Staining on pistons

_Mark_

I picked up an old horn with sticky valve slides. It wasn't well cared for and the price was right. There is an indelible staining on the pistons. I've tried an alcohol bath and this cleared the gunk from the passages going through the pistons, but not the black stains. Any suggestions?

Newell Post

Chemical cleaning. Soak the pistons for a limited time in a mild acid solution. Details are discussed elsewhere in TM.
Mild hand lapping with very fine abrasive lapping compound. Also discussed elsewhere in TM. Lapping can also improve the sticky slides.

Do not try these things at home on any instrument of any real value, unless you have training in how they are best done. If it is a mostly worthless "project horn" for experimenting and fooling around, have at it.

Trumpetsplus

If the pistons work well, don't worry about discoloration. The thickness of the colored coating may be working to compensate for valve wear.

This talks about that https://www.jaegerbrass.com/Blo/Entries/2017/1/exposing-wear---dont-shoot-the-messenger.html

_Mark_

@trumpetsplus just a little sticky sometimes. I think the issue are the guides. I'm trying to figure out a safe tool for scraping lightly in the guides. I was hoping that the lubricant would dissolve some of the gunk, and maybe it eventually will. I'll just keep playing, cleaning, and lubricating for now.

Trumpetsplus

If they are fixed guides on the piston running down a slot in the casing you might try rubbing a wooden popsicle stick up and down down the slot. Be aware, any more work and it might end up like my '36 Ford!

J. Jericho

@_mark_ Although a shiny horn is nice, shiny valves are not a goal one should seek. Most stains are inconsequential, other than the situation that Ivan described. Some players think polishing valves is a good thing. They are wrong; polishing valves to remove stains and scratches removes material, i.e. accelerates wear. Not a good thing. If the valves are sticking, the true cause must be determined before action is taken to correct the problem.

You mentioned sticky valve slides. Did you mean valves?