Brass, like most other metals, tends to tarnish over time. Tarnish doesn't actually damage the metal, but it is somewhat unattractive, especially on decorative items such as jewelry, light fixtures and nautical detailing. One way to protect your brass and keep it looking new is to apply a coat of protective lacquer.
Examine Your Item
Plated brass is more delicate than solid brass, so before you clean or lacquer your item you need to figure out which it is. Magnets will not stick to brass, so try that first. If the magnet sticks, your metal is not brass and you might have to do a bit of investigating to figure out what it is. Or you may have brass plating over a ferrous metal. You can also scratch the surface of your item in an area that will not show. If the interior of the scratch is yellow, you have solid brass. If a magnet does not stick and your scratch is any other color, you have plated brass over nonferrous metal. Brass plating is usually somewhat thin, so cleaning it will require a gentle hand. If you are working with valuable antiques or heirloom jewelry, you might consider taking them to a professional to be re-lacquered.
Clean Your Brass
Wipe away any dust and dirt with a clean, lint-free cloth or soft-bristled brush. Remove any existing lacquer with a solvent designed to emulsify the protective coating. This can be found at any paint, home improvement or hardware store. Paint thinner, banana oil or acetone, which is commonly found in nail polish remover, will also work. Removing the old lacquer is necessary to ensure that the new coat goes on smoothly and adheres well. Either dip the item in the solvent or apply it with a clean, lint-free cloth. Let it sit until the lacquer begins to bubble, and then wipe the piece clean. Use a small brush to scrub away any stubborn bits. Do not use a brush with metal bristles because you can scratch the brass. This is especially important if you have plated brass, because scratching it will allow the metal beneath the plating to show through. Always work in a well-ventilated area and use protective breathing gear when working with lacquer solvent.
If you prefer to avoid using solvents, soak your brass in a solution of 1 cup baking soda to 2 gallons boiling water. Let the item soak until the water is cool. Remove the object from the water and peel away the lacquer. Use a brush with non-metal bristles to help loosen the lacquer if you need to. This method requires some time and effort.
Apply the Lacquer
Brass lacquer can be applied by spraying or brushing it on. For brass pieces that are not attached to anything else, lay down a dropcloth. To protect the area around brass fittings such as doorknobs or lighting, use painter's tape.
Wear protective goggles and breathing gear if you are using a spray lacquer. Apply the lacquer in a thin, even coat, paying special attention to small nooks and crannies in more ornate pieces so that the lacquer covers them completely but does not pool or drip. Let the brass lacquer dry completely according to the manufacturer's recommendations.
If you are not using an aerosol lacquer, you can either brush it onto your items or dip them and hang them up in a well-ventilated but protected area and let them dry.
Sand the dry lacquer gently with very fine sandpaper of 400-grit or finer for a mirror-smooth finish. Wipe away the sanding dust with a clean, lint-free cloth and apply a second coat of brass lacquer. Let it dry for the recommended time.
Care and Maintenance
Keep your lacquered brass free of tarnish and wear by cleaning it regularly. Wipe the brass polish with a clean cloth, buffing it until it shines.