You should be aware that moisture and oil can get into the air line and spray gun from your air compressor and mess up your work. This is one of the disadvantages of using an air compressor instead of a turbine to supply air. There’s no possibility of moisture or oil being transferred from a turbine.
To reduce the possibility of moisture getting into the air ine, drain the compressor’s tank on a regular basis. Oil usually enters the system through deteriorated gasket seals, so you shouldn’t have an oil problem unless the compressor is old.
To deal with both problems, you can install filters like those shown in the accompanying picture. There are many varieties of filters, including filters that can be hooked directly to the hose, just before it attaches to the spray gun.
If your finish supplier doesn’t carry filters, try an auto-body supply store.