Sterling silver is an alloy composed of 92.5 percent silver and 7.5 percent copper. Sterling objects are marked with the number 925, the fraction 925/1000 or the word sterling. They may also bear the maker's name or trademarks. Sterling silver utensils and decorative objects show an attractive color and luster when clean, but they are prone to tarnish that initially has a copper hue and later turns black.
Tarnish & Corrosion
Sterling silver tarnishes when the metal reacts with sulfur compounds in the air and with the salts, oils and acids from your skin. Sterling silver stored in an unclean condition in a damp place may develop crusty green deposits from corrosion of the copper in the silver alloy. The best way to preserve your sterling silver is to prevent tarnish and corrosion.
Clean Your Sterling
After using your sterling, wash it by hand with a non-lemon-scented, phosphate-free dish detergent. Dry your sterling items immediately with a soft dish towel. You should never wash your sterling in a dishwasher. The high heat and harsh detergents may leave a hard-to-clean white deposit on the silver, and may loosen knife handles and any non-metal components of the silver pieces. Salt and pepper corrode silver, so shakers should be emptied and all parts washed and dried before storage.
Store your sterling silver in a chest, closed display case or polyethylene bags. Store it with commercial anti-tarnish strips and silica gel moisture absorber. For added protection, you can wrap your sterling silver in a commercial silver-impregnated anti-tarnish cloth before putting it in storage. Avoid cardboard boxes, newspaper, plastic food wrap or rubber bands for storing silver. These contain acids and other chemicals that aggressively attack silver.
Despite the best of care, your sterling silver eventually will become tarnished. Light tarnish can be removed with a commercial silver cleaner. Heavier tarnish may need a commercial silver polish or silver dip. Use according to product directions. Once clean, you can polish your sterling with a moist soft cloth or sponge dipped in the silver polish. Work in a straight line, not a circular motion. Use cotton swabs in crevices. Avoid using toothpaste or baking soda as a silver polish. They are too abrasive and can ruin the finish. After polishing, rinse your sterling in warm water and dry thoroughly. To bring out the shine, buff your sterling pieces with a commercial silver polishing cloth.