GelCoat shelf life

Finally got Number 1 sons’ stuff out of the boat and lawn mower room(which my bride insists on calling a garage). I had beat up my Jensen pretty badly on the 70 miler, so I figured it was time to re gelcoat the scrapes, dings and dangs on her. I pulled out a can of sealed gel coat that I had bought 3-4 years ago for some minor repair then. I could not get the lid off, even with channel locks and Number 2 sons’ help. So I just cut the can open and discovered that even though the can had been tightly sealed, and not catalyzed it had crystalized to a solid. It was a bit of surprise since I had thought it would stay fluid till I catalized it with MEK peroxide.

Now I know why they only sent me a fraction of a pint for my repairs. I wonder if I should have stored it in the refridgerator?

gelcoat, canned polyester resin, and
vinylester resin such as you might buy from John Sweet, is “promoted” so that it will harden when the MEKP catalyst is added. Adding the promoting substance also means that these resins will harden by themselves with time.

Cool storage helps, and way back when I used to pick up vinylester from Noah in NC, I used a super clean glass gallon bottle on Vladimir Vanha’s advice. He said the resin might last longer without gelling in a clean glass container.

I have found that West Epoxy has a shelf life of over five years before the cans are opened, and over three years after opening the cans and letting the metering pumps sit in them. A good reason to find a way to fake gelcoat repairs with epoxy.

Shelf life varies
The Evercoat “One Step Finish Gel Coat” I use for repair work has a rated shelf life of 6 months, but I’ve got some that’s over two years old and it’s still good. Refrigerating gelcoat helps to extend the shelf life, but I suspect that this particular product is formulated so it won’t cure in the can very quickly. That makes sense for a product that’s designed for repair use, since it’s quite likely that the entire can will not be used at one shot.

Interesting point Brian…never thought
of that.

Just used the last of a gallon can of white that was three years old… did not really ever open it unless it was to use for molds … always made sure I stirred it up all the way and put lid back on it.

Just gotta’ keep it sealed and away from heat.

Never tried it but heard once of pouring just enough acetone to cover the top surface of material before sealing up.

Some colors do not last very long at all.

Black being the worst IMO.

Even if the stuff is questionably thick one can usually bring it back to life by mixing with a little acetone.