TromboneChat

Got a Yamaha with red brass that has rot on the edge. Lacquer is good everywhere else. How do I clean it?

Note: Red Rot is a specific condition where the brass loses zinc. It's almost never seen on bell rims. Also takes decades to manifest itself.

What I think you have is "acid bleed". You probably see black under the lacquer near a solder joint. This is caused by not cleaning the flux well after soldering the joint. It's not something you can easily clean off. It's a discoloration of the brass under the lacquer. In order to remove it you need to remove the lacquer and then sand the bell to remove the oxidation. You may do permanent damage to the horn if you are clumsy with this.

If this is a new horn, you may be able to exchange it for one with no acid bleed. If it plays well, you may just consider leaving it and playing it as is. I have a horn that developed acid bleed in the first month and it went to a certain point and just stopped. It's been that way for 20 years now.

Yes, you are correct. It is acid bleed. Thank you.

Seems this issue is more on pro horns, I rarely (if ever) see a student horn with acid bleed along the edge of the bell rim. Not sure why that is.

Bach42t wrote: ↑Sat Dec 15, 2018 11:55 am Seems this issue is more on pro horns, I rarely (if ever) see a student horn with acid bleed along the edge of the bell rim. Not sure why that is.

The most ubiquitous student horns I can think of (YSL 354 and King 606) both - as far as I can tell - have an unsoldered bell bead. Professional horns have more of a mix of soldered and unsoldered bell beads. My understanding is that the flux expands under the lacquer, which is what causes it. Ergo, if there is no solder, then you won't get acid bleed.

Bach42t wrote: ↑Sat Dec 15, 2018 11:55 am Seems this issue is more on pro horns, I rarely (if ever) see a student horn with acid bleed along the edge of the bell rim. Not sure why that is.

To draw inspiration from the Bone Wars Youtube video series:

"So you know it has hand-crafted bell!"

If it’s a red, gold or rose brass bell, it’s not likely red rot. Red rot usually only affects yellow brass.

BGuttman wrote: ↑Tue Nov 27, 2018 6:12 am Note: Red Rot is a specific condition where the brass loses zinc. It's almost never seen on bell rims. Also takes decades to manifest itself.

It usually does take decades. Except on Yamahas. I’ve probably seen 8-10 in the last half dozen years that developed red rot on the outer slide within 5 years. In fairness, I haven’t seen it on a bell. I have seen pink spots under lacquer on other brands that were finishing flaws also.

80% of the time it is moisture dripping out of the slide section onto the bell when the horn is in the case and standing on end. 20% of the time it's an acid bleed.

When I was building horns at the King Eastlake Ohio plant we had a stretch of horrible acid bleeds on bell rims and guard wires!

Red rot is a serious condition which usually manifests itself on outer slides. I had two Bach horns that developed this issue within about 5 years of ownership. Both required overhauls (new outer slides).

It's probably an accurate assessment that discoloration near or on the wire rim is acid bleed, flux which was not thoroughly cleaned off before lacquering. It usually doesn't affect the integrity of the horn, unlike red rot, which will eat through the metal.

I have a twenty-something bass trombone with a small acid bleed spot near the rim wire that's been there unchanged for almost the entire life of the horn. It's obstructed by the bell flare, so I don't see it while playing. Out of sight, out of mind!