Hanging hair test epiphany

S

sja2249

Joined
Feb 11, 2006
Messages
174
Well... I learned some things tonight.

Apparently, the hanging hair test works best with relatively "fresh" hairs.. meaning hairs that were recently on someone's head. I've been trying to do the hanging hair test with hairs I scavenged from the drain, etc. It's a *LOT* easier to do a HHT with a fresh hair...

The test is still mostly about skill. Even with the very sharpest razor, it seems that the HHT requires technique.

These are the little tidbits I've picked up:

Hold the hair by the end opposite the root.
Hold the hair so that it curves towards the blade.
The closer you cut to fingers holding the hair, the easier it is.
Being able to cut further away from your fingers indicates a sharper blade.
If the hair is too dry, it may not pop or may split
It may take several attempts to actually pop a hanging hair even with a blade that is fully capable.

If anyone has any other tips, or things I've mispoken, I'd love to hear back. :)

Sam
 
Hello

I noticed quite the same thing, i have shaved my 9 years old goatee beard and kept preciously all the hairs for edge testing and it seems quite harder to split and whittle them while at the same time i can sometime treetop hairs from my leg using the same blade. They are around 0.1 mm thick and while they were fresh i was once able to split one six time using my police3.
Also even being quite stiff i cant whittle them from 4-5 cm away from my fingers using again that same treetopping edge.
 
I find all these posts about "hair splitting-whittling" very interesting reading. I am not making light of the ability to produce such edges, but wonder what use there is for such a knife. Is it only a plateau to reach in your ability to sharpen a knife, or does it have a useful purpose? Don't get me wrong, I would love to produce an edge that would do these things if I had the equipment to do so. I just don't know what I would do with the knife once I got it to this stage of sharpness. I would be afraid to actually use it after all the work involved in achieving this feat. Am I missing something?
 
OHALLUM said:
I find all these posts about "hair splitting-whittling" very interesting reading. I am not making light of the ability to produce such edges, but wonder what use there is for such a knife. Is it only a plateau to reach in your ability to sharpen a knife, or does it have a useful purpose? Don't get me wrong, I would love to produce an edge that would do these things if I had the equipment to do so. I just don't know what I would do with the knife once I got it to this stage of sharpness. I would be afraid to actually use it after all the work involved in achieving this feat. Am I missing something?
Click to expand...

I can't answer for anyone else... for me, it was just to see if I could do it. I've been sharpening by hand for almost 25 years. I generally find that the most useful edge for me is just sharp enough slice hairs off my arm... I can leave the edge relatively toothy and it will last quite a while. If I get sharper than that with my EDC, sometimes the edge won't bite on some of the stuff I cut.

I have yet to determine how durable the edges are that pass the hanging hair test... They work great for slicing plums... ;)

Sam
 
I do it for the challenge mostly yet i like my EDC at least shaving sharp. I dont put that much time getting to hairwhittling sharp, at least compared to when i started sharpening and stropping, however i have still a hard time reaching treetopping sharpness consistantly and due to time and efforts involved i still consider them as a novelty thing.
 
ohallum, knives that sharp are what i call "novelty edges" meaning they are neat to have for fun but serve no real purpose since an edge that fine will roll if used to cut anything other than hair. it would be like trying to cut a bunch of cardboard with a straight razor. if you talk to any knifemaker that knows what they are talking about, they will tell you the same thing.

i dont think you're missing anything but if you really want to see a sharp blade, check out a shave ready razor. a member from straightrazorplace sent me a shave ready razor and the edge on it is amazing. i can get a knife sharp enough to whittle a hair as if it were a toothpick but a shave ready razor is way beyond that. if you want to read more there, click the link in my sig line and check out the links on my home page.
 
My edges arent thin that they will chip, most of my knives are at 40 deg back bevel and stll can whittle hair.
The novelty aspect is about the time / reward ratio i agree that you will lose the crazy sharpness with a few cuts but your knife wont go butter dull right away.
 
stalag2 said:
I do it for the challenge mostly yet i like my EDC at least shaving sharp. I dont put that much time getting to hairwhittling sharp, at least compared to when i started sharpening and stropping, however i have still a hard time reaching treetopping sharpness consistantly and due to time and efforts involved i still consider them as a novelty thing.
Click to expand...

I can understand the challenge of achieving that level of sharpness, if for no other reason than "bragging rights". I have an old knife that I got from my father-in-law when he died, that has a pretty sharp blade on it. I don't know what it is made of other than some type of stainless. It is a lock blade similar to one made by case, but has no name on it. My "challenge" is to get it as sharp as I can with only my paper wheels, and some different grades of wet/dry sandpaper, and a balsa strop. Can't afford or really don't need diamond stones or a guided angle sharpener for my needs. This is more or less a "retired hobby" for me.
I have a Kershaw tremor for my work knife, and I have it sharp enough to cut hair from my finger tips, which is sharp enough for my normal use. Its all fun.
 
You scavenged hair from the drain? Gross dude.

Come on guys just shave the hair off your arm or legs.

But I understand how it is to be obsessed with sharpness.
 
I have found that once you can achieve this level of sharpness, it's mostly a quality control measure to see how well you sharpened your blade.

