Epoxy not curing — advice please!

[ThirstyBarbarian]

I’ve laid in some epoxy fillets, and several hours later they don’t even seem to be starting to cure. This is some epoxy I bought and used in late April or May, and it worked fine. One part was stored with a cap screwed on and the other part I lost the screw cap, and used the little push-on cap that goes on the squirt top. I assume that was not a good thing and the stuff went bad.

What do I do now? Obviously I need to remove the goopy fillets, but what happens next? This is a repair to a cardboard and wood Warlock, so some of the bad epoxy will have soaked into the materials. Is that going to be ok? If I buy the same brand and mix up a good batch and replace the fillets, will the good materials cure the bad ones that have soaked into the wood and cardboard?

Also, what is the best way to clean up the bad stuff? I’ll wipe away what I can, but if I needs to really clean it, should I use alcohol?

Any advice is appreciated! Thanks!

 

[Estesbasher]

Was the hardener the one with the lost cap? When I've had this happen it seems like the mixing ratio was way off. You just might have to scrape off the fin filets and clean it with alcohol. Then I'd let it sit for a few days before trying it again. With some new epoxy.

 

[ThirstyBarbarian]

Yes, I think it’s the hardener.

Your repair idea is what I figured too — Scrape it off and clean with alcohol. Unfortunately, I don’t have a lot of time to let it dry. I need to repair it this week and be ready to pack the rocket up by Thursday. And I’d like to repaint over the repairs. Hopefully I can get it done in time!

 

[Estesbasher]

Spend a few minutes with a hair dryer or heat gun after you clean it up. If you use a heat gun try not to heat it up too much.

 

[Mike Howie]

When I have epoxy that won't dry, I try a hair drier set to hot. Yes, while still hot the epoxy is soft, but when it cools down many times the epoxy is good. Warning, don't get it too hot, or you could deform your bt.

 

[ChrisAttebery]

Yep, try gently warming it with a hair drier or heat gun. Wait 15-30 minutes and check it again. If it hasn't cured by then start scraping.

Good luck!

 

[ThirstyBarbarian]

Update -- I ran out to time to scrape it out that evening, so I left it overnight. The next morning it hardened enough that it was going to be a real pain to get it out, but it still wasn't really cured. I left it another night and it finally hardened. In the meantime, I bought another batch of the same stuff and did some of the other fillets on the rocket. Eventually both sets firmed up enough that they were hard and "dry" enough to be sandable, so I guess it's going to be OK. I painted the rocket, and it looks like there is some slight orange peel over the fillets made with the older epoxy, so maybe there is still something working in there, but the fin feels really solid. I won't be flying it until Friday or Saturday, so that will be total of 6 or 7 days.

 

[ThirstyBarbarian]

Thanks everyone who replied!