How to Clean Rust Spots From Bronze
Bronze does not really rust. "Rust" is an appropriate term for iron-based metal objects only, as John Christie explains on the Mad Science Network. Rust appears as a result of the interaction of air with the chemical properties of iron. "On copper, bronze, or silver, we talk about a 'tarnish' if we are thinking about the degradation of the metal surface, or a 'patina' if we are thinking about the pretty and sometimes artistic effects" of this same process, Christie notes. Bronze, an alloy of copper and tin, normally reacts very slowly and produces a tarnish that eventually turns green. It is fairly easy to clean and prevent.
Remove any existing lacquer finish on the bronze item you are cleaning. Lacquer is often applied to decorative bronze items as it provides a clear, protective finish. Open the windows and turn on fans in your work area to provide ventilation before beginning -- chemical lacquer removers produce strong fumes.
Pour enough acetone into a bucket, sink or any container large enough to hold your item (if not possible, then apply with a clean cloth). Use a toothbrush or other soft-bristled brush to scrub gently -- harsh scrubbing or scrubbing items may damage the bronze. Rinse thoroughly when complete.
Mix acetic acid (vinegar) with baking soda. Allow the solution to bubble, then blend into a thick paste. Exact amounts are unimportant.
Apply a small amount of paste with your finger to your bronze item, using gloves to protect your hands. Rub it in using a clean cloth or toothbrush and working in either a circular motion or with the natural design to avoid scratching (remember bronze is a soft metal). Continue applying across the entire item.
Allow the paste to set on the item for a minimum of 30 minutes. Work the paste into the bronze again before rinsing with clean, warm water. Buff the bronze with a soft, dry, clean cloth to achieve a new shine.
Cover your bronze with a light coating of hot wax, heating it in a double boiler until liquid. Dilute the wax with a small amount of mineral spirits or lacquer thinner to create better adhesion (perhaps 1 tsp. to every 1 cup of wax). Brush on with a shoe polish brush or clean cloth, applying liberally. Allow the solvent, if present, to evaporate. Buff with a fresh cloth or clean brush to finish. This coating replaces the lacquer and prevents future oxidation, but should be periodically reapplied.
Things You Will Need
- Acetone (or nail polish remover)
- Toothbrush or soft-bristled brush
- Acetic acid (vinegar)
- Baking soda
- Rubber gloves
- Soft cloths
- Hot wax
- Mineral spirits or lacquer thinner
- Various cleaning and polishing agents exist that will work with bronze. Commercial cleaners and even immersion in a mixture of vinegar and salt (which can be heated) will work.
- For expensive items, it may be useful to consult a professional before attempting any cleanup or repair of bronze items.