Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Weather and Copper Strength
Name: Tim
Status: other
Grade: other
Location: VA
Country: USA
Date: Fall 2009

If copper is left outside in the weather before it is installed, can the weather affect the strength of the copper? I realize that it can make the copper change color, is this also am indicator of possible future corrosion?

Hi Tim,

When copper is left out in the elements, it develops a very thin, complex layer of (often brightly colored) copper oxides, copper carbonates and copper sulfate, on its surface. These protect the underlying metal from further corrosion. This surface corrosion layer is responsible for the color you are seeing, not changes in the underlying copper itself. The strength of the copper that lies under this surface layer is utterly unaffected because the extremely thin surface corrosion layer protects the base metal. The color you see is not an indicator of future corrosion; it simply indicates the presence of a thin layer of surface corrosion that acts very effectively to prevent the bulk of the copper below from destructive corrosion and damage.

Bob Wilson

The green color (called patina) is a surface corrosion, but it does not greatly affect the structural strength of the copper.

Vince Calder

Click here to return to the Material Science Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory