Metal & Copper Roofing Blog

Can You Speed Up the Patina Process on Copper Roofing?

We often get requests for a roof just like like those shown on our website, and particularly for the copper roofs that have aged to a beautiful green or turquoise. People want to know whether it's possible to speed up the patina process on copper roofing, so that their new roof will look older.

Accelerating the Patina

This is different than asking about a fake patina, which would be a painted finish on a different kind of metal. In terms of accelerating the patina process on a copper roof, good news. It is possible.

This is an example of three different samples of patina applications on one of our copper shingle product. These samples were freshly treated and will darken quite a bit with exposure, but the color will remain mostly consistent for some time.

Understanding Patina

The copper patina that accumulates on copper roofing is a natural process resulting over time with exposure to the atmosphere. Copper reacts to rain and moisture in the air, turning the bright, shiny metal into a darker gray/brown and, eventually, to some shade of green. This process happens to every natural copper roof that’s exposed to the weather. Similar to rusting steel, the patina process begins immediately, and will continue indefinitely.

Unlike the oxidation that occurs to steel and iron, however, the patina that forms on copper provides a not insignificant amount of protection to the base metal. The patina actually protects the metal from corrosion, in addition to being aesthetically striking.

The patina develops through stages of color, and the greens and blues are reached after many years of exposure. When the environment is warmer and more humid, these colors are reached more quickly. For copper roof owners in dry, cold, or desert climates, exposed copper can take generations to oxidize to a visibly green patina.


Patina Shortcuts

Explaining the patina process is one thing - accelerating it is another. There are old records of horse urine being poured on new copper roofs in an attempt to make them appear old and green. Fortunately, today's methods are more effective (and less disgusting).

Most methods involve some kind of acid with chemical additives to accentuate the green, blue, gray or black patina of copper. When we're asked here at Metal Roof Network to provide pre-aged copper finishes on our copper roofing, we use proven formulas that we know to be predictable and safe. It's the application itself that has the biggest impact on the finished roof. Even with the same chemical, the result will be affected by variations in:

  • temperature
  • humidity
  • application technique
  • angle and exposure of surface
  • drying time

If any of these conditions change from one application to the next, the final result will be noticeably different.

It's important to understand that accelerating the patina isn't like adding a coat of paint. There is no way to achieve a consistent, even shade of one type of patina green. That's what makes it so beautiful! Plus, after installing and exposure, the pre-patina application will continue to change and develop over time. Usually, it becomes deeper and darker, with areas of greater intensity wherever moisture may accumulate.

For more information about our copper roofing and patina acceleration, contact us today.

Topics: copper roof supplies, copper roofs CA