Place a magnet on the weight. If the magnet stays attached, the weight is a metal weight with either a brass plating or painted a brass color.
Rub the weight with a fine-grade steel wool in small, gentle strokes to remove the rust spots.
Wipe the weight with a clean, lint-free cloth to remove rust particles and buff the weight.
Place a magnet on the weight. If the magnet falls off the weight rather than staying attached, then the weight is solid brass and the rust is actually simply tarnish.
Clean the weight with a solution of 2 cups of warm water and 2 tablespoons of mild dishwashing soap. Clean the weight thoroughly and soak it for 5 to 10 minutes if necessary to remove grime.
Mix 2 tablespoons of lemon juice and a pinch of salt or baking soda into a paste. Rub the paste on the brass grandfather clock weight with a lint-free cloth to polish the brass.
Rinse the weight in warm water until the paste is completely cleared.
Dry the weight with a clean, lint-free cloth.