Metal garage doors are sturdy and do not require a lot of maintenance. They do need a good coat of paint to protect the metal from the elements. Exposed bare metal can rust. Rust weakens the structure of the metal. When paint chips, scratches or wears off a metal garage door, it is time for a new paint job. Another good time to paint the garage door is when the exterior of the house has been painted a new color. The garage door color should look nice next to the exterior house color. With a good paint job, a metal garage door looks attractive and will last a long time.
Spray off the metal garage door, using a hose with a spray attachment nozzle, to clean away dirt and debris.
A primer base coat makes the final color coat stick better to the garage door. Open a can of acrylic paint that is made for outdoor use. Stir the paint using a long stick to mix thoroughly. Pour the paint into the spray gun. Acrylic paint is a good choice for garage doors, because the paint is flexible and will bend instead of chip off during garage door movement. This is important because garage doors move often during normal use, when they are opened and closed.
Paint the color coat on the garage door using the spray gun. Only apply a thin coat of paint. The paint should be fully dry in 24 hours. If desired, paint a second coat of paint on the garage door.