How do I clean and seal copper roofing?

Question

Sealing copper cupolas, sealing copper gutters,
preserving shiny copper

Answer 1

From a thread on Finishing.com:

"If the roof has not been painted I would suggest a stiff brush and a mildly acidic solution, there are a great number of things available that will work just fine provided you are willing to put in the elbow grease (ketchup is an unusual example, but it does work!) If you are looking for something that will not ruin the lawn or plants around the roof I suggest Kool-Aid or some other powdered drink mix, mix it with a bit of water, rub it on and scrub with a will, it's mildly acidic and non-toxic to the plants that you may have below the roof, the first rain will remove the sugary coating that is left when it dries (or just rinse with water). If you are intent on the copper staying bright I suggest looking for a clear spray on lacquer (test it somewhere it won't be seen first). Your local hardware store will have what you need."

Try the link below for the rest of the thread to see what else people there had to say. Good luck!