Thread: What Does it Mean, Taking an Edge too Far?

Originally Posted by DaveW

(i still would like to see actual SEM pictures of the *edge* of the razor, and not the bevel - before and after stropping. Are there any of those?)

Verhoven http://www.google.com/url?sa=t&rct=j...dOblj9NWadTmUw
has SEM photos of .5 micron edges.

You will be disappointed. He didn't observe the effects of stropping. Glen did some stropping tests a while back indicating that overworking the edge at higher grits (as in pasted strops) wasn't a practical consideration.

I have intentionally worked edges with a barber hone til it was apparent at 45x the edge had broken down. It was "overworked". The edges went from straight and even and sturdy enough to cut without apparent damage to feathered and burred which would break while cutting and result in course torn steel.

IMHO those times we have a edge which seems harsh the culprit is very tiny "teeth" from the scratches which sub-microscopically run all the way to the edge and protrude. Our face can feel them but they are too small for even the SEM to view. Burnishing(or actually pressure flowing them) by stropping smoothes those tiny points back to the straight of the edge. At such a granularity which must be significantly sub .5 microns the steel actually is formed by pressure and heat from the leather. At this small scale steel isn't behaving like we observe it to at 45x. Your own skin burnishes the razor. Leather is tougher and doesn't complain.

Recently someone was testing a honing job I did. One comment was "harsh" so they stropped the blade. Further stropping beyond what I had done took the razor from sharp but harsh to simply smooth. Often users comment about Feather blades being too sharp or harsh until they are shaved a couple of times........burnished from use. Here is where YMMV or personal preference comes into play. Someone with finer sensory ability (denser nerve endings?) would feel the "teeth" more acutely.

Finally consider what has been published about DE blades. They are honed to 1K or less and then subjected to machine burnishing and coatings.

The situation of a razor losing sharpness part way through a shave might be nothing more than a underdeveloped honed edge which is cutting by virtue of some "teeth" which are extending past the edge which hasn't yet been properly developed by getting both planes to meet evenly. The shave-ability of such an edge quickly disappears as those teeth are burnished back to the edge which hasn't yet been properly formed .

All this indicates to me the knife sharp term of "wire edge" or burred edge(the often recommended treatment is drawing the blade through some material to tear off the burr) isn't a term which accurately describes what happens when we get above 4k-8k grit level.

I don't believe at .5 microns and below there is any steel which is going to survive much flexing back and forth against skin or leather. It would seem to me stropping works because at these sub-visual levels the steel is being formed into a smoother boundary which slides more easily across the nerve fibers on our face whereas the unstropped edge has the capacity to rake across these nerves and cause discomfort. Both of these conditions result in sharpness which for a knife would be superior but when applied to the sensitive skin on your throat are very different indeed.