Storing two part Epoxy

Completed a repair on the old beater boat over the Winter and only used half of the G/flex in 4 oz bottles. Whats the best way to store 2 part epoxy for future use?

So far it’s holding well on a poly kayak hull.

In tighly closed bottles
Covered in saw dust and spiderwebs.

in general
In general, the West Epoxy has great shelf life. As advised by the makers of West Systems, I’ve stored my epoxy for years in the can, with the pumps installed. Temps range from 0 to 80 F, and they perform fine.

You’ll notice that the hardener turns a caramel color after a while, and I called Gougon (sp) Bros. when I first had that happen, and they said it’s normal and doesn’t affect performance at all.

I don’t have any experience with G-flex though, so probably your best bet is to check with Gougon to see what they recommend.

I have the large G-flex bottles, tightly
sealed. I notice that one bottle has lost volume perhaps indicating that some constituent is changing or excaping through the poly containers. However I’m not at all worried about G-flex lasting, because its mix range is less sensitive than that for 105/205.

Based on a West discussion of aging of 105/205, the 105 will thicken slightly over 5 years. The 205 hardener will darken considerably, and will thicken a bit, but I also have found that West several years old will meter and harden just fine.

But unless one likes the reddish mahogany color produced by mixing old 205, one might want to buy a fresh can. Another issue for aging 205 is that it produces a gas that can drive the resin out through the pump. Very messy, and it’s the hardener that is more likely to aggravate those of us with epoxy sensitivity.

temp change?
I’d guess that your bottle shrank because it was warmer when you sealed it. That’s probably the simplest explanation.

In the proverbial cool dry place.
The hardener will take up moisture if left in a damp area over time. Even sealed in the can. Resin too but not noticeable like the hardener … This will effect cure and overall strength.

Nate, I’ve seen the effect not just with
G-flex, but also with 205. It may take up moisture like Pat says, I don’t know. But the hypothesis of different temperatures when it is stored doesn’t wash. Those bottles have been sitting on my dresser, and I occasionally release the hardener cap to relieve its slightly collapsed appearance. They’re always at the same temperature.

In the dark, in a sealed drum.
The B part of epoxy - what some people call the hardener, is very nasty stuff. Keep it where kids and animals can’t get to it and store it where it is cool and closed to oxygen and moisture. I have a plastic drum with a screw lid where I store my epoxy chemicals, microballoons etc at home.


Ryan L.

Keep them cool but not too cold
Store with caps screwed on tight. It’s a good idea to clean off any residues on the outsides of the bottles, too.

West Systems recommends keeping the bottles stored no colder than 50 degrees F. If you let them get colder than that, eventually the resin part turns cloudy white. This is harmless. It does not change the chemical reactions of the epoxy and can be cleared up by warming the bottle in a pan of water (see directions from manufacturer for heating temp). This happened to a bottle of mine, and I called West asking if it was similar to water becoming ice. They said yes, the resin was still good.

Thanks for the opinions
There have been some posts about freezing Aqua seal to keep it in usable condition but it looks like that would not be the case with 2 part epoxy.

air is the enemy
First, epoxy won’t go bad. Hardeners get darker over time and the resin can crystalize. You just heat it and the crystals dissolve. Ideally, you would like to store it in jars with the least amount of air, in a dark place without too much humidity. But most people put the jug away and that’s that.