Thread: My razor is too sharp???? I like a duller edge??

Originally Posted by hi_bud_gl

Now i am getting whole confused.
will you please explain what you mean by Polishing?
in my opinon BEVEL has nothing do to with sharpness of the blade. Edge does .edge touches to the cutting surface not bevel.
Polishing removes the metal right? as doing so it narrows the edge. makes them come to more close to 'V' shape. and this will increase sharpness.
May be that person was making experiment of chizels axes, knifes etc .
that is different . you don't have to get v edge on them as you know it will get so fragile and useless .

The edge gets thinner and thinner until it gets to a certain point, then it just crumbles away, and continued honing just removes metal but the edge doesn't get any thinner. This seems to happen at around the 4k mark (obviously this is an approximation because different "grits" are different and act differently - the point is that this happens at a very coarse level, much lower than we would have thought).

Verhoeven looked at commercial razor blades, a straight razor that was honed by an active straight razor shaver, and blades he honed himself using a honing jig and a variety of stones and pastes.

The thickness of the cutting edge of teh gillette blade was the exact same thickness as the edge of the straight razor, which was the same thickness as the edge of the blades he honed using the 4000 grit hone, which was the same thickness as the blades he honed on his 8000 grit hone, which was the same thickness as the blades he honed on 1 micron diamond, which was the same thickness as the blades he honed on 0.5 micron chrome oxide. And the same for blades honed by Alfred Pendray, a noted knifemaker that was assisting him with this study.

The blades were obviously getting sharper, yet the cutting edge wasn't getting thinner. So the question then is what is making them sharper? Because clearly *something* is making them sharper. One thing we can clearly see in his electron micrographs he goes up to finer and finer abrasives is the bevel gets smoother and smoother. But is this significant? What mechanism can we think of that might describe how the bevel's smoothness could improve sharpness?

The commercial razor blade manufacturers have run into this same problem. They needed to improve the sharpness of their blades, but they also need to produce them as cheaply and quickly as possible. Saving even a penny per blade makes them millions of dollars. What they have universally settled on is to stop honing at a pretty coarse level, then bake in some teflon to the edge. This improves sharpness, but how? The blade isn't thinner after this, actually it's a bit thicker. So why is the blade sharper? Because it unquestionably is sharper, at least going by the sensation you get when shaving. So what does it do that we perceive as sharpness?

What the commercial guys claim is that the teflon reduces the friction between the bevel and the whisker as it's being forced open, that the tugging sensation you get from shaving is coming from two different actions: forcing the blade into the fibrin in the whisker, and forcing the two halves of the whisker apart in that 120 micron span after the blade bites into the whisker but before it has come out the other side and the whisker finally floating free in the lather.

This also provides a possible mechanism for how a more polished, smoother bevel could improve the sharpness of the blade. As with the teflon, it reduces the friction between the bevel and whisker as it's being forced open. The commercial guys just find it cheaper and faster to do this by spraying on teflon than painstakingly polishing the bevel.

It's interesting that the knife guys that were testing edge sharpness (before verhoeven showed how to do this with an electron microscope) repeatedly stressed using materials with "minimal wedging and frictional forces", because if what you're trying to measure is the size of the cutting edge then that friction of splitting the material apart is very significant. But for us measuring sharpness by shaving don't have the luxury of choosing our testing material - we're stuck with whiskers which have the tensile strength of copper.