Is old epoxy okay to use? - RC Groups
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Sep 17, 2011, 01:55 AM
bjaffee's Avatar

Is old epoxy okay to use?

Got some 20 minute Finish Cure that's been sitting around for a long while. The hardener has turned a VERY dark yellowish brown. I've got a test batch setting up right now...assuming it cures okay, is it okay to use? I just want to make sure it doesn't set up more brittle when it gets old.


PS...I'm using it to glass the center section of a wing.
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Sep 17, 2011, 10:49 AM
No fuse too fat
slopeiron's Avatar
I'd say if it kicks your good to go. The West Systems hardener turns dark over time too. But it still works just fine. Just makes brown parts.
Sep 17, 2011, 11:29 AM
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MicroRotors's Avatar
Your test will tell. Sometimes old epoxy doesn't cure and it stays gummy or tacky even though it has set up to a firm state.

My thoughts, ... if in doubt and it's a small quantity, ... replace it, ... if it's a gallon, ... pray.
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Sep 17, 2011, 04:44 PM
jimbo320's Avatar
Good quality epoxy has good shelf life. Just test it and see. If it's good quality will be ok.
Sep 17, 2011, 05:01 PM
bjaffee's Avatar
Thanks guys. My test batch was rock solid by morning today, so I glassed the bottom of the wing root. So far, so good.

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