Quote Originally Posted by David Barnett View Post
Flattening on sandpaper, if you're careful to avoid buckling and pay attention to technique, is totally fine for both planes and chisels. I'd still prefer to do the final laps on a fixed diamond stone—not the entire back, though—just near the edge.
Yeah, me too on finishing the back with something more firm. The PSA roll paper (I've been getting mirka gold for about 5 or 6 years, or whatever they've branded their premium al-ox) is forgiving because you can lap on it like a stone and it has enough adhesive that it will never buckle. Same with 3x if there's enough goop under it to make sure absolutely none of it moves.

But the stone is still more precise and a more logical next step after 100 or 200 grit sandpaper (or more preferably, 100 grit sandpaper that has been worn to the latter in use).