Copper bracelets are popular for their looks and alleged healing properties. But after you wear one for a while, you might notice that the skin underneath the copper turns green. This is a normal reaction that occurs with any kind of prolonged copper exposure on the skin. The green colour will fade if you stop wearing the copper, and it is not harmful to your health.
Copper is an element found naturally in the earth, but it must be refined into the metal that we are familiar with from copper jewellery, kitchenware and wiring. It is highly valued for its ability to conduct electricity with minimal loss of energy. When exposed to other chemicals or outside elements, even those as simple as oxygen, copper can react with them, leading to changes on its surface.
The most commonly seen chemical reaction in copper is oxidation. This occurs when copper is exposed to air, and it results in the copper's surface darkening. When that surface is also exposed to saltwater, the copper can turn bluish-green. This is similar to its reaction to prolonged contact with your skin.
The acidic nature of human sweat and other chemicals on the skin, such as soaps, lotions and make-up, react with the copper. This reaction causes a green patina (surface coating) to form on the copper, and that colour is transferred onto skin. The reaction varies according to individual body chemistry, both in how long it takes for the green discolouration to form and in how distinct the colour becomes. Some people might not experience any discolouration.
Although skin acidity might seem like a drawback when dealing with jewellery, research by the San Francisco Veteran's Affairs Medical Center shows that the acidic nature of skin plays a part in holding the skin surface together, as well as strengthening it and protecting your body from disease.
Copper bracelets can be copper all the way through, or they might be formed from another, usually less expensive, metal and simply have a copper layer on the outside, known as plating. Both types of bracelet can cause the same reaction, but copper-plated bracelets might eventually wear through the copper plating on the inside--particularly if you clean them frequently--leaving the underlying metal, rather than the copper, exposed to your skin. This might eliminate the skin discolouration unless the underlying metal also is oxidation-prone, such as nickel.
Many copper bracelets are sold with purported healing properties from the direct contact of copper with skin. However, if you are wearing the bracelet purely for adornment, you can try sealing the copper to prevent skin discolouration. The most common method for doing this is by applying clear nail polish to the inner surface of the copper. This creates a barrier between the acids in your skin and the copper surface. However, the treatment must be repeated periodically, and it might not work if you have highly acidic skin or use acidic skin products.
For a slightly stronger, longer-lasting barrier, apply car wax to the inside of the bracelet, and buff it off per the package's instructions.