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I've just noticed a problem with red rot on my 1963 Conn 25J. Were these horns prone to it? Is there much I can do to stop its spread?

'Red rot' is a term to describe the reddish spots left behind after the zinc has precipitated out of yellow brass... leaving behind porous copper. It starts on the inside and by the time you see it, the damage is done. You can prevent it somewhat by keeping the inside of the horn clean and free of acidic food particles and saliva. All yellow brass horns are prone to develop the condition and I know of no particular brand or model of horns that are more susceptible to it. You're going to see it appear most commonly in leadpipes, main tuning slides, in trombone slide crooks, and sometimes even in the valve circuits. On brass and lacquered finishes, it will appear as reddish spots about 1/16" in diameter that sometimes have a dark center. On silver plated instruments it might appear as a small bubble in the silver finish. I'll venture a guess that ALL yellow brass horns have some degree of 'red rot'. It just isn't noticable until it finally comes all the way through the brass.

so once it is visible can it get worse or does it just stay like it is? and is there anyway of getting rid of it? Thank you.

josh wagner wrote:so once it is visible can it get worse or does it just stay like it is? and is there anyway of getting rid of it? Thank you.

It will get worse. You may be able to slow the progress by keeping the horn clean but the only way to fully correct the condition is to replace the part.

BTW.... don't confuse the tarnish spots that appear on a lacquered horn when the surface has been dinged and the lacquer knocked off with 'red rot'. The latter condition is only on the outside of the horn and likely won't penetrate through to the inside.

Thank you.

Don't worry about it until you have a leak, then patch it.

What the rest of the guys said. Another way to describe it is after the zinc dissipates, it leaves behind a "sponge" or a "swiss cheese" copper that lacks the structural integrity provided by the zinc, which is the primary reason the zinc is alloyed together with the copper in the first place.

TubaTinker wrote:'...All yellow brass horns are prone to develop the condition...'

How does this effect Gold Brass or Rose Brass instruments?

josh wagner wrote:so once it is visible can it get worse or does it just stay like it is? and is there anyway of getting rid of it? Thank you.

There is no cure for red rot- YET! But if we all can dig just a little deeper and donate to the Red Rot Foundation, we can work towards the goal of ending the scourge of red rot in our lifetime. Operators are standing by.