Smooth v. Harsh Or is it: Dull v. Sharp? A Connundrum

[leighton]

So I've been getting a lot of razors other people send me that have been honed by other people, experimenting with different techniques, sending razors out to be tested by very experienced wetshavers to determine which honing strategy produces what.

Anyway, there seems to be a correlation between smoothness and dullness, and sharpness & harshness. What I mean is that a duller razor will feel smoother and give less razor burn. And a Sharp razor will feel harsher and leave your face feeling pretty raw if too much pressure is used. I measure the dullness by angle the blade will cut at, how it passes the HHT, and how it passes my own sharpness tests. A couple of the other SR users report the same thing. Smoother, but not as sharp.

Am I imagining things? Now, obviously, you can have a dull razor that is also harsh. Probably caused by not being shave ready. But I'm talking about razors you would shave with.

Thoughts? Have I gone off the deep end?

 

[Chicken Enchilada]

I've only been at this for 4 weeks, and have only shaved with one razor honed by one person. Given that, I believe that the perfect razor is not the sharpest razor. It isn't a dull razor either, but it is somewhere in between, tending towards the sharper end.

Also, I imagine the finishing stone is very important in this. From what I gather not all stones cut the same why, it doesn't matter if the grits are similar. So if you take two razors to the same level of sharpness, but finish on two different stones, it's possible that one can be smoother than the other. Of course I don't have any experience honing, this is just based off of all those threads I've read over at SRP.

P.S. YMMV

Everyone is different.

 

[Ray-man]

I have played around with this too. Between the finishing stone and the finish stropping I have used .5 and .25 diamond spray both in sequence and individually, and again following up with crox. In each case, the HHT was passed without problems. Shaving in each case, both for me and some tests I sent to other people, was harsh and not acceptable.

I abandoned using the diamond spray and now use only crox. I have not had an issue with harshness, nor have any of the people I have been honing for.

I also don't specifically know why this happens.

Ray

 

[leighton]

I've seen some edges which are very sharp, but who's bevel is not very polished and the edge looked like it would be "toothy." Consequently, the shave was harsh. Definitely another factor that leads to harshness, and I suspect the diamond spray leaves this "scratchy pattern" if used on certain mediums.

But thats something else.

 

[mparker762]

Harsh blades have one or more characteristics that causes them to bang up your skin, smooth blades don't. There isn't really any one thing you can point at and say "this causes harsh edges". Slightly arched edges (or multiple bevels) tend to feel smoother because they basically lower the angle of the edge by a few degrees. Rougher or coarsely honed edges feel harsher because they're unevenly sharp (see the Verhoeven paper) so you use a steeper angle or more pressure to get the duller areas to cut well, and the parts of your skin that are getting the sharp areas get peeled too deep; the same thing happens if your blade has sharpness variability at a macro level, say the toe is much sharper than the middle or vice versa. Extremely delicate edges feel harsh because the edge isn't dimensionally stable - it folds over and collapses and becomes unevenly sharp (but the bits that are still sharp are *really* sharp), though this can be mitigated by lowering the blade angle. Extremely dull blades feel harsh because they pull at the whiskers.

The last year or so I've tended to opt for smooth, moderately sharp edges with a minor degree of arching in the bevels. I occasionally go through phases where I go for the really wickedly sharp yet distressingly weak edges and just shave with the razor flat against my skin. Both give great shaves, but the former is easier to achieve and maintain hence my general preference for it.

 

[Seraphim]

I used to hone all the way to 0.5um lapping film., then chromox


I found the edges to be harsh.

Now if I have a nice edge off of the 3um, then hit the chromox, it feels just as sharp, but much more comfy.



It is interesting.....

 

[English]

First of all, the mirror edge for me is not a state that matters.

I think that sharp is when a V edged is perfectly formed. For me, I achieve that sharpness with a 10K hone. Some guys get there with a coticule, some with a Norton etc etc.,

I think that the V edge deforms very quickly and there are various mediums that will reset it.

Finishing hones, pastes, linens strop and leather strop are examples.

It just so happens that some finishing hones will polish the edge, but I think the polish makes little difference to the shave.

The thing that matters is that the edge is in full alignment, when you shave with it. After the shave, the metal needs to rest before it can be realigned.

I think it also needs to rest after a bevel setting honing session.

Comfortable shaves are had with perfectly aligned edges. I think most uncomfortable shave are because the edge is not sharp because of a metal fatigue
which can be rested and realigned. There is a point however when a new edge has to be set with a rehoning to reset the bevel .

So I think that comfortable edges are sharp aligned edges and I think the degrees of improving realignment are called smoothness.

Bottom line, sharp razors give comfortable shaves. Smoothness is just a process of making the edge sharp.

 

[Rick Sparks]

What is it that is supposed to occur when a metal blade is resting? Some realignment of its molecules? This is the first mention I've seen of a need to rest blades and I'd sure appreciate a bit more detail on what happens when a blade is resting. Cheers!

 

[The Knize]

Love topics like this. Such a chance for me to learn and "listen" to the back and forth discussions of experts on this stuff. WhaI I do not know know about hoing would fill volumes.

Let me ask a question that has been bothering me, though. I thought I had always heard that any sharp edge on a microscope level was like a saw blade with tiny rough points going back this way and that along edge and that that was what really did the cutting. That a perfectly smooth edge, I guess, would not grab hold so to speak and would not cut as well. I think this makes sense in my knife edges. A slightly rough blade seems to cut through things more easily that a truly sharp but smoother blade. Maybe not cut as neatly, but to grab hold better and power through.