I've gotten edges that will whittle my beard hair using my coarsest stone, a 220 grit King water stone. Drop you're edge angle down to less than 10 degrees per side, and finish on a coarse stone with as sharp an edge as you can get. It will do dedicated cutting/slicing chores for a LONG time. I've also gotten edges that will whittle head hair after just a 1000 grit King water stone and a Fine India stone also. These are pretty good general purpose edges, and can both push cut and slice adequately.

I've gotten edges off my Sharpmaker that would still tree top arm hair after cutting 20 feet of cardboard with the same 2" of blade length. The high sharpness doesn't leave as quick as a lot of people think. It shouldn't come as a surprise that sharper edges initially cut longer, as long as they are done properly. There must be no burr left, and suited to the task. For cardboard, I like a high polish edge. I can just push it through with little effort, and keep doing it for a long time.
 
me2 said:
I have found that once you can achieve this level of sharpness, it's mostly a quality control measure to see how well you sharpened your blade.

I've gotten edges that will whittle my beard hair using my coarsest stone, a 220 grit King water stone. Drop you're edge angle down to less than 10 degrees per side, and finish on a coarse stone with as sharp an edge as you can get. It will do dedicated cutting/slicing chores for a LONG time. I've also gotten edges that will whittle head hair after just a 1000 grit King water stone and a Fine India stone also. These are pretty good general purpose edges, and can both push cut and slice adequately.

I've gotten edges off my Sharpmaker that would still tree top arm hair after cutting 20 feet of cardboard with the same 2" of blade length. The high sharpness doesn't leave as quick as a lot of people think. It shouldn't come as a surprise that sharper edges initially cut longer, as long as they are done properly. There must be no burr left, and suited to the task. For cardboard, I like a high polish edge. I can just push it through with little effort, and keep doing it for a long time.
Click to expand...


Great post! Lots of truth.
 
richard j said:
ohallum, knives that sharp are what i call "novelty edges" meaning they are neat to have for fun but serve no real purpose since an edge that fine will roll if used to cut anything other than hair. it would be like trying to cut a bunch of cardboard with a straight razor. if you talk to any knifemaker that knows what they are talking about, they will tell you the same thing.

i dont think you're missing anything but if you really want to see a sharp blade, check out a shave ready razor. a member from straightrazorplace sent me a shave ready razor and the edge on it is amazing. i can get a knife sharp enough to whittle a hair as if it were a toothpick but a shave ready razor is way beyond that. if you want to read more there, click the link in my sig line and check out the links on my home page.
Click to expand...

i dont know what steels have rolled on you but my hair splitting edges hold up extremely well. I have steels : vg10 (18dps) , n690 (20dps), S30v (18dps), m390 (15dps), aogami super (13dps), 13c26 (15dps) CTS BD1 (15dps) , all sorts, none of them have rolled at that level of sharpness. I think its far from a novelty edge - I mean, I can see where you're coming from, for some, its excess work, but when you get the skill to get a knife that sharp in less than a minute - hell, even 30 seconds, like I can, why not do it? especially when it ramps up cutting performance for the first several cuts
 
At this level of sharpness, what do you think the thickness of the apex - 100nm?

Travis - '..under a minute..' - wow, sincerely please share your techniques. Currently, I'm learning+R&D on edge geometry & durability.
 
Ok, for a few years I always thought my sharpening was flawed, ecause it was very difficult to cut standing hair or whittle the hair strand.

Turns out Asian hair is nearly 2-3 times thicker than Caucasian hair...


As for stropping, it gets hair splitting sharp, but hair shaving sharp only stays sharp for about 5 minutes in a sushi bar.

I prefer my own custom convex bevel on a 8000 grit water stone that can almost cut hair but last for over a week for sushi.
Grabbed my friends hair all my knives slice his hair like butter... But not my hair.
 
bluntcut said:
At this level of sharpness, what do you think the thickness of the apex - 100nm?

Travis - '..under a minute..' - wow, sincerely please share your techniques. Currently, I'm learning+R&D on edge geometry & durability.
Click to expand...
whoa sorry i didnt see your comment, I should make a video sometime and PM you :)
 
Durability hasn't been too bad on my Opi which I went from using as a sharpening testbed (20° inclusive, will cut hh) to a bass wood carver. I wanted to see what would happen to the edge (light rolling, stropable) and to see how it compared to a purpose made carver. The polished acute edge cuts into the wood better than anything else I've tried, and even after extended use still cuts better than the more obtuse convex edge on the handmade carver. I will say that the convex edge is better at curling the wood away from the work which is useful.

I thought my Opinel was useless after sharpening and polishing it to death, but it's very useful albeit in another specialized role.
 
For fun, I use some thin kitchen knives that will split hairs,
in particular some laminated Japanes Henckels in ZDP 189.

They feel a bit weird on plastic cutting boards, the way they try to skate,
and last night I had to chop fresh rosemary very slowly because each cut
was sending the bits flying everywhere (I theorize that a slghtly duller knife
(smashes / bruises a bit and the pieces to stay more in place while chopping).
 
You must log in or register to reply here.
Back
Top