What if the traditional rubber band of copper bullets loves black?

You can soak and wipe it with some soap and vinegar.

It is a common phenomenon that copper turns black mainly because it is oxidized in the air. You can use some vinegar bubbles to dissipate.

What if bronze is black? Soap or mild detergent: If brass ornaments are dusty or dirty instead of darkening, soak them in warm soapy water and clean them with a soft cloth. Especially dirty places can be gently brushed with a toothbrush. You can also use vinegar, salt and flour: these multipurpose kitchen utensils can be used to make paste to clean darkened brass ornaments. Dissolve a teaspoon of salt in half a cup of vinegar and add flour until it becomes paste. Rub on brass, rinse with warm water after 10 minutes, and dry.