How to Paint a Window Shelf

Dismount the window shelf from the wall by unfastening the angle brackets with a screwdriver.

Combine 1 part trisodium phosphate (TSP) with 3 parts warm water in a bucket. Clean the window shelf with the mixture with the sponge, then rinse with plain water and let air dry.

Fill any indentations or holes in the window shelf with wood filler and the putty knife. Let the wood filler dry for 30 to 45 minutes or as long as recommended by the manufacturer.

Gently sand the window shelf with medium-grit sandpaper, abrading the wood and sanding away most or all of the original paint. Wipe down the window shelf with a tack cloth to remove all the dust from sanding.

Paint your window shelf using a paintbrush and the paint color of your choice. For best results, use an oil-based paint and paintbrush. Let the paint dry for two to three hours.

Apply a thin coat of polyurethane with the paintbrush and let it dry according to instructions on the can. Gently sand over the polyurethane with ultra-fine sandpaper, then wipe clean with a tack cloth to finish. Reattach the angle brackets and rehang your newly painted window shelf.