Posted by Jacob Hoffman on January 20, 2000 at 18:52:28:
In Reply to: Those irritating "scratchies" on slides? posted by John Swensen on January 20, 2000 at 16:22:30:
It sounds to me like you're experiencing a common problem with older horns. On laquered horns it is very noticable as little spots of red prominent on the lead pipe and tuning slide. This "red rot" is caused by the chemical reaction of saliva and food particals and the brass. The technical term is "dezincification." In the chemical reaction the zinc in the brass seperates leaving just the copper behind. Although there may not be visible red spots in your case, I theorize that the inside of the outer slides has red rot. The way to prevent red rot is to have the horn chemically cleaned at least once a year if not more. Although etch-clenz and other such mild acid chemicals for chem cleans will prevent red rot, the only way to actually stop a current case of red rot is to have th horn bright-dipped. Bright dip is a very strong acid that cleans the horn by removing a very small layer of brass. It eats away the copper more quickly than the zinc, so the horn has more of a yellow tint after the dip. If the horn truly has red rot, untreated it will eventually leak, and the tubes will break down.