On Mon, 15 Oct 2012 12:13:47 -0400, "Existential Angst"
wrote:


Assuming they are still dry, of course. A local home center guy said yes,
prolonged exposure to air renders it unusable.
How old is old? How to test? My own little spot tests (small mounds on a
board) are really crumbly, but I haven't compared it to fresh stuff yet.

Open bags go bad pretty fast, maybe a year or two in temperate
climates., and that includes even bags where the open end is rolled
down. Don't know about keeping it in buckets as Dufus mentioned.
I throw it away if it any of the powder has hardened. It's cheap
enough, and if it doesn't bond right you've got a mess and wasted a
lot of labor.