ozboy

I am guessing that you may have red rot in your horn or know somebody who has.
I had a calicchio and stupidly bought a second hand lead pipe from a beer drinking player (not knocking beer. I just don't drink it while I am working as I want to look after my horn).
Red rot showed up as little bubbles in the silver on the lead pipe. When you looked down the inside of the leadpipe, the surface looked pitted. I did a fair bit of research and bought a new lead pipe. I did this as I felt the pitting was affecting the air flow in the leadpipe and I didn't want the situation to deteriorate.
When I did my homework, it seemed that red rot was more prevelent in certain makes of horns. I could not ascertain if this was to do with the varying composition of the metals used in different lead pipes.
Having said that, I had a mate with a horn with redrot that is keeping it till it absolutely dies. The red rot has been in the horn for a number of years without really drastic effect.