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Aged Dark Brown Finish for Exterior Exposed Copper Sheet Goods

 

I am an Architect specifying copper sheet goods for the exposed copings and flashings on a home in the San Francisco Bay Area. The siding is going to be clear cedar. I would like the copper to weather to a rich dark brown color. I do not want a green patina and I do not want a bight copper penny look. These are the looks the copper finishing products that I have seen are aimed at producing. I would appreciate any advice or leads on how I might obtain the look I seek. Thank you in advance for your assistance.

Ellis A. Schoichet AIA

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For a home-made solution, you could try baking the copper parts in air or in an oxygen enriched environment. For the sake of uniformity, clean the surfaces well immediately prior to treatment, and do not exceed any metallurgical temperature points for the alloy you are using. A convection oven is useful for consistency as is proper spacing to allow for circulation around the parts. If you are using pure copper, 400 °C for a while should be a good starting off point & should make a difference in the color; the timing is dependent on the % of oxygen in the bake atmosphere and the temperature in the oven. Experiment.

The various copper oxides are resistant to water and environmental pollution, but can be removed with acids (e.g., acid rain). Copper is good choice for use with wood. The small amount of copper leached from the trim is usually toxic to algae and moss & can help keep these architectural problems under control.

Dale Woika

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March 4, 2009

I want change color for copper to be brown (as aged brass)
thanks

Joe martinez