Corrosion on newer LT Bach slide

[Mamaposaune]

Hope this link comes through. Not my horn, I was just strolling through ads and noticed this newish Bach 16, and what looks like red-rot, or some type of corrosion, on the nickle-silver outer slide. (Pics 5+6)
What gives? Even if it was not well maintained (kept clean) it does not seem as if this should happen in just a few years.

[GabrielRice]

You can see problems on the bell too. That's not corrosion, and it's certainly not red rot. It's a lacquer problem.

[Cotboneman]

I agree that does not look like red rot. What it looks like is a really poor lacquer application.

[Mamaposaune]

OK. I jumped to a conclusion there. Still, it doesn't seem like a new-ish trombone should have lacquer issues like that. Hope it's not common, although it should be covered by the warranty.

[hornbuilder]

Dezincification (red rot) does not occur in nickel silver. Looks like either a contaminant on or under the lacquer.

[tbonesullivan]

Looks like either something messed with the lacquer, or the horn was not cleaned properly before lacquer. Also depends on how it has been stored, used, etc.