TromboneChat

A small section of my F-attachment has red rot.
The instrument has been in continuous use since about 1957.
Will removing the F-attachment tuning slide when packing in the case help to slow the progression?

Probably not. Removing the slide and draining any moisture will work better. Then you can put the slide back in.

I would suggest having a patch put on the area for structural integrity. If it's tubing, a replacement or even a ferrule put over the bad area can help.

Throw it all away, buy a new one.

I saw a study at this historic brass society symposium a few years back where they used a small fan to provide airflow through an instrument to dry it out after playing, and the difference in the condition of the brass after just a few months between an instrument this was done with and one it was not done with was stunning. Perhaps removing the tuning slide would help remove moist air and condensation on the inside of the tubing. Also make sure the tubing is clean, so that there isn't anything holding moisture against the tubing. Even just getting something like a flute pad-saver swab and running it through that tubing before putting it away can do a lot. Have you been able to confirm from the inside that it really is red-rot (coming from the inside) rather than just surface corrosion, coming from the outside?

A master technician once told me that red rot is like a football player with an injury. If a single defensive player makes a tackle and the running back breaks a bone in his leg, it might just be a hairline fracture.....that is similar to red rot starting in a brass instrument. I'm not in the medical field, but I imagine that many players can get the proper treatment for the crack in a bone and return to their sport with the proper healing time.

If the entire defensive team piles on after the tackle and somebody in the pile twists the running back's leg, the hairline fracture can be become an oblique/displaced fracture and possibly a compound fracture (breaking through the skin).....this is what happens if you see red rot and do nothing about it. The oxidation of the metal will get worse and worse and eventually become a large enough hole in the metal that it leaks.

An instrument can function perfectly with small areas of red rot for many years. So....It is best to take measures to control or "mitigate" the red rot. The two best things to do are (in combination with each other)..... 1. A chemical clean to prevent the lime scale and calcium build-up spot from growing/spreading. 2. Scrub the internal area with a brush and pumice soap mixture. This will, just like the chemical clean, reduce the lime scale and calcium build-up that festers and turns a microscopic hole (small amount of red rot) into a huge-hole disaster.

I have a few customers who own vintage instruments with small amounts of red rot. They bring their instruments to me about once a year for a mild chemical treatment and internal pumice scrub. On all of these instruments the red rot has remained fairly stable and the instruments continue to play very well. Eventually the red rot spots will become holes. However, a good maintenance plan will make it so the metal will last decades instead of months or single years.

Air ventilation will slow the onset and spread of red rot. Moisture is one of the things that fuels oxidation in all metals.....even non-ferrous alloys like brass.

I forgot to mention that ultrasonic cleaners are NOT good for brass instruments with red rot. Those machines can turn the red rot spots into larger holes. That is why I recommend the chemical cleaning + pumice soap scrub.

Once red rot starts, there is really nothing to do to "mitigate" the progress.

The thoughts of keeping it dry are OK, but not foolproof.

DEFINITELY NO ultrasonic cleaning!!!! And best to not use any chemicals beyond mild dish soap!!!
Maybe a clear water rinse regularly, and a squirt of valve oil into the slide to coat the crook, but that's it.

As mentioned, a shaped patch or replacing the crook might be in order, eventually. But if it's been OK since '57, I think you'll be OK for a few more years!!


Eric

Bonearzt wrote: ↑Tue Aug 18, 2020 7:57 pm Once red rot starts, there is really nothing to do to "mitigate" the progress.

The thoughts of keeping it dry are OK, but not foolproof.

DEFINITELY NO ultrasonic cleaning!!!! And best to not use any chemicals beyond mild dish soap!!!
Maybe a clear water rinse regularly, and a squirt of valve oil into the slide to coat the crook, but that's it.

As mentioned, a shaped patch or replacing the crook might be in order, eventually. But if it's been OK since '57, I think you'll be OK for a few more years!!


Eric

In terms of the word "mitigate," you are correct Eric. You cannot reverse the negative impact of red rot, but I definitely think that a calculated plan can slow down its destructive path.

Back in the early 1990s (before I started doing tech work), I sent one of my old Conn trombones to Chuck McAlexander (BrassLab in NYC). I wanted him to replace a couple of parts because there were small areas of red rot. He thought that the horn would have more value if we kept the original parts/lacquer and suggested that we monitor the red rot with regular chem cleans and internal scrubbings with pumice soap. That advice stuck with me until today and that particular horn still has all of its original parts (the red rot has only progressed the slightest bit).

