I just picked up a 55 Olds Recording that has most of the finish gone already. The bell has a beautiful dull patina that I love. I don't want to have it re-plated, I just want the whole horn to look the same. There are a few places on the silver and brass areas that have spots of shiny plating on it and I want all of it to have the same look. What is the safest way to do this myself?