One more raw brass question

[Chuck(G)]

Yup. The chemical agent is called "Liver of Sulfur" (Potassium Polysulfide) will produce a brownish finish.

The stuff's caustic and can emit hydrogen sulfide gas (which is toxic), so wear gloves and work in a well-ventilated place.

You can get anywhere from a straw to almost black finish. However, the result won't look completely authentic if it's applied on highly-buffed brass (i.e., it'll be dark, but still will be glossy), so you may have to use some 000 steel wool to dull the finish first.

Here's one place that carries it:

http://www.misterart.com/store/view.cfm ... ID=1561714

...or you can simply let the tuba darken on its own

[Chuck(G)]

Any idea what it will do to nickel silver ferrules and slide tubes?

It will dull them somewhat, but the good/bad news is that potassium polysulfide doesn't react as much with nickel-silver as it does with yellow brass (nickel-silver is also a brass, just not yellow). In any case, if you want them to be shiny, just polish them.

[Daniel C. Oberloh]

In my previous life working in the plating biz, we had a one-thousand gallon tank of liver of sulfur. it is a neat chemical (but nasty) and if employed by someone who has a lot of experience working with that particular batch of chemicals, the results can be quite impressive. A brass instrument that is well polished and that has nickel silver trim achieves a very good look when treated with this process. My experience is limited but I did spend a little time processing brass plated parts and running them through the stuff. It is a sensitive chemical and a touchy process that is in a constant state of flux (it drove the company chemist up the wall). imagine a tuba the color of dark chocolate that also has a mirror finish, accented with nickel guards, levers and wreath, not something you see every day. The down side is that it still needs to be degreased and lacquered or it will simply look like crap in no time. I guess what I have added here is of little value seeing that the original poster is talking economic issues. I still don't see the savings in stripping the horn, its more work, that takes time and time is.... well you get the idea.


Daniel C. Oberloh

Oberloh Woodwind and Brass Works
Saving the world one horn at a time...

www.oberloh.com