If you don't clean your spray can nozzles after each you, then will become clogged. A clogged spray can nozzle may not release any paint at all, or the paint may come out in a coarser mist leading to clumps of paint and a finish that looks bad. To keep your spray paint nozzles from getting clogged, after every use turn the can upside down and spray until no more paint comes out. This will clear all of the paint from the nozzle and lead to better finishes for your spray paint projects.