I have a cheap Craftsman paint gun that came with my compressor that I'm planning to use for the primer. I figure I can get away with it being that the primer is going to be blocked after applying anyway. It's a siphon feed type gun with the can on the bottem. My question is....how long will the paint last in the gun after mixing? Do I have to mix up only what I need at a time or can I mix up a whole can and then get away with just cleaning the top part of the gun after each application and just let the paint sit in there until I need to use it again? Kinda like a regular spray can where the paint stays liquid inside until you need it.

Thanks

Depends on the primer you use.The old laquer prime would stay good in the gun for a long time.We would fill the gun up and just stir it up and shoot it when it was needed and when it was empty fill it back up. Newer 2k primer (that you should be using) only has a potlife of 45 minutes or so,so you would need to clean the gun out after every use. If you dont it will harden up in the gun.

When I was painting industrial equipment we most always cleaned our guns and paint pots out after each use unless we were spraying a single component, slower drying oil based paint.

Keeping the equipment clean and free of clogs is very important!