What is this stuff on the bell?

[Jim2195]

I’ve noticed multiple “rusty” splotches amidst the scratches on my trombone. I have no clue what this stuff is, as it doesn’t look like typical lacquer wear to me. Additionally, is there a way to remove it? Thanks in advance to anyone who has answers!

[greenbean]

I think you are looking at areas that have lost lacquer due to dent removal. The raw brass then corroded a nice red color. Pretty much harmless corrosion - not "red rot." It can be removed easily. I have used Bon Ami or Bar Keepers Friend, and I imagine brass polish would work.

[hornbuilder]

what he said

[Jim2195]

I think you are looking at areas that have lost lacquer due to dent removal. The raw brass then corroded a nice red color. Pretty much harmless corrosion - not "red rot." It can be removed easily. I have used Bon Ami or Bar Keepers Friend, and I imagine brass polish would work.

Thanks! I’ll see if I can get ahold of the products you mentioned and try them out.