Removing black water spots from brass

[Steve Sykes UK]

Hi all

just bought an old German tuba.
I've given it a good old clean and the brass is looking good - but for the dreaded black water spots down the bell.
I've tried my best to shift this stuff but nothing has worked yet - anyone got any advice on getting rid of this stuff.

Thanks in advance.

[Locky]

Responses awaited with interest please. My endeavours finished with metal polish which sends the patina to hell in a hand cart!

Locky

[Steve Sykes UK]

Hi Bloke

thanks very much for your reply.

Is the sandpaper likely to do much noticeable damage to the finish ?

Cheers

Steve

[The Big Ben]

Is it better to wet sand or dry sand? My first guess would be wet, like with painted surfaces.