I have seen modern epoxy lacquer peel off, the silver plate on several horns and even some gold plated instruments with problems. The big question is NOT how do we apply even more stuff, rather how do we respond in each case. Horns in general: wipe off after EVERY USE sweaty or not. Use a microfiber cloth that absorbs more than standard natural fibers. Lacquer: as long as the surface has no scratches or other ways for your sweat to get "under" the coating, you are in good shape. This can be hard to achieve at the first and third slides. Silver is a metal that can combine with other elements like oxygen or sulphur. It is also soft. In the interest of keeping the finish shiny I do not recommend any type of polish or polishing rag. They just increase the amount of mechanical wear! Cleaning the horn regularly by putting it in very hot salt water with a big piece of aluminum foil restores the silver finish WITHOUT the abrasives found in EVERY polish! If a horn is properly gold plated, it is first copper plated, then silver and finally gold. That is the only gold finish in my experience that is durable. Still, it is soft and subject to mechanical wear so I always use an additional squirt of glass cleaner on the microfiber cloth instead of wiping it dry. Corrosion is defined here: Corrosion - Wikipedia, the free encyclopedia I guess using this definition, the oxidation/sulphurization of silver would be a form of (reversable) corrosion. When Lacquer is damaged, the brass underneath also "corrodes" as well as the moisture of our sweat getting under the lacquer and annulling the bond between it and the metal. Just keep your axe clean based on your body chemistry and the instrument will give you decades of good service.