Eric does not recommend any chemicals and I can understand his concerns. I think chemicals can be used on horns with small amounts of red rot, but ONLY if the acidity is correct. My primary acid tank has very low acidity compared to most techs. Some day I should actually measure the pH. The low acidity allows me to control the impact the chemicals have on the metal to a very high level. I can put something in the tank for 5 minutes and check it, back in the tank another 5 minutes and check it, etc..... It is nice because there is only a slight change each time. The downfall is that sometimes it takes forever for my chemical solution to remove large amounts of lime scale and calcium in the really nasty instruments.

Chemical tanks are never perfect for every job. The stronger mixtures can remove a lot of build-up in about 5 or 6 minutes. Removing that same amount of build-up might take 35-40 minutes in my acid tank. However, a weaker acid mix does give you the flexibility to manage delicate situations like the horns that have some red rot.

Burgerbob wrote: ↑Tue Aug 18, 2020 1:23 pm Throw it all away, buy a new one.

I'm going to assume this is a joke. The instrument is irreplaceable and it plays and sounds like no other.

bbocaner wrote: ↑Tue Aug 18, 2020 1:41 pm ... they used a small fan to provide airflow through an instrument to dry it out after playing ...
make sure the tubing is clean, so that there isn't anything holding moisture against the tubing ...
... Have you been able to confirm from the inside that it really is red-rot (coming from the inside) ...?

I'm responding to the extracts from your comments.

When I had it chemically cleaned a few years ago the highly-respected technican told me it was red rot. I trust his opinion so I'm confident it is red rot. He also said nothing could be done to stop it. But I was hoping maybe to slow it down by keeping it dry. Unfortunately the F-attachment wrap is "closed" (no air in or out) when stored so the fan idea would be complicated. Making matters worse: the part of the traditional wrap that has the red rot is not easily accessible.

Crazy4Tbone86 wrote: ↑Tue Aug 18, 2020 4:38 pm ... The two best things to do are (in combination with each other)..... 1. A chemical clean to prevent the lime scale and calcium build-up spot from growing/spreading. 2. Scrub the internal area with a brush and pumice soap mixture. This will, just like the chemical clean, reduce the lime scale and calcium build-up that festers and turns a microscopic hole (small amount of red rot) into a huge-hole disaster. ...

Thanks. I'll ask my local technician to do just that.

Other things being equal, IMO moisture is the enemy of brass.

I don't see how a horn is going to dry out packed in a case. If children, pets, and general clumsiness allow I think the best storage is probably on a stand with outer slide pulled off and hung on the handslide brace. I started doing that with my pBone mini because it can't handle being wet, but now do it with my straight tenor also. But nobody but me goes in that section of the basement.

A hollow stand with a fan that blew air through is probably even better but you'd have to construct it.

It didn't occur to me until just now, but you could also pull the tuning slide or slides. With a trigger though there's probably a loop somewhere that a drop will sit.

patrickosmith wrote: ↑Wed Aug 19, 2020 6:01 am

Burgerbob wrote: ↑Tue Aug 18, 2020 1:23 pm Throw it all away, buy a new one.

I'm going to assume this is a joke. The instrument is irreplaceable and it plays and sounds like no other.

Discussing red rot with brass players is like discussing politics with strangers......beware. People can feel very strongly about removing it or completely passive about its existence.

My brother (a trumpet player) hates having any red rot on his horns. He brings them to me in a panic and wants the rotted part replaced immediately. On the other end of the spectrum.....I know a good euphonium player who has so much red rot in his leadpipe that he has it wrapped up with electrical tape. His philosophy is.....play it until it doesn't work any more.

What’s the harm in just replacing the part?

Elow wrote: ↑Wed Aug 19, 2020 9:35 am What’s the harm in just replacing the part?

Grandfather's axe.

Many people feel that an Elkhart Conn is no longer an “Elkhart Conn” if you replace some of the components with modern parts. You can plug any vintage of an assortment of brands into that previous sentence.

What’s the point of having an elkhart conn if you can’t play it, but i guess that’s the problem of whoever’s the owner in 15 years

You CAN play an instrument with red rot. That was what the initial inquiry was all about. He knows he has red rot and apparently the instrument still plays very well. He wanted to know if there are any "tricks" to slow the spread of red rot. There is some mild disagreement on whether or not a person can do things to slow the red rot, but the musician appears to want to keep the original parts. The original poster can take any of the assorted advice or leave it.

Red rot must be in a very advanced form before an instrument starts to have leaks and is rendered unplayable. I don't have any statistics, but I am imagine that a large percentage (possibly 20-25% or higher) of the world's brass instruments have red rot......most of them are still very playable.

