Keeping an airbrush clean and well-maintained is very important. In fact, it is recommended that you take apart completely and clean an airbrush once a week when you use it regularly. On a daily basis, clean airbrushes by running white spirit or lacquer thinner through them after use.
Disassemble the airbrush and soak all parts except the air valve in lacquer thinner or white spirit for one hour. The air valve contains a rubber o-ring that may deteriorate when exposed to corrosive chemicals such as paint thinner. Should paint get on the air valve, gently clean it with soap and water. If enamel paint remains, use a cotton swab soaked in white spirit to clean the valve.
Soak cotton swabs, pipe cleaners and a toothbrush in another tray of lacquer or white spirit. Use them to brush all enamel paint from the airbrush parts after soaking. Keep cleaning a part until the tool no longer removes any visible paint. The very tip of the nozzle can be cleaned using a twirled piece of paper towel. Twist the towel to a point, dip it in white spirit and run it through the tip, much like flossing your teeth.
Apply a coating of airbrush lubricant to the needle, threaded surfaces and trigger mechanism. Lubricant helps the paint go through the needle more easily, should there be any dried paint left behind. It's also good to help create a little bit of a seal around areas that are screwed together. Lubricant is not necessary for the internal passages of the airbrush as long as the brush is well cleaned and maintained.
Reassemble the airbrush and polish the outside surface with a soft cloth. Do not use oils or soaps on the outer surface of the brush.
If the airbrush leaks around the o-ring, daub the threads with copper paste or grease to help it seal. Consider replacing the o-ring if the brush continues to leak despite maintenance. Blow out the airbrush with compressed air to remove any fuzz that may get lodged in the passages from the pipe cleaners.