Over my bay window is a copper roof. Unfortunately the roof above doesn't have gutters yet. Where the water drops on the hip roof it is discolored. What is the best way to get this looking good again?
Just wait a while longer and you'll get lovely verdigris green. The copper oxides actually help protect the roof. But depending on yout local atmosphereic conditions getting from brown/black to green can take quite a while.
Or hire someone to give it an acid treatment to accelerate the process. There might be DIY options there, I'm not sure.
If you polish and clearcoat you'll just be fighting the clearcoat peeling off for the rest of your life, or until you sell the house.