Just curious...does mud really have a "shelf life"? I've got a 3+ year old 5 gallon tub, 3/4 full, stored in the basement. Is it still good? Thanks
If there is a little bit of water on it it should be okay if it was kept cool but I would not use it myself for any finished coats.
I always keep a piece of saran wrap over the surface of mine, and keep the sides scaped down so they don't get hard...
Mud has a shelf life of 9 months. After that, it will spoil and mold. Hence the bad smell when opened.