I'm not quite sure how much drywall mud I'll be using for my upcoming project so I'm planning to buy a box of it. Assuming that I have some left over, is there a technique for not wasting it? Will it last for awhile if I make sure to tie up the bag again and close the box lid? Or should I assume that it'll only last for a short time after I initially open the box.
Also, what's the shelf life for drywall mud? Should I only buy as much as I think I need? Or if I found a good deal, will it keep for awhile (for use with other projects later)?