I had to reinforce a firewall with carbon fiber and epoxy. I used an old bottle of 5-minute epoxy and hardender. It's been almost 6 days and it is still quite sticky, even running very slowly at places. Is this because the epoxy and/or hardener are too old? If not, why? Regardless of the cause, what do I do? Do I have to remove what is there? If so, it will be a mess, if at all possible. Any tips would be extremely welcome...

Thank you in advance.

My guess is that you didn't mix it right!

Because you are working in a critical location, I'd remove the old stuff and start over by brushing denatured alcohol over it, whilst swabbing up the mess with a paper towel. You should be able to get most of it off this way, then reapply with a fresh coat of epoxy. Any remaining first layer should cure with a properly mixed second layer.

[img]i/expressions/face-icon-small-happy.gif[/img]


Yeah what ****zuan said

and go buy some new stuff !!!

JB [img]i/expressions/face-icon-small-smile.gif[/img]

Probably a bad mixing. However, it is not a good idea to use 5 minute epoxy where high strength is required (like on a firewall) as it is to easy to do it wrong; a bad mix, a proper mix starting to cure befor application is complete etc. Also, the slower epoxy are quite a bit stronger for two or more reasons; two of them being that the slower epoxies penetrate more and the resulting molecular chain of the cured epoxy is longer thus stronger.

Epoxy will age and deteriorate and after a certain period there is no good or bad mix. There just isn't any mix that will work. Get some new stuff. Remove the old from your firewall with denatured alcohol as much as you can. The removal is very important because the old uncured junk will still be old uncured junk under the new
material. Rodney is certainly correct about the difference between 5 min. & 30 min. epoxy. You don't have to wait to get more epoxy by mail order. ACE hardware as well as any other complete hardware store probably has something you can use. Just check the cure time on the package before you take it home.

For the future I have not had much luck with hobby store epoxy, aircraft and marine grade epoxy’s work great for me. Great Planes makes pre measured epoxy cups; it is the best way to get the exact mix.

best epoxy i had, you pushed a plunger and it forced out equal amounts of resin and hardener[img]i/expressions/face-icon-small-smile.gif[/img]. best place I found to keep it was in the fridge stops it denaturing[img]i/expressions/face-icon-small-blush.gif[/img]