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

Originally Posted by treydampier

Since there are many experienced members here, I have a question. Does the grind of the blade effect the impact of the shave in the context of sharpness? The reason I ask is that I feel like the full hollow is the easiest grind to use and hone, but I feel like the wedges really do better than one pass than the full hollow. I am sure its probably the honing, but I use a 12K on each and finish CrOx paste. They all easily pass the HHT and shave test, but I was just wandering if the grind effecting the feel of the edge is related to this topic.

I think so Trey, look back at posts 11-14

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 .

We are saying the exact same thing, the difference is in the amount of steel removed after 4k... Some of you think that there is still quite a bit being removed... Myself and others think that there is very very very little being removed...

The > is not getting much thinner after 4k it is getting smoother

I kind of wish we had a scanning electron microscope at our disposal and an SRP research facility to end our speculations. Obviously the Verhoeven paper does not address the perceived comfort of an edge which I care about as much if not more so than "sharpness" or "keenness".

Honestly I love speculating about this stuff and theorizing as much as the next guy, but it can also get frustrating for me; like chasing your own tail.

I love the fact that the Verhoeven paper is there for us. I'm bummed that it leaves off where we need it or something like it to pick up. Perceived comfort based on various edges, abrasives used and subjective opinions in actual shaving. That's why I think for our specific purposes, the Verhoeven paper is only partially conclusive to what interests us.

Chris L

Originally Posted by mparker762

I hate arguments by authority, but the commercial razor blade manufacturers disagree with you. The friction i'm talking about isn't the friction between the whisker and blade after the whisker has been severed - its the friction between the whisker and blade while it's still being cut, as the blade is forcing the whisker apart. The initial effort to separate the strands of fibrin is determined by the edge width, but the whisker is as much as 180 microns across, so the two halves of the whisker are riding up the bevel quite a ways, and the whisker in front of the cutting edge is being stretched as the blade is forcing the two halves apart, acting like a spring and pulling the two halves tightly against those bevels. This can cause substantial friction, and substantial resistance.

A fair explanation
I don't know enough about this topic, so I'll accept your point.

Originally Posted by mparker762

Of course we can. The edge doesn't get any sharper past about 4k (...)

That goes against all my observations and against all logic.
Why would an edge be continuously be able to be defined between thiner boundaries, as we progress through increasingly finer hones, and certainly stop doing that at the 4K level?
If it were true, this would mean I could hone an razor till it peaks at my Chosera 5K (I'm sorry it's not 4K) and next, just suffice to replace the Chosera scratch pattern on a Coticule with water (that's how I eventually finish the vast majority of my edges), and end up with a result that meets my standards? I have to ask you to take my word for it, but that razor would not be sharp enough to my standards.

Talking about Verhoeven: I scanned through his paper once more. Where does he state that the edge width (EW) stops decreasing at 4000 grit?
Verhoeven reports about how the edge width decreases from stropping on CrO or on 1µ diamond paste. "The 1 micron diamond abrasive produced optimum edge widths of around 0.3 microns, while the CrO abrasive gave only slightly larger EW values, around 0.4 microns."
Maybe those guys saying that diamond paste is "harsher" than CrO, are talking about too keen edges after all.

If the differences are that significant on paste particles of 1µm and 0.5µm, then I don't believe that they will only be in the nanometer region on hones that use abrasives coarser than that.

Bart.

In my little mind, the edge off of a coticule or norton 8k is sharp it gives me a little feed back. If I polish that edge on some finer abrasive it glides through the hair like a "wonderful whisker wiper", in my mind it is a little sharper.

That is the way that I see it. So much for semantics.



I like to keep things simple, --- like me.



This ends my foray into the dogma of sharpening.



Charlie

Originally Posted by gssixgun

We are saying the exact same thing, the difference is in the amount of steel removed after 4k... Some of you think that there is still quite a bit being removed... Myself and others think that there is very very very little being removed...

That is true. Only, the tools to remove it become also increasingly slower. Hence the need to not switch over too soon. But in the end, you can't paint a fine line with a thick brush.

All in my humblest of opinions, of course.

You did realize I hope, when you started this thread, that we would probably not become one step closer to a unified theory on these matters?

Bart.

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.

Originally Posted by Bart

A fair explanation
I don't know enough about this topic, so I'll accept your point.

That goes against all my observations and against all logic.
Why would an edge be continuously be able to be defined between thiner boundaries, as we progress through increasingly finer hones, and certainly stop doing that at the 4K level?
If it were true, this would mean I could hone an razor till it peaks at my Chosera 5K (I'm sorry it's not 4K) and next, just suffice to replace the Chosera scratch pattern on a Coticule with water (that's how I eventually finish the vast majority of my edges), and end up with a result that meets my standards? I have to ask you to take my word for it, but that razor would not be sharp enough to my standards.

Or take that chosera 5k edge and spray it with teflon, which is what the big boys do.

Originally Posted by Bart

Talking about Verhoeven: I scanned through his paper once more. Where does he state that the edge width (EW) stops decreasing at 4000 grit?

He doesn't, at least not directly. But he measures an edge from some coarse grit diamond (9 micron?) and it's 0.4 or something, and then later measures with 1 micron and it's 0.38 or so, and later with 0.5 micron chrome oxide and it's 0.37 or .36 or so.

Originally Posted by Bart

Verhoeven reports about how the edge width decreases from stropping on CrO or on 1µ diamond paste. "The 1 micron diamond abrasive produced optimum edge widths of around 0.3 microns, while the CrO abrasive gave only slightly larger EW values, around 0.4 microns."
Maybe those guys saying that diamond paste is "harsher" than CrO, are talking about too keen edges after all.

If the differences are that significant on paste particles of 1µm and 0.5µm, then I don't believe that they will only be in the nanometer region on hones that use abrasives coarser than that.

Hmm, now I've got to go back to verhoeven's paper, because I distinctly remember them topping out at 0.34-0.38 past about 9 micron diamond, depending on the hardness of the steel and irrespective of grit.

Originally Posted by gssixgun

Question???

Is there anyone who thinks there is more then say 2/100 of a micron between sharp and too sharp????

I think the only way you will ever get an answer to that Q is if you put a numerical definition on where "too sharp" begins, and after doing so, you could say there is 1/1x10^1000 of a micron difference between sharp and too sharp...if ya wanna get technical about it

Originally Posted by mparker762

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).

.

This is True if you are talking about in curtain grit.
Example .
if you use 4 k and edge will get the level 4k can get . after that edge will not longer get sharper if you still using 4k
I agree
But we switch to 8 k and continue to hone edge will get thinner.
This is important understand.

i think what they made experiment was knifes etc.
how they sharpen knifes ? they will never get edge so thin which we get on straight razor.
that knifes edge will broke down after 1 potato cut right?
This is what they doing . they are getting edge on level of 4 k and stop in there . then they start to polishing . by polishing they get a little more sharpness that is it.
i check edge after 4k and 8k and after coticule ,escher.
as i go up edge gets thinner and cuts better .