Things You'll Need
Instead of updating the look of brass doorknobs with replacement doorknobs, you can use spray paint to alter the color for a fresh look. Preparing the surface of the doorknobs properly ensures that the paint adheres well and looks professional. The tools you need to paint brass doorknobs are available at home improvement or paint stores. Be sure to select a spray paint and primer developed specifically for painting metal surfaces.
Unscrew the screws that attach the doorknob to the door. You can paint the screws to match or use new screws.
Prepare the surface of the brass by sanding the entire area lightly using a fine-grit sandpaper. Sanding the surface makes the metal rough so that the primer and paint adhere well. Wipe away any dust you have created with a clean, dry cloth.
Poke the screws, the neck of the doorknob and any other parts into a piece of strong cardboard. Push the screws through so only the screw heads are exposed above the cardboard; push the doorknob into the cardboard just enough that the top of the part is steady. The cardboard will keep the pieces upright so that you can easily paint all exposed sides of the parts at once.
Apply the spray primer to the metal. Follow the manufacturer's directions for use. Shake the can to mix the primer, then remove the lid and spray every surface of the metal in smooth, even lines. Spray at a distance of 12 inches from the parts.
Allow the primed doorknob parts to fully dry.
Paint over the primer using spray paint. Follow manufacturer directions. Shake the can, remove the lid and spray from 12 inches away. Use long, even strokes to cover all of the doorknob parts in an even coat.
Wait until the paint has fully dried.
Remove the parts from the cardboard and reassemble the doorknob on the door.
Work in a well-ventilated area when sanding, priming and painting to avoid overexposure to dust and fumes. Protect yourself by wearing a mask or respirator.