The great cancer of trumpets is red rot. Yet, do we understand why it occurs? Think I have heard it said it is dezincifaction of brass. But what really causes it? I have only had one horn that has it, and it came to me that way. My son has used it for two years regularly- marching horn getting several hours use each day- but it has not gotten any worse. So why the severe attach with the previous owner, but no more with me. Is saliva that different person to person? Lead pipes are usually most prone to red rot. However, one would think that if saliva were the culprit it would be most prominent near the water valve, or on the third "dump" slide of horns that don't have a 3rd valve key. Many kids never remember to empty them so horns often get put up "wet.". Or maybe whatever reaction occurs immediately upon entering the pipe and becomes unreactive. Are some horns more prone to it? Thoughts or insights?