Brass is an alloy of copper and zinc. There are three general varieties of brass: plated, solid, and lacquered.
Brass-plated items are usually not brass at all, but are rather made of steel with a thin plating of brass on the outside.
Solid brass is what many consider to be "true" brass, as items of solid brass have no coatings or additional metals in their makeup. Solid brass is also the best candidate for a traditional polishing, whereas the other two types require more sensitive approaches.
Almost all brass tends to oxidize (tarnish) quickly when exposed to air, which is a major reason why some brass is given a clear coating of lacquer to prevent this condition. When a brass piece receives this protective layer, it is called lacquered brass.
Restoring Plated Brass
The biggest distinction to keep in mind when working with dingy or damaged plated brass is that it doesn't actually tarnish - it rusts due to the steel base. As counterintuitive as it may seem, the worst possible way to go about cleaning brass plating is to use a conventional polish like Brass. Don't polish plated brass. The only thing a polish will remove with this variety is the brass itself.
The best way to address rusts or blemishes in this case is to wipe at the affected areas with a homemade recipe for cleaning brass . You can also use water and a soft cloth. Be gentle, as plated brass scratches easily. If simple soap and water doesn't do the trick, you can try something slightly stronger like dish soap. Unfortunately, this is the last step you can take on your own. If any brass imperfections remain after working up to the dish soap, the most feasible option to save the item is to take it to a professional and have it re-plated with new brass.
Polishing Solid Brass
Solid brass can stand up to tougher restoration techniques and will benefit from a good polish. All you need to do is give the solid brass a simple wash with soapy water, let it dry, and apply the polish. Most conventional polishes such as Brass or Twinkle will coat the raw metal with a thin film of oil to help inhibit future tarnishing. Additionally, most metal polishes contain solvents and detergents to remove the tarnish, mild abrasives to polish the metal, and oils to act as a barrier between the raw metal and air.
Only a trace amount should be applied, creating a thin film. To do this, an adequate amount of metal polish should be applied and spread out on an absorbent rag. Let the rag dry out for a minimum of 24 hours before applying. Apply this trace amount of polish with the grain of the brass with one hand while buffing it out in a rapid motion (creating friction) with the other hand. This burnishing action will harden the polish, like "spit shining" a shoe, and create a surface far more difficult to smudge or discolor.
Assuming that you have polished raw or solid brass properly, you may want to lacquer it at this point as an added method of protection. Or if you don't want to use lacquer, olive oil is a good compromise. Brass will look brighter and require less polishing if rubbed with a cloth moistened with olive oil after each polishing. The oil naturally retards tarnish.
Don't overdo it with the polish. Many people overuse and flood metal surfaces with polishes believing that they are better protecting the surface. The more polish, the more protection, right? Wrong. Very wrong. It's important to use the proper procedure when restoring your metal.
More polish creates a smudging problem since fingerprints and the trace human body oils that are transferred anytime you handle an item "dissolve" the solvency of the metal polish. Additionally, too much polish may discolor the surface. Brass can sometimes turn "black" when cleaning due to overuse or misuse of polish.
Treating Lacquered Brass
As already stated, lacquered brass has an entire layer of coating with the singular purpose of preventing the actual brass from being exposed to the elements and abrasive chemicals. This includes brass polish. Attempting to polish brass with the lacquer still applied won't clean anything. The lacquer and polish will work against each other and give the item an ugly, cloudy look.
Remove the lacquer first with some acetone or nail polish remover. At this point, your formerly lacquered piece is just an ordinary piece of raw brass as explained above, so you can treat it identically and polish carefully. Then reapply new lacquer.
Lacquering can be done at home, but all old lacquer must be removed and the surface completely cleaned (no fingerprints or cleaner on it) before spraying the lacquer on evenly in multiple thin coats.
Keep lacquered items dusted and clean. Follow our easy guide on how to clean lacquered brass. Never use hot water on lacquered items, as it loosens the lacquer. Do not polish them or soak them in water.
Caring for Antique Brass
To polish antique brass pieces, you must first wash them in hot, soapy water to remove grime, wax, etc. Rinse and dry.Then moisten a soft cloth with boiled linseed oil and rub it on the brass surface until all the dirt and grease have been removed. Then polish using the aforementioned method.
To remove heavy tarnish, difficult stains, and corrosion: wash in hot, soapy water or a weak ammonia and water solution, and then rinse and let dry. Dampen a soft cloth in hot vinegar, then dip in table salt and rub the brass, or make a paste of flour, salt, and vinegar. You may need several applications. When the item is clean, wash in hot, soapy water, rinse, and dry thoroughly, then polish with a cloth moistened with lemon oil. If preferred, dip a slice of fresh lemon into the table salt mixture and rub over the corroded area. Wash, rinse, and dry carefully.
Antique brass items, especially ones in poor condition, require special care. Consult museum experts for advice.
Tending to Brass Hearth and Fire
Brass hearth and fire sets that have been neglected require special treatment. They can even be rubbed with extra-fine steel wool. However this requires much time and work. Fine emery cloths will give quicker results, but the metal must be rubbed in only one direction, not a circular motion. When clean, polish with a brass polish. Some commercial polishes do not require rinsing, so follow label directions.
Remember, this is the one exception where steel wool is an option. Most other brass scratches easily so the most abrasive cloth you should be using there is a light duty sponge or a fine dust cloth.