How to Prepare and Repaint Exterior Windows

Preparation

1). Clean the entire window thoroughly. Spraying the window with a hose removes loose dirt and debris. Be cautious of leaks in the window that may allow water inside if using a hose. For more difficult dirt, use a mild detergent mixed with water to scrub it. Get rid of mold with a combination of one part bleach and three parts water. Spray the bleach mixture on the mold and wait for the mold to turn white.
2). Scrape the loose paint from the windows using a sharp putty knife. Remove any loose caulk and glazing from the exterior windows.
3). Sand down the window frame, sill and sash. Use a palm sander to make the job easier and faster. Use a fine sandpaper to smooth all of the wood surfaces. Any rough spots will show up through the final coat of paint if not smoothed properly.
4). Apply a coat of oil-based primer to the windows. Allow the primer to dry fully before proceeding.
5). Caulk any gaps around the window. Apply glazing compound to areas where the glazing was removed. Give the glazing 24 hours to cure.

1). Apply painter's tape to the glass panes to keep them clean during the process. Clean off drips as soon as possible, when they are easiest to remove. Add painter's tape around the outer edge of the trim to protect the siding.
2). Paint the inside edge of the window frame, beginning at the top and working down the frame.
3). Raise the lower sash and lower the upper sash so they are slightly overlapping. Paint the sash that is fully exposed and the surfaces of the inner sash that are visible. Allow the paint to dry, and then switch the positions of the sashes so the remaining portion of the inner sash is visible. Paint that section of the sash.
4). Paint the window sill and casing.
5). Apply paint to the window trim, starting at the top outer edge of the window. Work down the side of the trim. Start back at the top of the window trim to paint the face. Work down the window trim until it is completely covered.