Why Does Copper Oxidize

Humanity has been acquainted with the use of copper for thousands of years. Copper is a multipurpose metal having a range of applications, such as in cookware, jewelery, electrical wiring etc. Sometimes you encounter a copper covered with lacquer, yet remained as such in pristine condition. But there are coppers that turn green over time.

Process of oxidation explained:

Metals on exposure to oxygen change color. The chemistry behind is that oxidation occurs when a metal loses one or more electrons, resulting in corrosion. With the result of prolonged oxidation, a metal is reduced to rust.

Oxidized Copper Egyptian Coil Bracelet Why Does Copper Oxidize

How does copper oxidize?

In the presence of oxygen copper starts giving in to the process of oxidation. After some time it forms copper oxide, dark brown in color.

The next step of copper oxidation requires a relatively damp atmosphere and the result is copper carbonate, green in color. This copper carbonate is called “patina”. It is the thin film of patina that prevents copper from further corrosion.

Different people react to patina differently. Some like the green color stay there, esp. when compared with antique copper. Others may wish their copper to be glittering bright.

The Statue of Liberty is a very famous example of oxidation. The copper used in it has a green colored protective film, about 0.005” in thickness. This natural protective film called ‘patina’ protects the statue from any further oxidation by being exposed to air and water.

How to Clean Copper

Sometimes your copper is coated with lacquer within factory; it will stay in its original condition so long as the lacquer lasts. You can just dust your piece or you may even wash it in moderate soapy warm water and rinse later.

You can also purchase a copper polish at your local store. Apply polish as per instructions contained therein and there you find your copper stuff back to its original appearance.

To ensure more shining you may sprinkle the lemon with baking soda and rub over copper. Then rinse your copper stuff with water and wait till dry.

Heat Transfer in copper:

Heat can easily be transferred even after the formation of patina. The principle operating behind this process is the same as in a convection oven. The copper so oxidized is still malleable despite the presence of the layer of patina on the surface. As the film of patina is very thin, it doesn’t affect copper’s ability to radiate heat any significantly. There may be some varying results of heat transfer depending upon the method of transfer used.

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