The actual reason i am asking is not only for general polishing of nickel or copper waterblocks, but also because i have corrosion damage from the previous owner that has literally eaten away the nickel plating on my auros 1080ti in a dozen areas on the block, pretty harsh. I have thought about using some fin sandpaper in the troubled areas as long as i stay away from the areas that the o-ring sits although there is damage around that area also. Then after using fine sandpaper i was considering using a metal polish. At this point after using sandpaper does it even matter if the metal polish is abrasive?
I am not talking about the bottom where it sits on the chip, i am talking about the inner blocks metal where the water flows through like a gpus actual water channels are of the block.