I do not have this case in any of my saxes but while browsing on ebay I saw a handful of vintage and not-so-vintage saxes with brown-reddish tinges on the surface. All my searches showed how it eats the brass alloy (w/ zinc) and there is no way to stop it once it begins eating up on the brass. Looks like those guys either neglect or do not know how to take care of their instruments. I didn't know what it is until I further made web searches. Gordon, your comments, suggestions, please. Or anyone? :?