Just thought i would ask here as well as in the thread i made today in the straight razor section, is this a coti, the light colour side is flat, but the darker side is a bit uneven through wear, though not to bad, so how do i flatten this stone on both sides, do i use the same method for flattening on both sides, and how exactly do i use this stone? the dark line is not a crack, but rins through the stone on the light side.