When you look at the razor one side is convex and the other is concave. The concave side gets the additional honing. recommended hone for the Tosuke is a 12K. The secret to honing a japanese razor is that you have to use considerable downward pressure while honing. Totally opposite to honing the usual razor. The art and skill is in knowing how much pressure to use. Too little and you'll hone for a month of sundays and too much and you can ruin the edge. You just have to experiment.