Artillery sees light of day after 47 years

[DavidJayUden]

Depends. If you are a seller, then it is called patina. If you are a buyer it is called rust.
To me a course cloth and gun oil is where you start, then go towards the very finest steel wool with a generous coating of oil, being very cautions as you go. There may be a bronze or brass pad that is even less aggressive than 00000 steel wool.
Let's see what the others say.
dju