Hand Tools Archive

Re: Alloy and finishable surface

david weaver
Actually, the wire edge and whether or not it's there is a good point.

On this test, I run a clean finger over the end of the blade to remove any last little bits that are there, and then I have to wipe the iron briskly on my shirt (so it's getting a very light stropping), put it under the scope, and then often do it again. It's not getting done with significant pressure, but I think the wire edge is gone.

It is extremely noticeable if significant work is done on the 1200 stone, even though that stone is fine cutting, but careful work on the 1 micron diamond weakens it and makes 99% of it depart. if there is any remaining amount, you can actually see it, but you must take the iron and flash the edge across some light source (toward a window is fine), the same as you would have to do to see wear on an edge.

I have avoided taking a picture of the typical defects (I think they are rather the product of particles coming out, and not the product of the wire edge - though leaving bits of wire edge on wouldn't have helped) for the most part because I don't want people to get the sense that they represent the bulk of the edge. I will, though, take pictures of a couple of the edges to show what minor defects look like. I don't think the phone camera will be willing to cooperate on wood, but I may be able to create them on a flat surface and get such an amount of wood filling the viewable area that the camera can't try to ignore them. Phone cameras seem to be software-made to immediately focus away from surfaces with a shine. I can see the shiny surface for only a split second and then the software focuses on something else in the background before the picture is taken.

It may be worthwhile to take one of the irons after this is done and make it flaw free again and then actually see what stroke the small lines show up on. I check the edges before starting with the microscope scrolling across the entire edge to ensure there are no deep scratches left anywhere (those will become edge failure even if they don't leave a mark right away) and to ensure that there are no deflections or bent looking edges (which probably aren't bent, but are some lack of uniformity).

So, it's not a wire edge issue. The other thing that makes me think it's not is that no matter what, even after green chrome ox, I have never been able to get A2 to keep uniformity over a significant period of edge life. Same with the (probably) M2 irons that come in mujingfang tools. Both the LN and the muji blades are such fine pieces of gear that it's a shame that they can't be forced to act exactly like carbon steel.

Other far less refined irons have included the ones that come in primus planes (if tracks were breadcrumbs, nobody would ever get lost using one of those) and even worse, the hard to sharpen irons that came with shepherd planes - those released larger defects than typical, and early.

What I can do is get a picture of the wire edge as it's left after a 1 micron diamond without alternating or stopping. It'll be an oily picture, but you'll be able to see it.

The little things that I do with a clear finger and then with a clean shirt are maybe things the average new user wouldn't perceive or know to do anything about, but selling sharpened razors has made me very wary of what's on the edge and how gentle you have to be to get rid of it. The bar is higher there because even O1 has too much of a wire edge holding tendency to make a good razor. A good razor must tolerate linen and leather, and after holding the wire edge, O1 fails to stand up to the process that's designed to remove it and keep it away.

Which may beg the question, if I can just get the wire edge off with a clean finger and a shirt, why is it such a big deal? the answer, I think, is two fold:
1) the tsune iron just makes it unavailable to even worry about very early on (that's nice, and I think more about hardness than alloy)
2) what happens when we step down from 1 micron diamonds to something less refined. then, at that point, all irons have a wire edge to deal with, and it could be tenacious. Certain things like slurried japanese stones do well to limit the formation of a wire edge, but that takes user touch to understand. It's not practical for me to convey.

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