Prepare a solution of lemon juice and either salt or baking soda. Both make a lightly gritty solution that removes dirt and caked-on debris from soldered brass. Combine the juice from half a lemon with a teaspoon of baking soda or salt, using a small bowl to hold the cleaning paste.
Apply the paste to the brass, using a soft cloth. Rub in one direction using gentle, even pressure. Work the paste into tight corners, using a cotton swab.
Rinse off the paste with a rag dipped in water. While one cleansing works well to maintain soldered brass, soiled pieces need more care. Repeat the cleaning process on dirty areas until the entire piece looks clean, making more lemon juice paste as necessary.
Buff the brass with a dry cloth until it shines.