Why do copper bracelets leave a residue on the skin?
As an element found naturally in the earth, copper requires refining into the metal worn as jewellery. Copper’s ability to conduct electricity with minimal loss of energy makes the metal extremely valuable. When exposed to other chemicals or outside elements, even those as simple as oxygen, copper reacts, leading to changes on its surface.
Copper reacts with the oxygen and moisture in a reaction called oxidisation, it’s perfectly harmless and is just nature’s way of depositing the minerals onto your skin, how fast this happens depends on the ph balance of your skin and doesn’t affect the way the bracelet works.
The acidic nature of human sweat and other chemicals on the skin, such as soaps, lotions and makeup, react with the copper. This reaction causes a green patina or surface coating to form on the copper, and that colour gets transferred onto the skin. The reaction varies according to individual body chemistry, both in how long it takes for the green discoloration to form and in how distinct the colour becomes. Some people might not experience any discoloration at all.