Does fiberglass resin or hardener have shelf life?

Does the resin, hardener, or both have a shelf life?

My problem (I've done it twice with the same result) is that the mixture does not harden, just stays gooey. When I used the same materials last year it worked fine.

I just went out and bought a tube of hardener, but thought I'd check here because if it's the resin instead and I go through this a third time, Imma gonna freak out.

 

i've used stored resin without any problems.

 

Suspect hardener has more volatiles in it, and is smaller volume to start with, so is more likely to go off with age, especially if opened, than resin.

I've used some real nasty looking resin (blobs, etc. ) in a pinch with fresh hardener and it worked ok, considering.

Getting amount of hardener to resin right is important too: you can't just dump in some hardener and hope for the best.

Maybe try a one ounce test batch to see how/if it sets up before you smear it all over everything?

 

Thanks for the replies, it was the hardener (MEKP) that went bad.

The typical answer I found on the internet (briefly searching) was that opened hardener will last about 6 months. It was at least a year since I used mine. Nothing found about resin shelf life.

 

Both the resin and the hardener have shelf lifes. They vary depending on the type (polyester, vinylester, etc) and the manufacturer.

I do a lot of fiberglass fabrication and have noticed the difference between a batch that is new versus a batch that is older. Older batches are less forgiving on the resin to hardener mix ratios, don't seem to be as workable, and cure at unpredictable rates for a given temperature. I've never really used resin that I would call really old (more than 12 months old).

A lot of manufacturers/suppliers recommend not using resin if its older than 6 months. This may be nothing more than a marketing ploy....then again, it may be because the chemical properties change enough over time to effect the integrity of the mixture..... (don't really know for sure as I am not a chemist).

I don't generally have resin around long enough for it to age that much without being used, but as a guideline for myself, if its older than a year I don't use it......... your mileage may vary.....

 

i've always gone with the guideline of 90 days and pitch it for resin. That's what i was taught and that's what i go with. Check out the guys at Select Products. they make some SWEET stuff.