Copper roofing, upon exposure to the weather, will begin a process of patination during which it will go from bright and shiny to brown and dull before it develops the characteristic blue-green patina. The length of time required for this to happen varies based upon climate. Copper will patina fastest in climates subject to rain and salt. The length of time for a complete patina may take from three to fifteen years.
Some property owners want their copper roof to stay bright and shiny indefinitely while others want it to develop its characteristic patina immediately after installation.
Coatings are available to help keep the copper bright and shiny. However, the Copper Development Association does not recommend their use on exterior applications due to the difficulty of applying these coatings and the fact that the coatings are not real long-lived. At some point, to keep the copper shiny, it will have to be cleaned and the coating will have to be re-applied. If such coatings are used, they need to be applied to perfectly clean copper. They should also be applied to all surfaces and edges of the copper roofing before it is installed. If the coatings are scratched, they need to be touched up. Coatings are also available to create an immediate bluish-green patina on copper. These coatings should be applied after the roofing is installed. Additionally, several light coats will yield a more consistent appearance than will one or two heavy coats. Information on sources for both types of coatings is available from Classic Products. Also available at extra cost is pre-patinated copper that manufacturers can use in producing their products.