The Appearance of Copper Alloys

Since copper and copper alloys can take on a variety of wonderful colors and shades, they are widely used in architectural applications.  Either naturally over time or through chemical processing, copper alloys can be brown (statuary finish), blue-green (patina finish), rose,  red, or simultaneous combinations of any of these colors.

In general, the environment to which a piece of copper or copper alloy is exposed and the time of exposure dictates the appearance it takes.  Humidity levels, the existence of certain chemicals or minerals in the air, surface preparation, and time can all play a part in how this beautiful and mysterious material will look.

Statuary finish, like an old copper penny, is sometimes referred to as antique copper.  It can range in color from a light brown to nearly black and sometimes has highlights of copper color showing through.  This brown color naturally develops over time as a result of surface oxidation, but it can also be created artificially with the use of chemicals - usually solutions of polysulfide - or through electrolytic oxidation.

The sought-after natural blue-green patina color can take many years to develop naturally.  In fact, in some environments it may never develop.  The color is created as a film of copper sulfate develops on the surface.  This film typically develops in chemically "dirtier" environments, such as coastal or urban areas.  Patination can be artificially created by applying certain sulfates or chlorides under controlled conditions.

The Peninsula Mailbox and certain copper components of other mailbox products will change color as they mature over time.  Their appearance is difficult to predict since it is dependent upon the environment, but they will likely turn a darker antique copper color before developing areas of a patina color.