Synopsis: A sharp-cutting plane blade or chisel depends upon the meeting between two flat, polished surfaces. That’s why you need to pay as much attention to the backs of your blades and chisels as you do to the bevels. A flat, smooth, polished back—as clear and reflective as a mirror—is the goal. Chris Gochnour shows you how to achieve it using sandpaper and a flat surface.

You surely have heard it before: A sharp cutting edge is the meeting of two flat, polished surfaces. That’s why you need to give as much attention to the back of a plane blade or chisel as you do to its bevel.

You must first flatten and smooth it, and then polish it to remove all the scratches. when you’re done, it should be as clear and reflective as a mirror.

I wouldn’t be surprised if the prospect of…