiatus of about five years because of health issues. I have a considerable amount left of the same MAS epoxy that came with the kit and am wondering if it will still be effective. The jugs state a 12-month shelf life. I have mixed up a small batch of a few tablespoons and am waiting to see if it hardens. If not, there's my answer, I suppose. But even if it does harden, I have no way of knowing whether it has the same protective properties as fresh epoxy. It has been stored on a shelf in a cool basement, if that makes any difference. I never capped the jugs, just left the pump tops on them, if that makes a difference. Question is, who out there knows whether I should use it or bite the bullet, toss it out and buy a new supply? Second question, if it does harden but is not suitable for use on a kayak, would it be worth retaining for hobby applications? Third question, if I do toss it, is there an environmentally sound method of disposal? Thanks in advance for any info.

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RE: Epoxy shelf life

I'd mix up some and "glue" some sticks together. Then after it sets up, think 24 hrs. try and break them apart. If the wood breaks before the epoxy joint I say it was still good. 


RE: Epoxy shelf life

i routinely have used MAS epoxy as old as you describe (and older).

you can call the MAS technical support..i am not sure what they will tell you. but from my perspective, if it hardens, i am not aware that it is any less good for kayak construction than 'fresh' epoxy.  the boats that i have built with old epoxy have held up for years with no apparent ill effects.

similar to yours, mine have always been stored indoors and capped (and having the pumps in them is effectively capping them).

you may find the pumps not performing well....but if they work...then that's fine too.   

the current boat i am working on, has its epoxy dating back from about 2014 and it is performing just great.


RE: Epoxy shelf life

Test some of that stuff, see if it cures within the time frame your working temperature indicates it should. If it does, you can trust it.

Hardener's less risk-prone from storage than resin. Biggest issue with resin - other than contamination, which is easily overcome by keeping container effectively closed off from atmosphere, is crystallization.

That the stock packaging is opaque makes this hard to evaluate. But a strong light source (LED flashlight or similar) held against the jug's outside to show what's inside (being in a dimly lit room helps) will let you judge whether the stuff inside looks milky & lumpy or clear & liquid-like. Or pour a quantity into a clear container so you can observe its condition. This invites contamination though so should be done with caution.

CLC and MAS both frown on leaving filled epoxy component bottles on bare concrete floors. Reason being that floor will keep the stuff inside bottles from reaching room temps. Cool resin crystallizes over time, and should not be mixed w/hardener without giving it a warm-water bath (while still in its bottle of course!) so those crystals can re-melt before components are dispensed prior to mixing.

Properly stored, epoxy components can last quite a long time without degrading to the point they're unsafe. Disposing of unused components (find something useful to do with 'em! Don't just pitch it!) is best done by combining them according to the manufacturer's instructions in smsll enough quantities that exothermic reaction won't be a fire hazard, then tossing the resulting solid mass into your garbage collection.


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