Yuki Hallowell

Pencil grid trick if you do not already use it: scribble a grid across the face before lapping, then lap until every line is gone. It shows you where the low spots are and stops you over-flattening one end.

Did three mortises at 35 last night with no bright line at all. Slightly more effort per blow, entirely worth it.

How do you tell the difference between a wire edge and a properly sharp edge without a microscope?

Agreed, though a properly deburred edge should still slice a tomato afterwards. Both things are true here.

Almost certainly an unremoved burr. Shaving arm hair is not proof of a good edge — a thin flap of deformed steel shaves beautifully right up until it tears off, which takes about one onion.

Test for it: run the pad of your thumb from the spine down over the edge, both sides. If one side feels smooth and the other has a faint drag, there is a wire edge still on it. Remove it with very light alternating strokes on the 3000, dropping to roughly the weight of the knife by the end, then 15 passes on plain leather or even the back of an old belt. The edge will feel slightly less aggressive on arm hair and last ten times longer.

Same realisation for me. The 6000 is not a sharpening stone in the way the 1000 is, it is a polishing stage.

Diamond plate for this job. Three reasons: it stays flat, so you are not stopping every few minutes to flatten a stone that is dishing under heavy pressure; it cuts hardened steel fast with no soaking and less mess; and once the reprofiling is done it becomes your flattener for the 1000 and 5000, which is a purchase you will make eventually anyway.

Get something around 300-400 grit. Coarser than that on a kitchen knife just makes deeper scratches for the 1000 to chase.