its a mixture of things to have a compressor able to do the job.
it has to have a big enough tank to hold the air a big enough motor to replace the air.
a small 25ltr or 50ltr compressor tend not to have a regulator fitted so it will always start off pushing out high pressure but as the air is used it drops, it drops down untill the motor cuts in, the motor then has to replace the air that has gone and the air that is being used.
that means that when you start of spraying and have adjusted your gun to the right configuration as it uses the air in the tank the pressure drops and affects the settings you have made on the gun.
the proof is in the pudding, fill your spray gun up with some thinners and set your compressor away untill it switches its self off then start spraying into the air and watch the fan off thinners comming out of the gun, it will reduce in pressure untill the motor kicks in and it will never be as good as when you started so this would effect the quality of spraying that you are doing, to a untrained eye it might look the mutts nuts but to some one who has seen good spray jobs its only a 2/10.
remember as the pressure drops the paint does not have enought pressure behind it to blow it onto the panels so float around there fore needing more paint and causing a lot of dry overspray.
that makes perfect sense and that is exactly what happened last time i tried to spray, :'(
