External red rot

johnfin · Regular Member Joined: 17 Mar 2011 Posts: 48

I have external red rot. After removing it can i touch it up with a lacquer product.

Mike Prestage · Posted: Wed Nov 06, 2019 6:25 am Post subject:

Unnecessarily negative response now edited:

In principal yes, but it will come down to how skilled you are in whichever application method you chose, and how happy you will be with a less than perfect result vs. just having an area of missing lacquer. You'll also want to think about making sure you choose a lacquer that will adhere well to brass, and that you get the surface clean enough to minimise adhesion issues. (This should be much easier with a localised touch up than a whole horn.) Your chances of getting it to look good will be much better if it's on a smallish part of the horn so that you can remove all the lacquer up to soldered joints all around and then relacquer a discrete section.

Further to Brad's comment, are you sure it is external? You certainly can get reddish surface corrosion on the outside of horns but this looks very different to what people usually mean by the term red rot.

Mike

Brad361 · Posted: Wed Nov 06, 2019 6:34 am Post subject:

As far as I know, red rot is caused by acids in human saliva causing the zinc content in brass to leech out, I don’t believe this is an external process. And it can be delayed by keeping the horn internally clean, but the only way to “remove” it is to replace the affected part.

Brad
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HaveTrumpetWillTravel · Posted: Wed Nov 06, 2019 6:41 am Post subject:

Can you post pictures? I actually have a similar horn, where it is showing red rot, corrosion, rusting, or acid bleed in several sections (bell, main tuning slide, third slide, leadpipe).

A lot of the posts about red rot assert it's rare to get outside of leadpipe and tuning slide, or that it may not be red rot but some other corrosion, but to me what's on mine sure looks like red rot too.

I'm also curious what beside cleaning can arrest the process. Is it worth nail polishing over little corrosion spots? Oiling them? For corrosion that shows but isn't necessarily red rot is there any better treatment?

multiphonic · Veteran Member Joined: 14 Oct 2019 Posts: 139

Are you sure it's red rot?

https://www.brassandwoodwind.com.au/red-rot/

If so, not much to be done except replace parts. It can't be buffed away as it's not 'external' (i.e., only on the exterior/visible surface). It's a change in metal structure due to dezincification. The remaining (mostly copper) structure is fragile, will eventually lose integrity and fail.

If it's acid bleed, the surface can be prepped and relacquered.

You may want to take it to a competent technician for a proper evaluation.

One can play a horn afflicted with red rot for years. My daily player has significant rot on the leadpipe and still plays well. One day it won't. There is nothing to be done about it.

HaveTrumpetWillTravel · Posted: Wed Nov 06, 2019 7:18 am Post subject:

Thanks for the website--my trumpet that I think has red rot I bought 2nd hand on the cheap. It is all yellow brass, which seems more susceptible and the red rot doesn't seem advanced. I do wonder in my case if it's not several things at once (for instance one tuning slide and a spot on the bell have the telltale pink, but there's a rusty looking spot on the third slide that might be a brace using a metal prone to rust and there are dark spots by other braces). I'm keeping it cleaned and oiling regularly.

So here's a related question: it sounds like all red rot is corrosion, but is all corrosion (on brass instruments) red rot?

OP, where is the red rot on your trumpet?

johnfin · Regular Member Joined: 17 Mar 2011 Posts: 48

HaveTrumpetWillTravel · Posted: Wed Nov 06, 2019 7:25 pm Post subject:

That sure looks like red rot. The good news is a tuning slide is probably the easiest part to replace you could think of. Mine had two tuning slides and I just switched over to the more square one (which I like as much or better as the rounded one).

HERMOKIWI · Heavyweight Member Joined: 24 Dec 2008 Posts: 2581

It looks like red rot to me. Unless it's worked a hole all the way through (so it's leaking air) it isn't usually going to create a significant problem in playing characteristics. It can take a very long time (even decades) for a hole/leak to develop and, of course, testing this in a tuning slide is very easy.

I don't interpret red rot as "corrosion." To me, it's more in the nature of "erosion." Technically, it's the dezincification of brass. It looks "red" because it accentuates the copper in the alloy by color contrast. In most instances it's just a cosmetic issue. However, if a hole/leakage appears you have a big problem.

Some makes/models of horns are very susceptible to red rot. I've replaced the lead pipe of my 1966 Burbank Benge 3X (purchased new) probably 5 times at least. It's a very annoying problem. None of the replacements was due to a hole/leak. These were all cosmetic issues I wanted to resolve when re-plating the horn in silver plate.

I go through silver plate very quickly so I finally gave up and had the horn gold plated. Of course, this didn't affect the susceptibility of the leadpipe to red rot. I recently replaced the leadpipe again. I'm committed to not playing the horn in the future to preserve it's cosmetics. My plan is to donate it to the Nebraska Jazz Orchestra as a part of its history (I founded the Nebraska Jazz Orchestra in 1975). For that purpose I want it to be as pristine as it can be. The Nebraska Jazz Orchestra is my artistic legacy so I want to continue to be supportive even after I'm in the big band in the sky (I'll be setting up an endowment, too). These things bring great joy to life and should be perpetuated for future generations.
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Irving · Heavyweight Member Joined: 11 Feb 2003 Posts: 1887

Check to see if leadpipe has red rot as well.

Throw out tuning slide.

Replace leadpipe if necessary.

Swab new leadpipe and tuning slide after every use. Your new parts will stay red rot free if you do this.

multiphonic · Veteran Member Joined: 14 Oct 2019 Posts: 139

Definitely red rot. Really no need to replace parts until one of the afflicted sections actually fails. This could take many years and you may move on to a different horn before then. It's not an emergency.

yourbrass · Posted: Thu Nov 07, 2019 8:20 am Post subject:

The posters saying it's from the inside -out are right. Looks like a YTR2320 or something like it? The tuning crooks often do this over time, and this model was discontinued in 1994, so it's got some miles on it.

You could have it acid-cleaned to remove the scale from inside, and that's about all. The outside will stay the way it is. Nothing to worry about.
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multiphonic · Veteran Member Joined: 14 Oct 2019 Posts: 139

Speaking of dezincification...

My other hobby is live steam model railroading, which involves brass boilers, tubing and fittings. Boiler water quality is a big topic of discussion among the live steam community. The conventional wisdom is to avoid deionized (i.e., analytical lab quality) water since it is a strong enough acid to remove zinc from brass alloys over time. In theory, this could potentially result in boiler failure which would endanger the operator. Reports of actual damage from this phenomenon are very few and far between. Distilled water can be anything from deionized to steam distilled water, so it's also suspect. Many use the 'distilled' water sold in grocery stores, but some won't touch it. I used it until a few months ago.

One hobbyist, a scientist with access to good microscopic equipment, analyzed different water types for impacts on brass. Filtered rainwater and dehumidifier water caused the fewest surface changes to samples over time. I now collect and use dehumidifier water. So far, so good. Time will tell...

FWIW.