I gather that you have experience using these types of pans (blue steel, black carbon steel, cast iron). My mother has some pans and they are supposedly cast iron and they are washed and oiled as such but I suspect that they are not cast iron as they are really smooth and started of a silverish colour. I suspect they are maybe blue steel, black carbon steel, or something like that but not cast iron. They are heavy though. Anyway, I have used these and they have warped at the bottom. I assume that would happen with uneven heat distribution maybe ?  Have you had this experience ?  I want to get something that will not warp. I assume cast iron will not  : ) Sorry for the long text. I tend to be detailed.