Mike, I know what will work because i use it to clean the inside of domestic copper hot water systems. The product will clean the copper to look like new. However you will have to test it on the brick to see what effect it will have on it. Or you can cover up the brick when you use it. the product is called "Unlime" sold by plumbing suppliers that sell A.O.Smith water heaters. Its safe to use and is a mild acid much like the acid in oranges. I read the MSDS reports and the hazzards are non existing. it washes off with water. After cleaning the copper you will need to seal it with probably a lacquer finish, and keep resealing the copper as the time goes by or it will dull to a dark brown and or the normal color of copper which is green when it comes out of the ground. You choose good luck, brAin, get a book on copper at our web page "paich.com"