Elow wrote: ↑Wed Aug 19, 2020 9:35 am What’s the harm in just replacing the part?

Spare parts don't exactly exist for a lot of vintage horns. The surgery to get a particular part out may be quite extensive as well.

To the OP, I think you are doing a not insensible thing by just monitoring it. As said above, it has made it a few decades, it will probably do some more. I would think that you should have an answer for what you would do right now to repair it. Try and replace the part, or try to patch it? The answer can change, but figuring out the process to make the decision and what factors you want to consider will help if you ever need to make that as a final decision in the future.

Cheers,
Andy

Does anyone ever drill out the spots (suitably large diameter to catch the unseen progress of the rot), then rivet in a patch, file it smooth and continuous, maybe with some silver solder for good measure?

baileyman wrote: ↑Thu Aug 20, 2020 3:07 pm Does anyone ever drill out the spots (suitably large diameter to catch the unseen progress of the rot), then rivet in a patch, file it smooth and continuous, maybe with some silver solder for good measure?

Normal procedure is to solder on a patch larger than the spot. The solder will arrest the spread of the rot. Also, the patch must be bigger because you can't solder to the red rot.

Don't you have a patch on the slide bow of your Bach 9?

Rivet?

Doug Elliott wrote: ↑Thu Aug 20, 2020 3:44 pmRivet?

Oh goodness! We know the rivets would become loose. Now we are inventing a trombone that doubles as a vibraslap!

BGuttman wrote: ↑Thu Aug 20, 2020 3:18 pm

baileyman wrote: ↑Thu Aug 20, 2020 3:07 pm Does anyone ever drill out the spots (suitably large diameter to catch the unseen progress of the rot), then rivet in a patch, file it smooth and continuous, maybe with some silver solder for good measure?

Normal procedure is to solder on a patch larger than the spot. The solder will arrest the spread of the rot. Also, the patch must be bigger because you can't solder to the red rot.

Don't you have a patch on the slide bow of your Bach 9?

Roy Main's 12 has a nickel silver bend soldered to the silver plated brass crook down there, but I think it's for protection rather than repair. Could be wrong.

Is there a chemical reason solder acts that way?

What happens is that the solder prevents the red rot from migrating to the patch. Red rot is caused by something (usually moisture with some acidity) extracting the zinc from the brass. There's no zinc in the solder (and no copper either) so it acts as a barrier to the red rot.

I thought the patch might have been a repair from too aggressive use of a cleaning rod. It's right about where a cleaning rod would hit the crook.

Doug Elliott wrote: ↑Thu Aug 20, 2020 3:44 pmRivet?

Sure. Say you can drill out the rot with a 1/4" bit. Then insert a small piece of 1/4" brass rod. At this point, silver solder it in or not (not sure). Continue, using a suitable anvil and hammer, pound the disk, expanding its diameter (riveting). Then file the disk flat in contour with the surrounding metal.

This could be a good repair, but I have not heard that anyone does this.

BGuttman wrote: ↑Thu Aug 20, 2020 5:04 pm ...I thought the patch might have been a repair from too aggressive use of a cleaning rod. It's right about where a cleaning rod would hit the crook.

If one inserts carefully to find the end at the crook, then chokes up on the rod, one can flail away with abandon. Don't choke up? Ventilate the crook.

baileyman wrote: ↑Thu Aug 20, 2020 5:06 pm

Doug Elliott wrote: ↑Thu Aug 20, 2020 3:44 pmRivet?

Sure. Say you can drill out the rot with a 1/4" bit. Then insert a small piece of 1/4" brass rod. At this point, silver solder it in or not (not sure). Continue, using a suitable anvil and hammer, pound the disk, expanding its diameter (riveting). Then file the disk flat in contour with the surrounding metal.

This could be a good repair, but I have not heard that anyone does this.

Great idea in theory, but it would probably be a disaster. The 1/4' insert of any material would have much more mass than the thin brass tubing. I can guarantee you that the brass would start collapsing with the first tap of the hammer.

Also keep in mind that the areas around the red rot are probably compromised on the inside with corroded metal that has not come all of the way through. The tubing would be exceptionally thin and susceptible to collapsing.

baileyman wrote: ↑Thu Aug 20, 2020 5:06 pm

Doug Elliott wrote: ↑Thu Aug 20, 2020 3:44 pmRivet?

Sure. Say you can drill out the rot with a 1/4" bit. Then insert a small piece of 1/4" brass rod. At this point, silver solder it in or not (not sure). Continue, using a suitable anvil and hammer, pound the disk, expanding its diameter (riveting). Then file the disk flat in contour with the surrounding metal.

