Over time, even the shiniest brass gets tarnished, dirty and dingy. In many cases, simple household products such as vinegar and salt can clean brass. They're a safe and inexpensive alternative to commercial cleaners.
Lacquered vs. Non-Lacquered Brass
Some brass objects have lacquer, or a coating with a clear sealer, to help prevent discoloration caused by oxidation. If the brass is new, looks extra shiny, is easy to scratch with a fingernail or has areas that look like something clear chipped away, it's probably lacquered. Don't apply vinegar and salt to lacquered pieces, as this combination could damage the lacquer. Instead, clean the brass with a damp cloth, using as little water as possible. Dry the piece afterwards.
Solid vs. Plated Brass
Some objects that look like brass are actually another form of metal with a thin layer of brass plating on top. To determine whether the piece is true brass or brass plated, test it with a fairly strong magnet. A magnet won't stick to solid brass, but it will stick to some metals that may be underneath a layer of brass. A magnet isn't completely foolproof. It will only stick if the plated object is magnetic. If the magnet doesn't stick, and you still aren't sure, look for chips or wear in the brass. If you see another metal color showing through, the object is plated rather than solid brass.
Clean plated brass by wiping it with a damp cloth. If necessary, use a small amount of salt on the cloth as an abrasive. Wipe the piece clean with a damp cloth, then dry the object.
DIY Polishing Paste
Make your own brass-cleaning paste by mixing equal parts salt, flour and white vinegar in a shallow bowl. Cover the brass object with the paste, working it into any grooves or details. After 10 to 15 minutes, scrub the piece with an old damp toothbrush or a rag. Wipe the brass clean with a damp rag, then buff dry with a soft cloth such as flannel. If cleaning up an electrical item such as a brass lamp base, unplug the lamp first.
Remove tarnish from a relatively small, solid-brass object such as a bookend or souvenir by soaking it in a mixture of one part white vinegar, two parts water. Submerge the piece for several hours, then wipe it with a water-dampened white cloth. Buff the brass dry with another soft white cloth. Don't soak objects that have felt pads on the bottom or that contain other non-brass elements, as the liquid could damage those areas.
Salt and lemon juice clean solid brass pieces in much the same way as salt and vinegar. Sprinkle table salt on the cut side of a lemon half, then rub it over the tarnished object. This also works with a previously juiced lemon half, since a little of the lemon's acidic juices remain. Buff the piece with a dry soft cloth, then wipe it again with a damp rag and another dry cloth.