Proper Aging for Copper Awnings

Natural Aging

• Copper patina is caused by oxidation, which happens more quickly when the copper is exposed to the elements. The process happens faster in moister climates, but going from new copper to a solid green, Statue of Liberty-type verdigris can take 30 years. Your copper will look new for a month or so, but it will have turned a warm brown by about four months in. The brown will grow deeper for the first couple of years, then hints of green will creep in around the edges. Within five years, the patina will be recognizable but still very brown -- the awning will look streaky and uneven for another five years or so. A 10-year-old awning will look mostly green with hints of a brown undertone, and the green will continue to build up and intensify until the entire awning is a light verdigris.

Assisted Aging

• If you want the light green verdigris right away, some chemical treatments that can speed up the oxidation process. This job is best left to professionals because the chemicals are very caustic and may produce harmful fumes. Patina recipes vary, but cupric nitrate is a popular ingredient, along with ammonium chloride and salt. Some patina recipes require heating with a blowtorch to dry the solution and provide heat for the oxidation reaction. All recipes involve mixing strong acid with water, which can be dangerous unless you're properly trained. Treatments produce a dramatic effect, but multiple treatments might be required to achieve a full patina.

Immediate Aging

• Some awning manufacturers offer pre-aged awnings; these are are either electroplated or painted. The electroplated patinas are more durable than the painted kind and look more like naturally aged copper. A painted patina might be fine for jewelry, but an awning is a big part of the exterior of your house and a big investment, so it's best to avoid paint patinas in this case.

No Aging

• On the other hand, if you fall in love with the warm, rosy glow of brand-new copper, applying a lacquer or acid wash can help protect the copper from the elements so it doesn't age at all. To stay bright and shiny, the copper will need to be polished and buffed occasionally, and lacquer finishes might need periodic reapplication. The acid wash finish is more durable and better for awnings near tree branches or other things that could scratch the copper.