You only need to flatten the first inch of the back next to the cutting edge. After fifty years of use if you have shortened the chisel from sharpening you can flatten the next inch.:smile:Thanks for the tips. I did swipe the back of the chisels a few times. The back of the chisels are weird now that I ran them across the stones. They are almost smudged in some areas on the back more so towards the tip, and the rest of the blade seems untouched by the stone. Same thing on the bevel end, there is a small shiny area and a dark smudgy area.