JEM Watercraft

Question: How long do you wait on a sticky epoxy before deciding to sand it off and start over? I am at around 40 hours now and the last batch is still tacky and leaves fingerprints everywhere you touch it. I know i measured right. The only other possibility is the minor cold front that blew in a few days ago. Low temps dropped to the 60's, highs are still right at 80.

40 hours should be more than enough even for slow cure.

If you have a heat gun or hair drier, CAREFULLY warm a test area so it's very warm to the touch, let it sit for about an hour, and see if it's still tacky. If so, you'll have to scrape it off.

You might want to try a small test batch of epoxy on scrap wood again. If you're 100% sure of the mix procedure and it's still tacky, you should contact the place you bought it from.

I am almost through the first gallon and this is the only batch to do this. I know it isn't a manufacture issue. I did go a little thick on this coat.
Might that be the problem?

Perhaps. Get some heat on it and see it that helps.

As a precaution, I'd get a fresh mixing cup and applicator (or a good wipe down of both with acetone). Just in case you got something in there the epoxy didn't like.

Not even the slightest chance that you put in too much hardener?
Has your epoxy mix cured successfully on previous parts of the boat?
If you're using slow hardener, In those 40 hours, how many hours were in the 60s?

All previous mixes cured within 6-8hrs. Something just wasn't right with this batch. Overnight with 1000watt work light still yielded sticky mess. I tried the heat gun too. No luck. I attempted to scrape it off but I am using SS@G method and the WRC just did not want to turn loose of all of that sticky epoxy. I tossed the affected parts and planed some new strips.

Dang. But at least you caught it now.