Another thing that may happen is if you leave a rattle can sitting nozzle side up for a couple of years the heavy solids in the paint will sink to the bottom...right where the pickup tube is. Then, no matter how hard or how long you shake the can when you start spraying, you will get just a wee dribble as the pickup tube opening and everything above it has become clogged since you just pushed the heavy stuff up through it. I wonder if this would work to free up situations like that?
Yes, I know...it would be sensible to store all old spray cans upside down (so the solvents would all be at the top), but I never remember to do that.
