Epoxy hardening time .

[Len Biglin]

Hi everyone , I have been using West System 105 for years , but lately it doesn't harden ! The weather is cool but after a week it is still not real hard . Is there a use-by date ? which is not stated on the bottles ? Is it cool weather ? Will it harden at all ? Can it be removed from a joint if it wont harden? Will fresh epoxy stimulate it to harden if introduced to the joint ? Thanks Len

[Jeff Highland]

That good news Len!

[Peter Laine]

I've had old resin & hardener fail to react, but most of the time it's old sticky pumps that are the culprit.

For small amounts you can measure by weight on a gram scale.      206 is 5:1 by weight.   

    Just to add a small bit of info, Epoxy cures by molecular cross linking, it is very important to have the proper ratio or you will end up with extra resin or hardener molecules, the resulting resin is rubbery or won't go off, certainly does not have the physicals of properly mixed resin.

 When I used epoxy up in  Mass, during the winter I made a base with a light bulb that kept the resin & hardener thin enough to pump

[Len Biglin]

Well I got the old resin and mixed in some new hardener , it worked fine , so Im saying the hardener goes weak over time ( 4 or 5 years) in my case .