During the Bronze Age thousands of years ago, it was discovered that mixing tin with copper produced an alloy that was stronger than any pure metal. Nowadays, bronze is still commended for its strength but is used as a generic term that lumps together a whole set of copper alloys.
Bronze has always been used in creating items that are designed to stand the test of time - things like statues, medals, musical instruments, weapons, and coins. While it is long-lasting and durable, it is still vulnerable to corrosion.
By understanding how - and why - bronze corrosion occurs, you can take steps to prevent it.
What is Bronze Corrosion - And Why Does it Happen?
Bronze is a combination of elements, generally copper mixed with metals like tin and zinc. Over time, the bronze will begin to oxidize due to exposure to the air and develop a colorful coating. This is often a mixture of colors of red, brown, black, blue, or green.
This colorful outer layer of corrosion is known as a patina coating. And though it may seem like the bronze is ruined, this coating acts as a layer of protection for the bronze, keeping it from deteriorating any further. Some people even find the colors of the patina add more beauty to the bronze.
This corrosion is different from rust. For metals to rust when exposed to moisture, they must contain iron. And, since bronze is iron-free, rust is not a concern.
Bronze Disease
Bronze disease is active corrosion. Items with this condition are constantly corroding - and are in danger of being seriously damaged. To determine between corrosion and bronze disease, look for powder-like growths in shades of green or brown that can easily be peeled off. If you find them, then you know what you’re dealing with.
It takes more than oxidizing with air to spark this disease. It is most commonly found in areas where the air is salty, has constantly high humidity, or contains ammonia pollution. Though not cleaning bronze properly could yield the same result.
How to Clean and Prevent Bronze Corrosion
If you decide that you are not a fan of the colorful patina that has formed over your bronze, then you can remove it. After cleaning the metal thoroughly, you can protect it from future corrosion. Just follow these steps:
Create a Paste and Scrub
Mix baking soda with lemon juice until a paste is formed. Then, after rinsing off your bronze with warm water, use a soft toothbrush and gently scrub the bronze. Once the entire surface area is covered, leave the paste on for approximately 20 minutes or so. Rinse with warm water.
You may repeat this process if needed.
Protection from Future Corrosion
Your nicely cleaned bronze will not be free from future corrosion because it has no protection from the air. Oxidizing will occur without question.
Prevent this from happening by coating the freshly cleaned bronze with a lacquer. Be sure to coat every piece so that you don’t leave it vulnerable and exposed.
Keep in mind that some items that are touched and used frequently may result in the thinning of the lacquer over time. If so, you may see more corrosion. Just repeat these steps to keep your bronze looking fresh.
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