epoxy question

Quick question for the epoxy gurus out there. the plastic ferule seperated off my carbon wing, so i epoxyed back on (ace hardware 5 minute epoxy, mixed in correct proportions, or so i thought). i let it dry for probably 36 hours before using it again. it seemed fine, but yesterday it started to get loose again, and when i pulled it off the epoxy was rubbery and soft.

what did i do wrong? was it just water exposure? incorrect proportions of resin and hardener? lousy epoxy?

i redid it last night, making sure to have the proportions right, and using more epoxy so that there is no room for water to enter under the bottom ring. it’ll get to cure in my hot car for the next 24 hours.


Marine Epoxy
I tend to use Marine Epoxy (often 3M) when I really want to be sure of hold. I sometimes use Marine Goop.

If dealing with not-structural elements (especially mini-cell) I usually use Contact Cement (Weldwood).

I think that many epoxies which are not marine specific may not hold up to regular and repeated soaking in water.

Wrap in Saran Wrap
Or try something similar when applied. Some epoxys do not air cure well.

Could be many things
Epoxy has expiration dates. The 5-minute stuff has a shorter shelf life than longer epoxies. Is it expired? How long was it sitting on the shelf at the hardware store? If you still have the package, you may be able to find either an expiration date, or a manufacture date.

Was it the double-barrel syringe type? As hardener sits around, it gets - well - harder. It’s possible that you didn’t get the proportions right.

I use West epoxy and I no longer use
any of the hardware store brands. I have been disappointed too often by store brands.

I would suspect that relatively small errors in mixing proportions and/or mixing 5 minute ingredients under very humid conditions could contribute to a soft set. As for expiration date for the product, I have had West sitting in my basement for 3-4 years, the pumps in the can, and while the hardener got thicker and reddish in color, the mixed epoxy set up and hardened normally. So, the age issue needn’t apply to all epoxies.

If it was the two syringe stuff…
I am quite surprised that it didn’t harden correctly since the proportions usually come out correct.

I have used that to reglue canoe paddle handles when I shorten one and it has worked fine.

Humidity possibly affecting it ?

Like others; I prefer the West Systems.



mismix, mismix, contamination
My three guess as to imperfect cure:

  1. mismeasured proportions - the only time I’ve ever made “soft” epoxy was a micro batch of less than spoonful units.
  2. I read somewhere that you have to thouroughly mix the resin and hardner, and if you fail, you get a gooey result.
  3. Did you clean your surfaces? Soap and water then alcohol is my recommendation. I think it would affect the bond moreso than the set, but possibly your epoxy got some sort of contaminent in it from your mixing or application tools.


thanks all
i checked the 2nd try today at lunch and it seems good and hard, at least where i can see it. i think i must not have had the mix right last time. i’ll see how it holds up.


5 min. NG … and some actually say
not for immersion … At least go for the 20 minute stuff next time : ) Which you probably will need soon.

West System does have some pretty nice ‘5 minute’ stuff now though and it keeps pretty good.