Yes....close......but here's the more apropos and complete article of the two:
...you can gloss over the middle part, which is a huge ~ albeit interesting ~ digression about burnishing....
My 2 cents...if it is already bare brass, DON'T USE BRASSO. It is too aggressive. It's great for getting off really nasty stuff on vintage instruments...red rot and the like....it can even dissolve old lacquer. But if what is going on is the fact that the horn is not patina'ing the way you'd like and there is some discoloration, here is the best course of action:
If you are not gonna DIY, take the horn to tech and have him/her give the body a chem bath or sonic bath.
If you are gonna DIY and know how to disassemble a horn, start with a soap and water bath with a gentle sponge, & perhaps a biodegradable dishwashing soap. Dry it thoroughly using a microfibre cloth and hairdryer. Then use WENOL instead of Brasso. It is gentler, less abrasive yet still cuts through quite nicely.
If you encounter bad areas (red rot or the verdgris you mention) spot use Brasso there, but not the whole horn. Wenol gives a nice sorta matte shine. If, afterward, you are unhappy with the sheen of the brass, then hit it with Hagerty 100 polish, which will give it a mirror-like shine and actually will initially make it appear to be a newly-lacquered horn.
The nice thing about both products is that (more often than not) as the horns then patina, they do so in a much more uniform way.
Then it is all up to you to keep the horn dry and clean after the polishing is done. Verdgris and red rot are the results of water/spit/sweat sitting on the bare brass, oftentimes left there when you put the horn away. Proper swabbing and occasional polishing with a silverplate polishing cloth (great for bare brass because the rouge with which it is embedded with is very, very fine) is also your responsibility.
Also: 1) for future reference, do not experiment with a polish on so prominent an area as the bell. Spot apply it someplace which is not as visible.
2) using a paper towel is akin to using a cotton t-shirt rag, which is akin to using 0000 steel wool....all of which are a bad idea. Get a nice microfibre cloth for glas
s, available at most any hardware store and quite a few supermarkets, too. Best not to use paper products to polish your horn.