Lovely Brown Patina

[circusboy]

I was reading in an earlier thread about using various acidic surfactants to clean up raw brass. Sounded like good suggestions, but it raised a couple of questions for me:

1. It mentions removing the slides and pistons before cleaning, which makes sense, but I have rotary pistons and have never messed with them before. Anything in particular of which to be aware here?

2. So I get it all clean and maybe even a little shiny, how do I then get a nice even patina on it, both for looks and protection? I've shined both the inside and outside of the bell before, but ended up with a splotchy patina of brown, gold, black, and even purple--not pretty.

Thanks.

[Rick Denney]

1. It mentions removing the slides and pistons before cleaning, which makes sense, but I have rotary pistons and have never messed with them before. Anything in particular of which to be aware here?

2. So I get it all clean and maybe even a little shiny, how do I then get a nice even patina on it, both for looks and protection? I've shined both the inside and outside of the bell before, but ended up with a splotchy patina of brown, gold, black, and even purple--not pretty.

1. Removing rotors is not difficult but it helps if you can get someone who knows how to show you and look over your shoulder the first time.

You remove the stop-arm screw and then you can gently pry up and off the stop arm. Then, remove the rear cap. You can then tap the front rotor shaft with a rawhide mallet and it will drive out the rear bearing plate. When that is loose, the rotor will fall out, so be ready to catch it in your hand.

To install, slip the freshly oiled (with regular valve oil) rotor into place and then the rear bearing plate. Make sure the alignment marks are aligned. Then, using a wood dowel and a rawhide hammer, tap the bearing plate in place. Getting it seated so that it doesn't bind the rotor takes effort.

Then, oil the rotor bearings with light machine oil or rotor oil, and reinstall the rear cap. Then, tap the stop arm in place with a rawhide hammer, and reinstall the screw. Don't drive down the stop arm with the screw--the screw will break. Don't ask me how I know.

2. The only way I know to put a nice brown patina on brass is to fully polish it so that it is even and then allow it to age gracefully.

Rick "who uses Nevr-Dull to polish brass in preparation for slow aging" Denney

[circusboy]

Thank you, Rick. I have to say, the rotor thing sounds kind of intimidating. Is it as hard as it sounds? The last time they were touched was by Matt at Dillons. They've been working so beautifully that I'm afraid to mess up a good thing.

My last polishing attempt was with NevrDull. It seemed to take forever and completely exhausted me--and I ended up with the 'patina' described above . . . .

[Chuck(G)]

For a nice brown patina, treat the brass with "liver of sulfur" (potassium or sodium sulfide/polysulfide). It's a base, not an acid, so it won't corrode things. Google around a bit to find a supplier near you. You can vary the application to get anywhere from a dirty yellow to almost black.

[Dan Schultz]

Thank you, Rick. I have to say, the rotor thing sounds kind of intimidating. Is it as hard as it sounds? The last time they were touched was by Matt at Dillons. They've been working so beautifully that I'm afraid to mess up a good thing....

You need to take your horn to a reliable repairman and watch carefully while he removes the rotors. Ask questions. This IS NOT an area for experimentation. Getting the rear bearing plates back into the rotor casing squarely is easy, but you need to know what you are doing.

NEXT TIME you can do it yourself.

[Chuck(G)]

Is that not the same stuff used in museums? Could you PM me very specific, idiot-proof instructions to do this that I could forward to a friend in Japan (you will be credited, of course). By idiot-proof, I mean in very basic English. (Then I will be able to follow them, too!) Our principal trombonist is from Japan and is home for the summer. He emailed me this very question two days ago. His English is now up to "moderately serviceable" (which is faaaaar better than my Japanese). He will have to translate this for his buddy.

Basically, it goes like this:

http://www.sculptnouveau.com/monthly100.html

Oh--and do it where there's ventilation--the stuff stinks something awful.

[TonyZ]

To get a good patina, use "Funky Cold Medina"



...sorry

[dwaskew]

Jeff Funderburk, prof. at Northern Iowa, has this video online:

http://www.uni.edu/drfun/repair_video/r ... index.html

which takes you through the steps of disassembly and maintenance of rotors.

[circusboy]

Thanks, everybody. Great information!

[Rick Denney]

Basically, it goes like this:

http://www.sculptnouveau.com/monthly100.html

Oh--and do it where there's ventilation--the stuff stinks something awful.

Have you gotten even results doing this on something as big as a tuba? My results from when doing this on larger antique clock parts was rather tiger-striped at best, unless I took it all the way to black. And I don't want to rub it with a wire brush to even it out as suggested at your link, though I think it looks good on antique furniture hardware.

Rick "thinking it isn't quite as easy as it sounds" Denney

[Chuck(G)]

Have you gotten even results doing this on something as big as a tuba? My results from when doing this on larger antique clock parts was rather tiger-striped at best, unless I took it all the way to black. And I don't want to rub it with a wire brush to even it out as suggested at your link, though I think it looks good on antique furniture hardware.

Does a euphonium count?

The trick is having everything squeaky-clean when you start--no fingerprints, tarnish, etc. A bath in some warm water and detergent might help get the remaining oil off.

I don't think I'd use a wire brush, but some 000 steel wool or bronze wool (which is what I used) does help a lot to keep things nice and even.

FWIW, I made up my own patinizing solution by mixing dormant oil spray (basically sulfur and oil) with a hot lye solution. It worked just fine.

One advantage of this is if you're not happy, just polish the artificial tarnish off and start all over again.