I don't see that working. If it were mechanically possible, which it isn't, it would leave a lump inside and a nice smooth surface outside. That's the reverse of what we would want. Also this is an F attachment, and the red rot is likely on the wettest place, which is probably a place where you can't get a mandrel inside.

I think a patch nicely soldered on the outside would prevent a future leak, as would a layer of JBWeld. (running for cover now)

BGuttman wrote: ↑Thu Aug 20, 2020 5:04 pm What happens is that the solder prevents the red rot from migrating to the patch. Red rot is caused by something (usually moisture with some acidity) extracting the zinc from the brass.

Kind of a nitpick, but I think the moisture facilitates the zinc extraction by allowing electrical current, rather than directly causing it as in dissolving.

Most of what I have seen on trombones has been on the lower part of the outer tubes and on the crook- small red spots that can have a central dot. If you wish to lessen the associated development of oxidation inside the outer tubes you should make sure your slide is dry and lubricate it well with something like trombotine or superslick that will coat the inside of the outer slides before you put it up. You might also try storing the slide upside down so moisture won't accumulate between the stockings and outer tubes. If a horn is not being played you should get it out periodically to wipe down the inners and relubricate. I have a Getzen slide that has had the same tiny red spots for about 20 years and the worst part of it is that the outer slide needs to be buffed out to make it smoother. Eventually the corrosion will come through from the inside and make a small hole in the outside of the slide but is a slow process. Something you play all the time may progress faster. I am having my favorite Bach 50 (1978) slide rebuilt with new outers and crook so it can be smooth consistently and operate with less frequent lubrication.. It is a shame that our favorite slide material, yellow brass, is the only material we use for slides that has this problem. Neither nickel tubes or gold tubes are susceptible.

I have seen plenty of nickel-silver tubes and gold brass tubes with red rot. Those alloys are less susceptible to red rot, but not immune.

The best way to store an instrument is absolutely dry. I have seen brass instruments stored dry for 15+ years and they were in perfect condition and ready to use instantly upon removal from the case. Of course storing an instrument completely dry does take some energy. I swab my instruments several times and then do a few rounds of vacuuming to make them dry before storage.

I have also seen new instruments played for a short amount of time (thus, they have moisture in them), stored away in a case for a couple of months and they developed red rot. These particular instruments were made of a brass alloy that seems particularly susceptible to red rot. I'll refrain from mentioning brand names to protect the innocent.

Crazy4Tbone86 wrote: ↑Fri Aug 21, 2020 11:21 am I have also seen new instruments played for a short amount of time (thus, they have moisture in them), stored away in a case for a couple of months and they developed red rot. These particular instruments were made of a brass alloy that seems particularly susceptible to red rot. I'll refrain from mentioning brand names to protect the innocent.

? Who's "innocent?" Why not let us know which instruments / which alloys need special care?

There are chemical treatments you can apply to brass that will reduce corrosion (and hence red rot). Problem is, many are not terribly environmentally friendly or RoHS compliant.

I'm no metallurgist. Is "red rot" merely brass corrosion (oxidation) – or is there a galvanic aspect to this phenomenon?

Hey Posaunus,

I'm not big on smack-talking any brands. I believe that any company can have good years and bad years. I also believe that companies can start with an inferior product and work very hard to improve it. Obviously, the opposite can happen as well.

Since the particular brand in my thoughts actively sought to improve their products through research and feedback from technicians and players, I have a great deal of respect for them. They presently use higher grade brass than they used 15-20 years ago and I think they made many decisions that improved their products. I choose to not identify them and keep the masses guessing!

That being said, I'm sure some of you can point out that I have criticized some "high grade" brands for having bad alignments in their slides and bell sections. I think poor alignment is an industry issue and not a problem for just specific brands. It is only something that I became aware of after I started doing tech work and building horns. I actually played for 25 years thinking that EVERY trombone was built precisely to the 1/1000th of an inch. Ignorance was such bliss!

Posaunus wrote: ↑Fri Aug 21, 2020 7:33 pm I'm no metallurgist. Is "red rot" merely brass corrosion (oxidation) – or is there a galvanic aspect to this phenomenon?

Red rot is caused by the copper-zinc alloy losing its zinc. It's not corrosion per se, although corrosion has a galvanic aspect as well. Removal of zinc from copper alloy can be caused by acid contact, galvanic action between local cells rich in copper or zinc (different electropotentials resulting in the de-zincification), or solid state reactions with other materials in contact with the brass.

When the zinc is removed from the brass alloy, the remaining copper is oxidized and is not solderable. It also is very brittle, which is why holes develop easily.

