Attach the sandpaper to an orbital sander and sand the lamp in steps, beginning with 60-grit sandpaper and finishing with 120-grit sandpaper. If you must hand sand, sand with the grain rather than against.
Apply oil-based primer to the lamp using a fine-bristled brush. Paint on three coats, allowing 30 minutes drying time between coats. Lightly sand between coats to smooth out brush marks.
Apply three coats of base coat milk paint. Mix the milk paint in a small container, following mixing instructions on the bag. Allow the milk paint to set for 30 minutes between coats and sand lightly with 120-grit sandpaper to remove brush marks.
Apply the top coat of milk paint in one coat. Allow the top coat to set for 30 minutes and gently wipe away in spots with a damp cotton rag to simulate paint wear. For example, wipe away a small amount of paint near the corners and at the top of the base where a hand might touch when turning the power on and off.
Allow the top coat to set for one hour. Apply three coats of satin clear coat. Gently brush the coats on with a fine-bristled brush, allowing 15 minutes drying time between coats.