I have about one-half of a 5 gallon pail of Anchorseal that is several years old. Purchasing this was a good decision and great value. The stuff goes a long way and keeps well. Well.......it keeps well, sorta. I had about a 1/4 full plastic coffee can sitting for use that also had not been used in a couple years. Yesterday, I went to use the coffee can supply and it was hardened. Wasted. Not happy time for super-cheapo me. Apparently the snap on cap for the plastic coffee can (Folgers) was not tight enough to protect the Anchoseal. The contents of the 5 gal. bucket is still just fine. Lesson learned is to preserve Anchorseal, keep in a well sealed container.