I had my trumpet overhauled everything silvered except the bell, which was left raw brass. I'm not sure of the correct word, but I think it's not "oxidizing" evenly over the bell. It there anything I can do to 1. help the process of "turning" and 2. how can I get it to be even across the whole bell? I really like the looks of the raw brass Monette trumpets and thought mine would turn out looking like that. Any help would be appreciated.