This is not galvanic action like electroplating. There's no battery or wires involved.

BGuttman wrote: ↑Fri Aug 21, 2020 8:49 pm
When the zinc is removed from the brass alloy, the remaining copper is oxidized and is not solderable. It also is very brittle, which is why holes develop easily.

This is not galvanic action like electroplating. There's no battery or wires involved.

I think it is probably galvanic, but as you say caused by the different metal potentials.

But what may not be obvious is that brass has a grain structure. The zinc is lost preferentially at the grain boundaries. Picture a honeycomb or maybe a soccer ball that is tiled with small grains, and you're losing the metal where they connect. You can see why it weakens the structure and you're going to have trouble soldering.

patrickosmith wrote: ↑Tue Aug 18, 2020 12:21 pm A small section of my F-attachment has red rot.
The instrument has been in continuous use since about 1957.
Will removing the F-attachment tuning slide when packing in the case help to slow the progression?

Use of rubbing alcohol as a drying agent before storing?

Ok, I don't have all the answers but I don't think we are getting everything straight here. #1 Isn't brass rot dezincification? Nickel silver doesn't have any zinc in it, does it?
#2 Don't assume any little red spot you see is red rot. Often it is just where corrosion forms under the lacquer, where the brass had not been perfectly cleaned or whatever in the preparation stage. #3 A big clue is location, usually somewhere water can collect, like the crook or between slide stocking and tube. #4 Young players needn't picture their horn rotting or cancer- like spreading; brass rot leads to a tiny pinhole forming from inside. It can be patched. What can't be fixed is the more rapid than normal formation of corrosion or scaling inside a tube after it gets an internal polshing. #5 My source on "gold brass doesn't get brass rot" was M/K Drawing & Bending, and one would think they would know. Just saying, we may need more authoritative posts on things than we are getting.

btone wrote: ↑Sun Aug 23, 2020 7:40 am Ok, I don't have all the answers but I don't think we are getting everything straight here. #1 Isn't brass rot dezincification? Nickel silver doesn't have any zinc in it, does it?

Nickel silver has no silver in it. It's an alloy of copper, nickel, and zinc. But if it de-zincifies, it won't turn red.

btone wrote: ↑Sun Aug 23, 2020 7:40 am #2 Don't assume any little red spot you see is red rot. Often it is just where corrosion forms under the lacquer, where the brass had not been perfectly cleaned or whatever in the preparation stage.

True. The way to test is to polish the spot a little. If it disappears it's a "rust spot" (rust refers to iron, this really is just oxidation).

btone wrote: ↑Sun Aug 23, 2020 7:40 am #3 A big clue is location, usually somewhere water can collect, like the crook or between slide stocking and tube. #4 Young players needn't picture their horn rotting or cancer- like spreading; brass rot leads to a tiny pinhole forming from inside. It can be patched. What can't be fixed is the more rapid than normal formation of corrosion or scaling forming inside a tube.

Regardless of where it starts, red rot is a VERY slow process. Usually takes decades to do any real damage. Unless you leave the horn with acids inside.

btone wrote: ↑Sun Aug 23, 2020 7:40 am #5 My source on "gold brass doesn't get brass rot" was M & K, and one would think they would know. Just saying, we may need more authoritative posts on things than we are getting.

Higher copper alloys (gold brass, rose brass, red brass) have less zinc, so they would red rot much more slowly. Bronze is an alloy of copper and tin, and as such wouldn't red rot at all.

Crazy4Tbone86 wrote: ↑Fri Aug 21, 2020 11:21 am I have seen plenty of nickel-silver tubes and gold brass tubes with red rot. Those alloys are less susceptible to red rot, but not immune.

The best way to store an instrument is absolutely dry. I have seen brass instruments stored dry for 15+ years and they were in perfect condition and ready to use instantly upon removal from the case. Of course storing an instrument completely dry does take some energy. I swab my instruments several times and then do a few rounds of vacuuming to make them dry before storage.

I have also seen new instruments played for a short amount of time (thus, they have moisture in them), stored away in a case for a couple of months and they developed red rot. These particular instruments were made of a brass alloy that seems particularly susceptible to red rot. I'll refrain from mentioning brand names to protect the innocent.

Best advice on this thread!

Dry it and put a protective layer of something on raw brass, like inside of the outer tubes. To prevent rust or oxidation you oil a gun for storage. For long term storage arsenals coat them in cosmoline. I read a post once on TTF from a guy who bought a lot of old horns. He said, based on case contents, ones put up with superslick on the slides seemed to do very well and cleaned up easily.