the below YouTube video guy uses a modified tire valve to put compressed air into a can. He said about 90-100 psi was max.
www.youtube.com/watch?v=KWIL_jhk-y8 Propellant has no air in it so the paint does not start to oxidize. Air will start that process.
After using a rattle can, I always take off the nozzle, spray acetone or Goof-Off thru it until it runs clean. I never turn the can over and spray. then carefully put the nozzle back on, careful not to push too hard and release more spray. I have probably 20-30 rattle cans and they all work until dry. Some 10 yrs old.
