Nevr-Dull works well for polishing brass.
To maintain the polish keep using Nevr-Dull, Brasso, Simichrome,
rouge, Sunshine cloth, or one of the many other polishing products on
a regular basis, or coat it with a lacquer/preservative of some sort.
I was a Marine for 27 years. At least once per duty day, if not
more, I had to polish the brass items on my uniform, as did every
other Marine. Believe me, if there was a way to maintain the polish
without having to polish it every day we would have found it.
Mike DeBurgh, GJG