In the past I installed copper roofs flashing and gutters. I have been asked more than once by customers "Is there a way to make the copper turn green faster?" When I was first asked this question I thought "There are people that actually like the look of oxidized copper?" Apparently people do like that antique green and surprisingly want the process to happen faster than nature would intend. I have never tried to make copper turn green but that doesn't mean I wont do it in the future. How does one do this?
That natural green coating is called Patina and it is caused by oxidation of the copper over a period of time. That oxidation can be sped up by treating the metal with some form of acidic solution.
You can make your own acid mix at home. You must wear rubber gloves when handling these chemicals.
Personally I don't like the green affects from an acid treatment but who knows? I may decide to add a patina service to my bag of tricks.