Cleaning

• Generating a flawless painted finish on slick metal is difficult enough without having to worry about poor adhesion and sagging due to unseen oils, grease and dirt. Before you even think about applying any type of coating to a metal surface, thoroughly clean it, using a water-based degreasing cleanser and a pressure washer.
  
  

Masking

• Even the best professional painter cannot keep paint overspray from flowing onto adjacent surfaces. Before you begin the application process, thoroughly mask off those areas running adjacent to the metal. Use masking paper, professional painter's tape and dense canvas drop cloths to cover anything within three feet of the metallic surface. If you are painting an exterior metal surface, wait for a warm day free from wind. Be sure no automobiles are parked nearby, as even a subtle gust of wind can cause paint overspray to travel a considerable distance.
  
  

Priming

• No type of paint will adhere to bare metallic surfaces. If you spray paint directly over under-prepared metal, peeling will begin within weeks. Unfortunately, most types of spray primer cannot bond to nonporous, durable metal. To generate better adhesion, spray a coat of galvanized metal-etching primer onto the metallic surface. If the metal is located outdoors, use an etching primer that has rust-inhibitive properties.
  
  

Painting

• Once you've prepared the metal, you may apply a quality spray paint. Choose a particular painted finish depending on the location and role of the metal surface. Use acrylic latex paint on exterior metal siding. If the metal is subject to duress, apply an enamel.
  
  

Application

• Because metal is slick, it's prone to sagging and runs. For sharp, attractive results, maintain 8 inches between spray can nozzles and the metallic surface. If you are using an electric- or gas-powered spray rig, maintain 18 inches between the metal and spray tip.