Copper used in buildings

[marmaduke]

How long does the copper used in domes and architectural flourishes take to go green? Did they originally know it would, and allow for it? I've never seen a building with copper that isn't green, so it must have looked quite interesting when still metallic and shiny.

[Clanad]

Verdigris, the beautiful patina that naturally protects copper, develops at differing rates and is dependent on a number of factors. Eight to ten years appears to be an average. As stated, the development of the patina actually protects the copper from further corrosion.  Some manufacturers apply coatings to delay the onset of the corrosion, but they haven't been all that successful.  Since copper has been used for centuries, the builders that use this material have known that it normally corrodes for an equally long time... Check here for further information...

http://w3.gsa.gov/web/p/hptp.nsf/0/f0c205eec8a1107a852565c50054b3f8?OpenDocument

[marmaduke]

So it's very much a case of, enjoy it while it lasts, which isn't too long? On the Oxford Bodleian Library angels are shown blowing trumpets made of copper, which must have looked dazzling in the 17th century, but now look like green toy blowers.