Solder Shelf Life - 96-Sn/4-Ag

I have some Kester rosin core wire solder (96-Sn/4-Ag) that has exceeded its shelf life. According to Kester's knowledge base, their
Shelf Life Policy statement states that:
"Flux cored solder wire has a limited shelf life determined by the alloy used in the wire. For alloys containing more than70% lead, the shelf life is two years from date of manufacture. Other alloys have a shelf life of three years from date of manufacture."
I would like to know the mechanism of degradation of the alloy.
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Might be simply the flux.
Might be simply the Kester's bank account.
They speak of only the fluxed solder. I suspect it might out-gas or dry out.
If you have any trouble with it wetting I'd snip off several inches and start again. I suspect it isn't through wall migration but end leak.
There are many fluxes as well. I doubt the claim to be general in nature against all fluxes - some of which are organic and some inorganic.
I wouldn't sweat the small stuff. That is quality solder.
That is often used to solder to ceramic.
Martin [ I have 7/8 of a roll in the shop as well ] Mine is 40 years old and still works.]
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