The metals that occur in ecclesiastical objects are usually silver, gilded silver, pewter, and alloys such as brass and nickel silver. Iron also occurs in some objects. The gilding is often carried out using an old technique known as fire-gilding. Metal objects are damaged by air pollution, moisture, and changes in temperature. Ecclesiastical objects are also exposed to other harmful substances. Corrosion is caused by candlewax that is not removed, leftover wine in jugs and chalices, water that is not wiped off vases, font inserts, etc. Remains of polish can eat holes in metal. Mechanical damage can also occur with careless handling. When cleaning vessels care should be taken not to support the base or the edge on a hard surface as this can easily cause distortion or bending. To avoid distortion of the arms of chandeliers or candlesticks, a supporting hand should be held under the candle socket when the candle is inserted. The candle should be shaped at the base in such a way that it is easy to insert in the candle holder. Sharp tools must not be used for removing candlewax, which should be rinsed away with hot water. Wooden tools may be used if necessary. Polishing silver, brass, and pewter is also discussed.