Patina: The Natural Evolution of Copper Roofing

Copper is a popular choice for quality roofing, gutters, and downspouts, as well as roofing fixtures and decorative elements on walls, entryways and basically anywhere it adds a design element. This beautiful metal is both lightweight and malleable, making it an excellent choice for custom residential and commercial projects. A copper roof can last up to 100 years, which makes it far more durable than most other roofing choices.

One intriguing quality of copper is its changing color over time. This color evolution is less well understood, but is an important factor in the durable beauty of this amazing decorative building and roofing material.

Copper Roofing: The Beauty of Copper Patina

While copper gutters and downspouts, as well as roofing, start their service with that beautiful golden-bronze color, the “new penny” copper shine, eventually they will develop a patina that changes over time.  The time frame and shades of color each building goes through vary, but eventually the copper will end up a brilliant green. Rather than thinking of this as a defect, homeowners should appreciate this as part of the natural maturing process of copper.

The process occurs like this: As the metal is exposed to the air, it begins to oxidize and a thin layer of corrosion forms. This layer, known as a patina, is incredibly thin. As the years pass and the roof ages, the patina will thicken and change colors. Colors often include shades of copper, green, dark brown, and turquoise.  Eventually, the roof will even out to a brilliant green.

The exterior of the Statue of Liberty is made of copper, about the thickness of two pennies. Its beautiful, mature green patina gives the statue a graceful glow that seems to bring her to life as she stands over Liberty Island and the New York Harbor. This is a mature copper patina at its finest.

How Long Does a Patina Take to Form on Copper Roofing?

While a patina is inevitable, the length of time it takes to form is dependent on several factors:

• The initial cleanliness of the copper can slow oxidation.  For example, if the manufacturer uses lubricants in the manufacturing process, then a thin film may remain on the roofing material, slowing down oxidation.
• Local environmental conditions can speed or slow the rate in which the patina forms. A patina requires moisture and air contaminants to form.  Copper that is in a perfectly clean and dry environment will not oxidize and form a patina.  Patinas will form more quickly in an environment that is rich in moisture and contaminants such as sulfur, chloride, etc., such as from pollution, volcanoes, and other sources. A patina can take significantly longer to form in a very dry climate like Las Vegas, but will form faster in a coastal environment like Southern California.

• A patina commonly has an uneven appearance.  A patina is a natural process, and therefore, will not happen at a uniform rate. Copper roofing, even if it is installed at the same time as gutters and downspouts, will not age at the same rate. Sun exposure, the angle of installation, and the amount of moisture from the morning dew can all cause differences in patina on a single roof.
• Achieving a quality patina in our desert climate. Copper roofing and gutters are slow to patina here in the desert with our dry, hot climate. It may take many years for the green patina to occur. Washing the copper with different solutions can accelerate the natural patina process. For instance, a simple salt water bath will start the natural tarnishing to start. Acid washing the copper will make the green patina happen. Other factors like temperature or humidity will affect the process so care should be taken to control when and where the wash is applied.
• Allow the natural process to happen. Cleaning the copper to restore its original appearance is possible, although the tarnish or patina will come back. Attempting to halt the natural patina process and keeping the shiny appearance of new copper by sealing the materials is never recommended because any sealer used will have to be reapplied and maintained. You could unintentionally end up with an uneven patina that diminishes the beauty of the roof.

Once you understand that a patina is part of the natural lifespan of a copper roof, you can fully embrace its natural beauty and look forward to the changes in appearance you will notice as each season passes.

If you are ready to explore the possibilities of copper, contact us, call 702-646-7536, or visit the Prestige Roofing showroom at 3405 Bunkerhill Drive in North Las Vegas.  We offer free estimates on residential and commercial roofing and roof repairs.