The most responsible way to dispose of old paint or finish cans is when they are empty and dry. I’ve come up with a way to speed the process along. I bought an inexpensive cookie sheet and cooling rack, and I spray the sheet with WD-40. I place the can upside down and let the remaining contents drain through the rack onto the sheet. The can dries quickly once emptied, and after a few days I use a spatula to scrape the dried cookie sheet clean.