Why does copper make my skin turn green?
My name is Natalie Litchfield. My question is:
When I wear copper jewelry for a day or two at a time ,
I notice that my skin turns green. Why does this happen?
There are several 'green' copper salts which are combinations of
the metal copper and various other chemicals. Examples include
copper sulfate and copper acetate. You will note that the green
color of the Statue of Liberty is the result of the exposure of
copper to the environment which causes oxidation and the production
of green salts. As far as your skin, we constantly release chemicals
from our bodies in the form of sweat. These materials are generally
acidic in nature and will cause metals to 'corrode', or turn, at
least on the surface of the metal, to a salt compound of the metal.
Exactly which of the 'salts' is forming I cannot say. But the
green on your skin near the copper is the direct result.
An interesting sideline.....in olden days, around the time of
Washington, for example, paint pigments were generally not available.
One way people formed their own paint pigments was to suspend
copper metal copper metal in a container over a
pool of acetic acid (vinegar is a solution of acetic acid). The
copper would 'corrode' and the copper salt on the surface of
the copper (copper acetate) could be scraped from the copper
surface, ground up, and could be used as a pigment in paint to
produce a paint color we call verdegris.
Hope this answers your question!
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Update: June 2012