Hair shaving sharp?

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XiaolongJackson

Joined
Jun 5, 2012
Messages
790
Just curious: what exactly do the people here mean when they say "hair shaving sharp"? My DMT Magna Guide Quad Kit came in last week and I started freehand sharpening my knives with it when I found that the guided system was too cumbersome for me. Just a few minutes ago, I got my Delica sharp enough to cut off some of my hairs as the edge went across my arm, but not completely cleanly like a razor, and I'm feeling pretty proud of myself for improving this much in a week, but I'm not sure if I got it to the "hair shaving sharp" that the folks here talk about. So is this it or do I have more to improve on before I truly get there?
 
I can't speak for others, but when I think of shaving sharp, I think of shaving a clean patch with one stroke. This particular sharpness test is kind of subjective, though, because people have different textures to their arm hair (assuming that's what you're shaving). I use phone book paper, personally, and determine an edge's sharpness by whether I can push cut a section of it cleanly without having to hold it. I fold over about 1/4" of the edge so it stands up. Then I set the page down and try to push down through the folded edge to get a clean cut without bending the folded edge. If I can do that without having to hold the edge up, then I'm satisfied with my work and the knife is ready to use.
 
I think like dalefuller for hair shaving sharp. Then I think there is a hair popping sharp where the hair pops of your arm when the edge makes contact with it. Next in my opinion would be hair whittling sharp where you split the hair length wise and it still is attached. I use newspaper to check the knives that I sharpen for customers. Most I give a polished toothy edge for their needs on a belt grinder. So many degrees of sharpness mentioned in this forum.
 
It's really hard to define "sharp" in general, but when I use the term "Hair shaving sharp", I generally infer that it will remove a patch of armhair cleanly with a single pass and minimal pressure. A refinement of that is "hair popping sharp" where in addition to cleanly removing the hair, the hair jumps away from the cut area instead of remaining piled up on the blade. Beyond that, I usually start referring to the Hanging Hair test, as quantified here.
 
Since I don't really care for walking around with shaved patches on my arms (or legs), I just check if the edge grabs the hairs above the skin (kind of like the motion you'd use for shaving, but much slower and without touching the skin and you stop as soon as the edge catches the hair). If it does that, it would've shaved too. I mostly use newsprint when test cutting.
 
It seems that I still need to improve then. Is it possible to get to hair shaving sharp with a 3 micron/8000 grit diamond stone or do I need to strop? What process do you all go through to get your knives that sharp?
 
Simple "shaving" sharp can be achieved FAR below 8K. On my EdgePro and WEPS, I can achieve a shaving edge at very early grits, in the 180 grit / 70-micron range. Make sure you are apexing your edge fully, and watch the burrs. I would suspect that you have a rolled-over burr if you're not able to shave with a fully-apexed edge above 50 microns or so. :)
 
XiaolongJackson said:
It seems that I still need to improve then. Is it possible to get to hair shaving sharp with a 3 micron/8000 grit diamond stone or do I need to strop? What process do you all go through to get your knives that sharp?
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I think I am in the same situation as you. From what I have read of the forums, "hair shaving sharp" is obtainable with much coarser abrasive than the 3um/8000 grit stone you reference. The key seems to be in complete and clean removal of the burr/wire edge after sharpening. I think stropping with a coarse abrasive as described in this thread (http://www.bladeforums.com/forums/showthread.php/1036649-A-balanced-strop) is the easiest way to go, especially if you are going to be doing it freehand, but I haven't tried it yet. I am about to order some of the course grit compound to try it out. I already have the horse butt leather.

If you want me to send you a bit of this stuff to try out the stropping method, send me an email at drunkenpanda_94609_(at)_yahoo_.com (remove the underscores) and I would be happy to send you leather and compound at cost to try it out. You would only need to supply your own glue and wood.

Edit:
typed my email address wrong, but I fixed it :)
 
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mrdeus said:
Since I don't really care for walking around with shaved patches on my arms (or legs), I just check if the edge grabs the hairs above the skin (kind of like the motion you'd use for shaving, but much slower and without touching the skin and you stop as soon as the edge catches the hair). If it does that, it would've shaved too. I mostly use newsprint when test cutting.
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This is how I test as well. I can get this effect with very low grits as has already been stated. I'll continue with grit progression until I'm satisfied, but I typically stop in the 6-800 range and strop that toothy edge. It works best for my needs of a knife.
 
