Most of us have cans of spray paint in our garages. You may pick up 1 or 2 a year becaue they are fast and convient. So acouple of years go by and you need some paint so you get the can and it doesn't work!! I got 1 can that I know is at least 10yrs old and it still works fine. I would say for the old can it around a %75 failure rate. Yes..I turn the cans upside down to clear it. I'M SICK OF IT!!