Spray the door with a wood cleansing spray evenly. Swab down the doors with soft cloths and allow them to air dry.
Attach a piece of 100-grit sandpaper to the bottom of an iron shaped palm sander. Use the tip of the sander to sand the slats of the door and the entire sander to sand the frame. Repeat with 220-grit sandpaper. Run a handheld vacuum across the surface area of the door, sucking up all the dust from sanding.
Shake your can of spray on stain for one minute. Spray on the stain evenly, making back and forth movements with your can. Tilt the can to get the stain into all the crevices of the slats and the corners of the frame of the door. Allow the stain to penetrate for 20 minutes and then wipe off the excess with lint-free cloths. Repeat this once or twice.
Spray a light mist of clear polyurethane over the door. Hold the can 8 inches from the door and move it back and forth evenly, until you cover the entire door. Allow it 24 hours to dry.