Oh dear. Dick says that reeds can be made of all those various things, and he is often wrong, as ever (I've never come across aluminium reeds, and as for plastic ones...be serious, Dick!) He utterly fails to mention that, after brass (which does not rust), the next most common harmonica reed material is phosphor-bronze (which does not rust). Certainly, there have been some experiments with stainless steel (which does not rust). Contrary to what Dick says, harmonica reeds are never, ever made of "steel." Which does rust, of course, which is why "steel" is not used. Stainless steel is a whole nother thang, Dick. I might suggest that, in discussing this matter, we keep our feet on the ground and address things in a real-world, practical manner. Listening to Dick, you'd think he'd never actually seen a harmonica (I won't be unkind enough at this juncture to suggest that his playing, as we know it, suggests a very limited transaction therewith).