Just moved into this house. The coating on the sink is coming off. I think maybe the sink has been painted, but I am not sure. It is particularly bad around the drain where a larger piece has chopped away and it is lifting all around it. In other places there are small chips. The bottom of the basin looks worn and permanently dirty. Does anyone have any ideas about what the coating is or what could be done to fix it and/or make it look better and last longer?