Slow Curing Epoxy

I just noticed that an area of epoxy in the forward compartment of my boat is STILL a little tacky, 2 days after application. My work area is just about 60 degrees, probably the minimum for epoxy. My other epoxy applications are curing a little slower than I read about, but they DO cure. I'm pretty sure that I didn't make any gross errors in mixing. Will the epoxy eventually cure at lower temperatures? I have just placed an oil-filled radiator a few feet away from the problem area for overnight. How long should I wait before scraping it off and re-doing (the last resort)?


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RE: Slow Curing Epoxy

Hi Jim,

The temp in your shop is a bit low for regular cure time.  At 72 f it will take about 5 days for the exoxy to  fully cure.  At 60 f it will take more than double for it to reach full cure.  If your core is cool when you heat up the room, it will need to reach the same temp before the epoxy will push to the rate you would expect.  Just hope you didn't make a ratio mistake.

For every ten degrees lower, it will double the cure, and 10 degrees warmer will make it set twice as fast, almost. This type of epoxy melts at about 140 f, so making it too warm on the surface, like with a heat lamp, will make it seem tacky until it cools awhile, just don't try to heat it too soon or air will escape from the wood and cause bubbles in the set.

You can use MAS Flag resin and medium hardner to get overnight sanding of fillets or glue joints if your temp is up to about 75+ for the full time. Well, I should day 24 hours. Flag is not terrific for coating since it is a bit thicker than standard resin, but it is really nice to use for gluing decks, bulkheads with a little filler, or panels, but coat the panel first, then lay on the small piece of glass.

Hope this helps.


RE: Slow Curing Epoxy

Thanks Dirk. I now thiink that I did make a mixing error, and I'll be cleaning it up & redoing.

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