Oh, it just means that your bevel is ground COMPLETELY to the edge of the steel. Do a quick search for "the sharpie trick" for an easy way to ensure that you are. Generally, formation of a detectable burr will indicate that you have fully apexed the bevel. Without a burr, you really can't be sure.
 
Not all hair is created equal.

Asians often have the thickest cuticles of hair. I found out the hard way, 'why is my knife skin splitting buy can't cut my hair?', turns out I can easily cut Caucasian hair with ease but Asian hair is like Teflon coated or something...
 
darcuss said:
This is how I test as well. I can get this effect with very low grits as has already been stated. I'll continue with grit progression until I'm satisfied, but I typically stop in the 6-800 range and strop that toothy edge. It works best for my needs of a knife.
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That's a great working edge right there!!! I usually got to about 1400 grit and strop I am a custom leather maker and pistolsmith so I need a very good edge. The 1400 grit stone I use is a black translucent arkansas and it gives an edge that is flat nuts!!!! I swear by arkansas stones myself they can give a better edge than any dmt product I have ever used.

MM
 
Komitadjie said:
Oh, it just means that your bevel is ground COMPLETELY to the edge of the steel. Do a quick search for "the sharpie trick" for an easy way to ensure that you are. Generally, formation of a detectable burr will indicate that you have fully apexed the bevel. Without a burr, you really can't be sure.
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Oh. I guess I got that down.

HwangJino said:
Not all hair is created equal.

Asians often have the thickest cuticles of hair. I found out the hard way, 'why is my knife skin splitting buy can't cut my hair?', turns out I can easily cut Caucasian hair with ease but Asian hair is like Teflon coated or something...
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Guess I'll have to find a white guy that doesn't mind me shaving his arm then.
 
HwangJino said:
Not all hair is created equal.

Asians often have the thickest cuticles of hair. I found out the hard way, 'why is my knife skin splitting buy can't cut my hair?', turns out I can easily cut Caucasian hair with ease but Asian hair is like Teflon coated or something...
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Yeah, I'm Chinese and I can't whittle my hair. I can shave easy, though. I'm certain jdavis is not Asian.

To the OP, it does get sharper. You can try sharpening a real thin knife (an Opinel or some other traditional, a Centofante 3 or even just a hollow ground) just to see how sharp a knife gets. It's easier to get those to shave.
 
Clean patch, dry, with no pressure.

There are levels above that. You can get a knife sharp enough to jump the hair. Meaning the instant the edge touches the hair, it leaps off in a shower.

Hair whittling sharp means you can take a hanging hair, and shave curls without cutting the hair through. Like little curly shaves of wood.

Bigfattyt said:
I prefer "Hair Whittling"

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Most my carry edges are kept at this level. Once at that level, just a few passes per side on the strop after use, and they stay that way.
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Then there is tree topping sharp, meaning the edge does not need to touch the skin, it will take standing arm hair off without touching skin at all. I have accomplished this type of edge. It is impressive, but really it does not last past a pass through paper.

There are levels of sharpness well beyond these.
 
calvinw said:
Yeah, I'm Chinese and I can't whittle my hair. I can shave easy, though. I'm certain jdavis is not Asian.

To the OP, it does get sharper. You can try sharpening a real thin knife (an Opinel or some other traditional, a Centofante 3 or even just a hollow ground) just to see how sharp a knife gets. It's easier to get those to shave.
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I was thinking that too, which is why I asked about that here: http://www.bladeforums.com/forums/s...od-are-shaving-knives?p=12040951#post12040951 Although, I'm considering trying it with a Higonokami or an Opinel Garden Knife.
 
I bought a Higo off the bay for cheap, around $10. It did not come sharp, the blade was very thick, it was poorly finished. Actually, there was no finish to speak of. It seemed like it was just slapped together, dunked in oil, wrapped in wax paper and shipped. It was a bad knife. Maybe you can get a better one if you pay more than $10. But I would highly recommend the Opinel instead.

Also, when people talk about shaving, they usually mean arm or leg hair, not facial hair. The skin on you face is too sensitive and even though your knife may be shaving sharp, it'll still hurt to shave your face, especially it's a dry shave.
 
You can get even very fat knives hair shaving sharp, even at obtuse angles.

All my Busse are hair shaving sharp.

Thin grind knives, like Opinel, and traditional folders like GEC's, take less effort to get there, because you are removing way less material than you have to from a wide secondary bevel.

I always recommend a strop for getting that hair jumping, hair whittling edge on knives. It is just so easy.
 
That's true, it's possible to get an axe to shave.

Stropping will help you get there too. For me, stropping gets sharper than the Spyderco Ultra Fine stone.
 
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