Hi I`VE Been playing trumpet for two years and I`m in the seventh graded and my trumpet keeps on getting this greenish stuff on my valves and it won`t wash away and I`ve gottin it professionaly cleaned once and it keeps on coming back and my band teacher said it will start rusting soon any tips so I don`t have to keep on bringing it back their?

Here`s a tip: do you dry off your valves after each playing session? And do you oil your valves before each playing session? Those may be contributing factors. This green stuff you`re talking about is a result of the acid in your saliva (yes, your saliva is a weak acid) reacting with the metal of the valves. Take chemistry in high school, it`s useful!

Thomas