Does epoxy have a limited shelf life?

[Belstain]

I used some devcon 2-ton that had been sitting in a drawer for about 6 months on a damascus neck knife and two days later it is still tacky. Is there anything I can do about this? The knife was pinned together too so removing the scales will not be easy but I don't want to have to worry about the knife holding together. Any suggestions?

 

[R.W.Clark]

No real trick that I know of, just got to bite the bullet and take it apart. Epoxy is only good for 5-6 months after the seal is broken. After that it will do the very thing you describe.

I mark dates on all my bottles to let me know when to discard. Not much of an issue. The large bottles only last me about two months.

 

[Belstain]

Every mistake is a lesson learned. Thanks for the info.

 

[plasmaphase]

If you haven't already taken everything apart, you might want to try applying some heat, e.g., with a hair dryer, if you can do so without hurting the knife. The "hardening" of epoxy resins is a self-sustaining chemical reaction; and in general, chemical reactions are not "off-on" processes. Instead, one would expect a rate of reaction somewhere on the scale of very slow up to very fast. In organic chemistry (epoxies are organic), there is a general rule that increasing the temperature of the components by 10 centigrade degrees (18 farenheit degrees) will double (more or less) the reaction rate. If you can raise the tempreature sufficiently to get the reaction to kick-off at a relatively fast pace, it will probably take care of itself from there and proceed on to completion. Good luck.

 

[Mike Hull]

I dont know about shelf life,but it is very sensitive to temperature,if your shop has extremes of hot and cold,keep it in the house.I have had the exact same thing happen to me with devcon 2 ton,I now keep it in the kitchen cupboard and find the shelf life indefinite.Just pop your knife in a preheated oven 250 deg f,for 1/2-1 hour,and everything will come apart with no problem.Hope this helps a little.

 

[Ed Caffrey]

Most all of the commercial epoxies have a shelf life of 3-6 months once the seal is broken. Another area to look at is the "hold life". This is the duration the material will hold parts together before it starts chemically breaking down. Most epoxies have a 5 year hold life, provided they are not exposed to much UV light. UV will shorten the hold life considerably. As I've talked about before, these are the reasons that I use Accra-Glass from Brownell's. The shelf life is 5 years after the seal is broken, and the hold life is 50 years!

 

[Eric M Ericson]

If you can't heat cure it, you may be able to wash the uncured glue off with vinigar.

 

[FWO]

Try www.westsystem.com for any technical information on epoxy application.

FO

 

[TLM]

Most commercial epoxies have a closed shelf life of 12-24 months and 6-12 months opened. It varies alot I have succesfully used 6 years old epoxies. It's usually the hardener that gets old. Even room temperature with no moisture and no sunlight is best for storage. In the ten years I sold epoxies I met one case of bad hardener and about 200 of wrong mix ratio so the odds are your mix ratio was not correct, on epoxies it generally has to be exactly the one given, there are few ecxeptions. The word epoxy refers to the functional group in the resin, it does not tell anything about the hardener, which can be one of a various lot. I usually use acetone or methyl-ethyl-cetone for cleaning epoxies (not on your skin!!!).

TLM