Shelf Life Of Unopened Epoxy

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Well-Known Member
May 3, 2017
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How long will a two-part unopened container of epoxy maintain it's usability?
I have had some BSI epoxies last 5 years after opening, if one part looks to be really thick, gently warming the bottle in hot water and then mixing carefully will generally restore it to proper consistency.

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I'm just now finishing up a 5 gallon pail of epoxy. I bought it expired on ebay about 12 years ago. I just bought a case of 24 qts of Hysol. I hope it lasts as long.

The more expensive the epoxy is, the shorter the shelf life open or closed! Kurt

I am still using 3 hr Bob Smith/hobby shop epoxy 16 years later. RocketPoxy, for example, lasted just a year or two, just as the manufacturer says. There are logical, chemical explanations for this, but Kurt's theorem does hold true!
Try some of the pricey Cotronics stuff and read the manufacturer's spec sheets. The catalyst starts out as a dilute urine color and sitting on the self if turns
to maple syrup dark, opaque brown.

I bought some run-of-the-mill 30 minute epoxy over 30 years ago from Tower Hobbies for not very much and the left over hardener just completed crystallizing in the bottle. Used it off and on for years.

If you want to use that "stuff" that's good to 500 to 700 degrees F you better have the project set up to build and get 'r done quickly if you want the stuff to be up to manufacturer's spec. Kurt
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[h=2]Storage and shelf life[/h]With proper storage, WEST SYSTEM 105 Epoxy Resin and hardeners should remain usable for many years, especially if the containers are kept closed in order to prevent contamination. Over time, the resin will thicken slightly which, in turn, will require extra care when mixing.Both resin and hardeners should be stored at room temperature. Indeed, if the resin freezes and thaws out many times it can cause crystallisation. If this happens, however, it is a simple matter to dissolve the crystals by warming the resin to 50°C and stirring for a while.
I am just finishing using four litres of West Systems and associated hardener. It would be about seven years old. Resin does not quite pour as easy as before but the shift in viscosity is not huge.