Cleaning a brass/brass look frame

[Ohfuckohfuckofuck]

Bought a 'vintage' Art Nouveau style frame (so lots of detail) in brass or brass effect. It's got a fair bit of patina on it. Whilst I like the aged look, I'd like to clean it up a bit.

What home product can I use that won't be too abrasive?

ketchup! It works and if you let your kids eat it it should be ok for metal.

Lovely, thank you.

Came up a treat, thank you.

Great, I learnt it on here