I can't answer that, but I can tell you I was royally chewed out by a client for cleaning her copper sink. It looked brand new, but she didn't want it to look like that. I would ask before cleaning any copper, bronze or brass.
I was asked to clean it. It has a vine cast into the sink that has a bunch of hard water build up on it. I'm doing the granite counters too. They have a bunch of deposits around the faucets. I will make sure they want the clean look in the sink before I proceed. Thanks for the heads up on that Cameron.