There are many "schools", but personnaly I clean.
Rust and oxidation are not patina for me, so I clean my knives.
Especially if it is green oxidation, it is easy to clean to "new" copper and brass, but it also easy to make old with specific products.And you don't need a long time to have a soft matt, unpolished patina, which is better,for me , than a bad green.
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