Tarnish around the rim of Horn

[mlane111]

Hey there experts. so i am restoring an old Horn and have some tarnish around the rim of the bell. (see pic) Based on what i have read i am guessing this may be from water? but seems this is due to the lacquer failing around the rim? Obvioulsy i want to clean this up - and have read about using brasso - But worry thats too harsh? also have Hopes Brass Polish? Curious what methods you might suggest to address this thin line of tarnish without impacting the rest of the lacquer on the bell?

Thanks in advance

IMG_7541.jpg

in case the attachemnt doesnt work here is a link....
https://www.dropbox.com/s/m3a7ghaha4zcv ... 1.jpg?dl=0

[tbonesullivan]

Is that a soldered rim? They very commonly get "acid bleed", where left over flux from the soldering process slowly leeches out over years / decades, damaging the finish and causing surface corrosion.

If that is not a soldered rim, it could just be from oxidation traveling from under the rim. The finish doesn't really get in there, so if corrosion happens in there, it then can lift up the edge of the lacquer and spread.

[BGuttman]

Regardless of the cause, the material you are showing is a copper oxide. It can easily be removed with white vinegar. I would use a Q-tip dipped in the vinegar and then rubbed on the green stuff. It should come off and stain the Q-tip green. When it is all gone, treat the area with a dilute solution of baking soda to neutralize any acid on the surface.

Once you have removed the crust, use the brass polish to shine up the area now exposed. It has no lacquer on it and will tarnish, so you might finish up with a coat of hard wax (I like Turtle Wax Hard Shell car wax). That will slow up the tarnishing.

[greenbean]

Alternatively, you could just leave the corrosion as it is. I kinda like it. It is part of the aging process. And trombone age especially well.

[Posaunus]

It is part of the aging process. And trombones age especially well.

As do trombonists!

[Blabberbucket]

Acid bleed from excess flux/acid leftover from the bead soldering/cleaning process. As other posters have said a chem clean or lightly abrasive polish of some sort will remove the oxides. it can be buffed and lacquered over if you're concerned with aesthetics. If aesthetics are not a concern, I wouldn't worry about it.