Epoxy not getting hard

It has been 36 hours and my last coat of epoxy is not getting hard (I can scratch it of with my figernails) in some spots, particularly where there is a thick drip I failed to cleanup. Unless someone thinks it will harden after a few more hours or days, or there is a magic hardener I can spray on, what's the best way to remove this failure? Scraping and sanding?

BTW - my kit shipped with MAS mixig cups which I burned through. I ordered new oens and CLS shipped a different brand, Encore Plastics, I am not a fan of these and I keep second guessing - are the measurements off?

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RE: Epoxy not getting hard

Someone more experienced than me will be along shortly I suspect, but in my experience  this happens to most of us at some stage. I found that a hot air gun and scraper was  the easiest way to remove the uncured epoxy. Watch for fumes - take sensible precautions. Clean up afterward with meths/ denatured alcohol and sand lightly beofre starting again. It happened to me I think because I lost count of the pump strokes I was doing  in mixing up large batches. I no longer trust the pumps - I bought a cheap set of digital scales and weigh everything - I think there is less room for error that way. Onward and upwards.




RE: Epoxy not getting hard

   LTL is giving good advice. It's amazing what a little heat can do to soften epoxy. I once epoxied two pieces together backwards. I used my wife's hair blower to heat up the area and was able to strip off the fiberglass and epoxy relatively easily.

I've found MAS epoxy to be pretty forgiving about inexact measurement, but it does like to be thoroughly mixed. Every molecule of resin needs contact with a molecule of hardener for the chemical hardening to take place.

Unless it's a very tiny area in an out-of-the-way location, strip it off with a heat gun and start over.

RE: Epoxy not getting hard

We ended up measuring into marked cups to eliminate accidental miscounting or uneven pressure of the pump strokes.  Tedious, but it seemed to help.  We had a whole stack of restaurant food storage containers we used for mixing, and we took one and turned it into a graduated cylinder by measuring water into it and marking with a Sharpie, which we then used as a template to mark the identical ones for mixing for the specific volumes as desired.  Made us feel very scientific, it did.  <;-)


RE: Epoxy not getting hard

   that sounds like the classic - not mixed well problem... watch a few videos of a master and compare to your process of mixing.


RE: Epoxy not getting hard

 Not an answer but a question from a beginner. You said you blew thru your measured cups. Do you not clean and reuse them? I’ve just glued my panels together and cleaned out my cup with acetone and hope to keep using.  

RE: Epoxy not getting hard

   I just went through this. See my post titled 'tacky epoxy'. I waited 10 days and still didnt harden. There is no magic spray. If its soft all over rather than a few spots its probably incorrect mix ratio. Stripping it off isnt hard and only takes a few hours. If you want details let me know. Theres also a YouTube of it being done called 'refinishing a strip planked boat' that is helpful.

RE: Epoxy not getting hard

   @Wolfe1959 "Blew through" them was a poor choice of words.  I used each one as much as I could, but should probably have used acetone to clean them out rather than wrestle out the remaining bits of epoxy from the previous pour which is hard on the cups and makes them crack.

I ordered more MAS cups directly from MAS. Also picked up a tube of Woodzilla for greater likelihood of success on my remaining fillets. 

As for my problem of uncured epoxy, 60 grit sandpaper stripped it all off effectively and I am making progress, slowly but slowly, toward my (hopeful) launch date of 8/1.




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