Have you ever wondered just what is the green stuff that gets on coins, pipes, screws, and other metal items? That powdery, sometimes waxy, and admittedly icky green stuff is a kind of corrosion known as bronze disease. Despite its name, bronze disease also tarnishes copper and other copper alloys (bronze is the most famous kind).
Bronze disease is triggered by contamination, such as when an object is drenched in water (especially salt water), coated in dirt, or exposed to air. It’s an irreversible, active process. Once the green appears, the object will continue to corrode.
Damage eventually leads to destruction, but there are ways to stall the effects of bronze disease:
- Remove the moisture damaging an object by placing the affected item inside an oven on low heat.
- Remove the green with a soft brush or toothbrush, then soak it in a solution of sodium carbonate and sodium bicarbonate.
- You can also soak a tarnished item in distilled water – which is the only kind of water you can use to clean and rinse it.
You can also do the following to prevent the onset of bronze disease:
- Keep copper items away from moist or wet places.
- If you have invested or can invest in climate-controlled storage, set humidity to 39% or lower.
- Look into your options for applying a varnish, wax, lacquer, or resin to protect copper items.
Ideally, you should purchase copper items that already come with this form of protection. These coatings provide a barrier between the metal and air, preventing the chemical reaction that triggers bronze disease.