Brass is basically an alloy of zinc and copper. Sometimes some other metal may be added to it. Brass items are expensive items and need to be taken care of.
The foremost thing is to make sure that the item is actually made of brass or if it has just a brass polish over it. In the latter case, magnet will stick to it. The brass plated pieces need to be cleaned with a soft cloth or else the thin coating will wear off.
Solid brass items are valuable pieces. On exposure to air, it tarnishes or oxidizes. The removal of tarnish is very important and therefore a clear coating of lacquer is applied on it to prevent the oxidation. Various types of polishes are available such as Brasso etc which are oily in nature; and they do not allow the alloy to come in direct contact with air; thereby preventing oxidation. Almost all the metal polishes contain solvents and detergents (which is required for removing the tarnish), mild abrasive and oils (which is required for inhibiting future tarnishing). Polish should be adequately applied i.e. only in traces as its overuse may discolor the metal.
The entire cleaning and protecting process of the brass includes the following steps :
The general cleaning procedure involves the washing of the brass piece with warm water and mild detergent. For heavily tarnished brass, hot vinegar can be used for its cleaning or even by rubbing half a lemon with salt on it one can do the cleaning very well.
For mild polishing, toothpaste can be used or even a mixture of water, white vinegar and a cup of flour can be used. Remove lacquer coating by applying paint or varnish removing chemical to the brass article. The metal polish is applied in a very little quantity on an absorbent cloth; which is then allowed to dry for some time. Then, along with a grain of brass, it is rubbed on the metal surface. With another piece of dry cloth, buff the brass so that it may shine.
Finally, reapply lacquer on to the brass article so as to provide a protective layer to it. With the help of a paint brush or cotton balls, only a thin layer is applied evenly and is allowed to dry or else finger prints etc will be left behind.
After following these steps, only regular dusting with dry cloth is required to maintain the natural shine of the brass piece.
We must remember that brass can be damaged by excessive cleaning or using abrasives. Brass polishes are also abrasive; so they should not be used very frequently or else the finish will be permanently removed.