I would hazard a guess that the friction of mylar belt is polishing the brass, therefore, leaving a slight residue. This is not a bad sign as the smoother the brass surface becomes, the better
molecular adhesion.
Brass Pulley for My TT
I recently had a machine shop make a Brass pulley for me to try, it is working great but; I am seeing some yellowish dust which I assume is brass. Is this normal? I don't have much knowledge of Brass so I am looking for answers??? Will this stop after a while or not? The belt is made of Mylar.. I have cleaned it off a couple times but it is still producing it...