So I finally purchased my gold filled metal from Rio Grande, double clad, 14/20- and i finished a piece, which was a charm on a necklace, and once again i got that brassy dark color on part of the piece after it was worn a couple times. Has anyone ever finished their gold filled in a matte finish, where it stayed the same color, if so tell me your secret?? I find when I finish it in the glossy finish- it does not happen, but i want it matte!