So what happens with a smooth razor edge. It has to cut through a hair in the same manner anyting cuts through anything, correct? Is is possible that a microscopically slightly rougher edge grabs into a whisker more easily that a perfectly smooth one does, and those passes all of the sharpness tests, etc, but is still more irritating to the skin than a smoother edge?

 

[gugi]

Let me ask a question that has been bothering me, though. I thought I had always heard that any sharp edge on a microscope level was like a saw blade with tiny rough points going back this way and that along edge and that that was what really did the cutting.

It's a matter of magnification, no edge is sharp and straight on a molecular level. However there is a relevant lengthscale - it's set by the cuticle. Prof. Verhoeven found that pretty much all shaving edges are about 0.3u thick.
At that level of thickness of the edge teeth are good.

They can help for dull edges but that would still be very uncomfortable edge.

The popular mechanics article from the 1930s dispelled the speculation about teeth. I think the barber manual kept talking about them decades after it.


As far as I am concerned the 'resting' is another unproven speculation, and at this point I consider it a myth, or on a day I'm more cynical a fabrication.

 

[Seraphim]

It's a matter of magnification, no edge is sharp and straight on a molecular level. However there is a relevant lengthscale - it's set by the cuticle. Prof. Verhoeven found that pretty much all shaving edges are about 0.3u thick.
At that level of thickness of the edge teeth are good.

They can help for dull edges but that would still be very uncomfortable edge.

The popular mechanics article from the 1930s dispelled the speculation about teeth. I think the barber manual kept talking about them decades after it.


As far as I am concerned the 'resting' is another unproven speculation, and at this point I consider it a myth, or on a day I'm more cynical a fabrication.

Bingo.


Metal deformation is either elastic or plastic .

Elastic means that it can spring back, it does so immediately. Plastic means it has deformed more than it can spring back from. Wait 24 hours, wait 365 days, it's not going back.

Hey, barbers had to sling the bull about something back in the day

 

[leighton]

Resting is BS in my opinion. All that happens IME is that the razor rusts.

 

[The Knize]

< Prof. Verhoeven ><popular mechanics article from the 1930s >

I need to hit the books!

 

[mparker762]

Let me ask a question that has been bothering me, though. I thought I had always heard that any sharp edge on a microscope level was like a saw blade with tiny rough points going back this way and that along edge and that that was what really did the cutting. That a perfectly smooth edge, I guess, would not grab hold so to speak and would not cut as well. I think this makes sense in my knife edges. A slightly rough blade seems to cut through things more easily that a truly sharp but smoother blade. Maybe not cut as neatly, but to grab hold better and power through.

You should read the Verhoeven paper, which shows edges at up to 3,000x magnification under a scanning electron microscope (he actually examined the edges at 10,000x for purposes of measuring the edge thickness, but only shows photos at a max of 3,000x).

Basically, beyond about 2-4k grit the metal is too thin at the edge to support sawteeth - it just breaks away. So you see nice grooves running down the bevel but no teeth at the edge just a ragged edge. As an analogy, imagine furrows in a field on the edge of the ocean - you would expect the furrows to extend into the ocean in a toothlike pattern, but then once you get there you discover there's no beach just the cliffs of Dover...

So what happens with a smooth razor edge. It has to cut through a hair in the same manner anyting cuts through anything, correct? Is is possible that a microscopically slightly rougher edge grabs into a whisker more easily that a perfectly smooth one does, and those passes all of the sharpness tests, etc, but is still more irritating to the skin than a smoother edge?

That probably happens to some extent, but the hairs are 80-120 microns thick and we're talking bevels that are 0.3-0.5 microns across.

 

[gugi]

At that level of thickness of the edge teeth are good.

I have no idea what did I mean to say... I deleted a paragraph I wrote because I decided it was unnecessary, so that's probably a leftover - disregard it.

 

[chess1]

I read most of the posts and i think i should go head and say what i think about sharpness and smoothness of the blade.
I personally think Now days people uses pastes and gets sharpest edge out there.
Next you use that blade couple times and that sharpness including is gone.
if person gets proper honed razor that blade should shave smooth and edge should last at least 3-5 months.
I have never seen any edge will bent and come back right away except ones. Someone send me Razor by Name ERN
that edge was bending and coming back front of my eyes. i was using 100x microscope.
Some blades will not take sharpest edge .There is no way you can put edge to that Blade some will do.
I have razor by name Jaguar -This is the sharpest edge taking Blade i have seen so far.
Lastly i think This is the most important fact.
if you are honing the blade don't try to get sharpest edge ,GET that blade honed properly . Properly honed blade will make you very happy in long run or your customers.
They won't be sharpest but will be the smoothest.
Dull Blade will never shave smooth. Dull blade will pull etc.

I am against using any kind a pastes including chro2 if you use more then 20 laps.Even chro2 will make your edge fragile.

1 more i think 95 % straight razor users doesn't use straight right. Pushing down blade on your face isn't right way to shave.
hope this helps.

 

[mparker762]

< Prof. Verhoeven ><popular mechanics article from the 1930s >

I need to hit the books!

Here's the popular mechanics article mentioned earlier. It's easier sledding than the Verhoeven article, but the photos are 3000x optical photos, and aren't quite as stunning (though they are consistent with Verhoeven's SEM shots).


Also, this article from the Schick website has some interesting tidbits.

 

[Seraphim]

LeGrelot made those Jaguar razors, if I'm not mistaken.

 

[Sticky]

Another link to a few interesting, comparative pics at different magnifications: http://blog.modernmechanix.com/2006...ving&Qif=shaving_0.jpg&Qiv=thumbs&Qis=XL#qdig

 

[The Knize]

Thanks for the links I should have know about and looked at these a long time ago.