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Weather and Copper Strength
Name: Tim
Status: other
Grade: other
Location: VA
Country: USA
Date: Fall 2009
Question:
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?
Replies:
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.
Regards,
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
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Update: June 2012
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