I've mixed 2 batches of fiberglass resin EXACTLY according to the directions on the can and neither one of them will harden. Does figerglass resin go bad? It's been on the shelf for maybe a year

 

I'm no expert, maybe a professional can chime in with shelf life and storage temperature numbers, but
I have had some resin go bad from sitting out in the garage. I don't know if it froze or was just old
But it certainly was no good when tried to use it. Looked weird, wouldn't setup.
It was admittedly, the cheap bondo brand stuff.

 

They should have a shelf life of a few years, do you have the correct hardner? Is it freezing cold? Perhaps try putting some heat lamps on it.

 

It's the hardner that came with the can. Temp is in the 50's, maybe even 60 when I did it. I just went and bought a new can of resin/harner, will try that...and the heat lamps too.

 

I've never had a problem and I've never once measured right. I've used resin that has been open for a few years with no problem. The most important thing in my experience is to buy professional quality supplies and when in doubt us more hardener.

 

Fiberglass resin does not go bad, at least not in a year. The instructions on the back are usually a little bit conservative, just test a smaller amount of resin with more hardener to see if things improve and then adjust accordingly.

 

Heat will work better then adding more hardener. Is it poly or epoxy?

 

I would add more hardner, I do alot of fiberglass work and have never had a problem with it not hardening. Add the hardener and then mix really well and apply to what you need.

 

Well, after careful consideration on this I'd have to say the directions for this resin SUCK ***!!! It states to add "14 drops of hardener for every ounce of resin" What kind of ******* directions are those? Why not say "add 2 cc's of hardener" or some real quantity instead of the 14 drops bullshit? I did finally got a test batch to cure properly in around 12 hours...had to add about 3 times as much hardener as the directions say to add, but it cured hard and is not the least bit sticky. It makes me curious if something IS wrong with the resin though, that I had to add that much hardener. I'd sure hate to screw this project up to the point I can't recover.

 

Resin doesn't really go bad, I've used resin after years of sitting (read being "discovered") on the shelf.

Hardener has a shelf life of about a year, toss the hardener.

a "drop" is an actual measurement; IIRC it is like 50 microliters
I don't think most people have a reusable measuring cup/syringe that shows that small of a designation. So the basic "poke hole, drop fourteen drops per ounce" suffices since there is room for error

 

The MEK(hardener) will go flat and not work as well. The temp you're working in is pretty low too. All the MEK does is start a reaction in the resin, its the catalyst, the hardener is already in the resin. You don't need to heat the whole part if you are trying to help "light it off". If you just throw some heat on one corner it will creep through the whole part. Resin will go bad eventually, it all depends on the temps it lives in on the shelf. Down here in Fla it will get crystals in under 6 months during the summer.

 

1cc is 20 drops.

 

No crystals, resin looks normal. Thumbs up on the 20 drops = 1cc. Stupid question, but how much of a fire hazard are the fumes? The only heat I have in my garage is a kerosene heater and I was afraid to light it. Don't want to have an explosion...would kind of ruin the project if you know what I mean.

 

Hey i don't know if someone has already answered your questions here but i used to work with kevlar, fiberglass and carbon fiber a few years ago.
Usually the company i was working for would consider the fibers and resins to have a shelf life of one year.
But a big tip you may not be aware of is when making the resin and it exotherms(gets hot) that reduces the integrity of the resin and will make it loose its structure.
The resin should be fine especially if you use it in smaller amounts and be sure to use it on very clean fiberglass in a dust-free environment.
good luck!