Paint a gel stripper onto the headboard bookcase with a 2-inch paintbrush. Paint only in one direction instead of the usual back and forth motion. Allow the gel stripper to dry and penetrate the bookcase according to the manufacturer's directions.
Scrape away the old paint or finish from the bookcase headboard with a 1 1/2-inch putty knife. Hold the putty knife at 30-degree angle to the wood to avoid marking it. Do not force the putty knife through stuck on paint or finish. Instead, go over the areas with a piece of steel wool.
Dampen a rag with naphtha and wipe the bookcase headboard's surface to neutralize the wood. Wipe lacquer thinner over the bookcase headboard with a rag. Allow the bookcase headboard to dry for 24 hours.
Sand the bookcase headboard's surface with a 220-grit sandpaper. Apply wood putty into holes or cracks using a 1 1/2-inch putty knife. Allow the wood putty to dry according to the manufacturer's directions, and then sand it smooth.
Pour some oil paint into a paint tray. Use a 2-inch paintbrush to cut in and around all of the bookcase's inside edges. Dip a short nap mohair roller into the oil paint. Apply the paint back and forth over the bookcase headboard's entire surface. Allow the oil paint to dry overnight.
Spray a little water onto a small section of the bookcase headboard. Lightly sand the moistened surface with 600-grit wet/dry sandpaper. Moisten another small section and sand it. Continue to work in small sections until you have sanded the entire bookcase headboard. Wait 1 to 2 hours for the surface to dry. Apply a second coat of oil paint the same as the first coat. Allow the second coat to dry overnight.
Give the headboard bookcase a high gloss finish by applying multiple coats of a water-based finish. Allow each coat to dry to the touch before applying the next coat. Use a 2-inch paintbrush and paint roller to apply the finish.