Some times that plating is beyond polishing. I have soaked it in evap o rust or vinegar or citric acid over night. Then I took a green scrubby bad and got the plating off and made sure the rest of it was nice and dry. Then I polished up the bare metal Some times that plating doesn't want to come off so it gets soaked again in one of the other choices - it seems like once it flakes it is pretty simple to get it off. Some times Dawn takes off enough grime that all you have to do is polish it up just don't let it air dry.