Epoxy--new vs old?

[Beemerider]

Does 2-part epoxy have a shelf life? I've got some that's a few yrs old but unused. Still flows out of the bottles although the hardener half seems thicker than I remember it being. Any compromise in performance or strength vs a fresh set?

[kyleservicetech]

Originally Posted by Beemerider

Does 2-part epoxy have a shelf life? I've got some that's a few yrs old but unused. Still flows out of the bottles although the hardener half seems thicker than I remember it being. Any compromise in performance or strength vs a fresh set?

Yeah
I've run across epoxy getting old and thicker than normal. For important glue joints, methinks it's safer to just replace it with new stuff.

(My CA and epoxy bottles are marked with the date when they were opened. CA definitely has a shelf life after being opened.)

[vonveska]

I think there is shelf life on epoxy products. From my experience epoxy older then one year tends to heat up when mixed and hardens quickly, resulting in brittle joints. I use few years old laminating epoxy and I dilute it with few drops of methyl to prevent quick setting. The strength is probably not 100% but still OK for non critical applications.

[Rodneh]

I am not sure about strength but I have had some epoxies that were over 20 years old (still have some of Hobby Poxy) and they still worked well. The Hobby Poxy (no longer available) that I still have is their "thicksotropic sp?" and it still works well. I also have several cans of their epoxy paints and frequently use them (I think that the presently available Klass Kote is the same product) with no change in how well they work.

[Beemerider]

Thanks for the replies. I have some new epoxy as well so I think I'll take Kyle's advice and relegate the older stuff to less critical stuff. I keep my all my ca products in an old coffee can with the lid on. Seems to help although I don't buy big bottles of any of this because I know it'll go bad before I can use it all.

[solentlife]

Epoxy is quite tolerant of age .... but yes it does degrade with age but in our use ? The Epoxy is far stronger than we need.

The resin that does age badly though is Polyester - the Glass Fibre resin ... it often darkens with age ... cures poorly .... etc.

Nigel

[cyclops2]

I find that a NON-TIGHT lid is a fast death for any type of glue / adhesive. OR even forgetting to close it for a day or 2. Gone.

[Beemerider]

Originally Posted by cyclops2

I find that a NON-TIGHT lid is a fast death for any type of glue / adhesive. OR even forgetting to close it for a day or 2. Gone.

Seems slightly thick ca (medium) gets real thick quickly without careful storage. I've lightly heated the bottle (both ca and epoxy) in a microwave or careful application of a heat gun to get it thin enough to use after it has a little age on it. I only buy the very small bottles at a time as well unless I know it will be used quickly (seems I don't do anything quickly anymore except falling asleep!)

I try to keep all bottles tightly capped and also put those bottles in a coffee can with the lid on.