Exterior fiberglass doors that are constantly exposed to the weather often have a cracked or flaked top coat finish. To improve the appearance of your fiberglass doors, DoItYourself recommends applying a new topcoat finish. Prepare painter's tape, cloths, plastic sheets, paintbrushes, primer, stain and clear topcoat.
Before refinishing your exterior door, remove door knobs, doorbells, knockers, letter boxes and other door furniture. Cover hinges and the edges of windows using painter's tape. You can also use painters tape to cover glass with plastic or newspaper. Lay some newspaper or sheets around the door to protect your floor from stain and topcoat.
Get rid of dirt and debris by wiping the door thoroughly with a sponge that is dampened with liquid soap. Scrub dirty areas, as dirt that gets trapped in the stain will become noticeable after drying. Wash the door with water, and dry it off with a towel, or allow it to dry naturally.
Wear a mask and gloves when refinishing your door, and leave the windows wide open. Add a new layer of paint or stain, and leave it for 48 hours.
Cover less than 1 inch of the brush with topcoat, taking care not to saturate the brush. Apply the topcoat thinly with long, regular movements, starting at the top of the door and working down slowly. Apply up to four coats of finish, and leave it to dry.