Cleaning solid brass requires only two common and nontoxic household ingredients: lemon and baking soda. Juice half of a lemon and mix with 1 teaspoon of baking soda in a small bowl to form a paste. The mixture will fizz. When it settles, rub the paste onto tarnished brass with a soft cloth, rinse, and pat dry with a clean towel. Reapply in spots as needed.