Paint exterior wood doors using an acrylic paint designed to protect the wood from weather-related damage. Choose a paint that protects against mildew, water stains, dirt and rust. In addition to the paint, outdoor wood painting requires a sanding implement, paint scraper, sponge or steel wool for cleaning, filler and a putty knife.
Clean the door
Clean the outside of the door with soap and water on a sponge to remove any loose dirt.
Remove old paint coats
Using a paint scraper or steel wool, remove as much of the old paint as possible. If desired, use a paint remover to completely remove old coats.
Sand down door
Using sand paper or a sander, sand down any remaining paint to smooth out the wood. Clean off any wood dust.
Fill in cracks, indentations and nicks
Using a wood filler, painter's caulk or putty, fill in any uneven areas. Sand again if necessary.
Apply the primer
Using a paint roller, cover the entire surface with primer. Be careful not to drip. For decorative areas on the door, use a brush to apply the primer. Let the primer dry.
Roll on paint
Use a roller to apply the first coat of paint. After the first coat dries, apply a second coat if necessary.
Apply protective finish
If desired, cover the dried final coat with a protective finish made for outdoor wooden surfaces.