Tips: Fine Metals
Silver
Most silver bought today is sterling silver, which means the object is 92.5% pure silver and 7.5% copper alloy. Most common types of silver objects are flatware, jewelry, and small decorative items such as candlesticks. Silver will tarnish naturally but air pollutants and high relative humidity will speed it up. The worst air pollutants for silver are sulphur based, and can be found in velvet and felt, which are often used as linings for jewelry and flatware cases. It is best to remove these linings if possible. If not, place plastic wrap or polyethylene bags between the objects and the lining to act as a barrier layer.
It is best not to polish silver items as the tarnish acts as protective layer between the underlying metal and the environment. Each time you polish, you remove a layer of the silver, and if the object is electroplated, you can eventually remove all the silver. Silver will also scratch very easily and that is why few commercial polishes are recommended - they are too abrasive. If you must polish the silver, Twinkle, Goddard's products, or Hagerty's products are best. Also if possible, place the polished pieces in polyethylene bags. The bags act as protection against the environment, and the pieces will tarnish much slower when placed in the bags. Silver jewelry should be polished with a jeweller's cloth and stored individually so that they cannot abrade each other.
Handling: Always wear clean cotton gloves when handling silver. The acid in your skin will etch into the metal in less than one month, creating permanent damage. Latex or rubber gloves will react with the silver and cause increased tarnishing. Always support the object with two hands, and do not carry more than one object at a time.
Storage: The recommendations are the same for glass and ceramics. If placing silver in boxes, place in polyethylene bags first and then wrap with white, terry cloth towelling.
Copper, Brass and Bronze
Brass is a copper and zinc alloy. Bronze is a copper and tin alloy. You cannot really tell the three apart by appearance, scientific analysis is needed to be positive. Copper will corrode faster than either brass or bronze. Corrosion often appears as bright blue or green areas on the object. Do not try to remove these yourself - contact a professional conservator. If possible, do not polish copper as the tarnish acts as a protective layer between the underlying metal and the environment. Also, copper is often attached to leather harnesses or other materials. The residue from the polish will damage any leather or textile with which it comes into contact. If you must polish, Twinkle, Goddard's products and Hagerty's products are best. Do not use silver or other types of metal polish on copper.
Copper, brass, and bronze are not as susceptible to air pollutants as silver.
Handling: Always wear clean gloves - cotton or latex are fine in this case. Always support the object with two hands, and do not carry more than one item at a time.
Storage: If placing copper, brass or bronze in boxes, place in polyethylene bags first and then wrap with white, terry cloth towel.
Gold
Gold will not corrode but if it has a silver or copper alloy with it, those metals will.
Do not use any polishes except for a jeweller's cloth on gold as it is very soft and can be easily scratched and misshapen.
Handling: Wear clean gloves - either cotton or latex. Follow same procedures as for copper, brass, and bronze.
Storage: Same guidelines as for copper, brass, and bronze.
