Hair Popping

[Zamfir]

Ok, so I am learning a ton here but I want to make sure I am understanding something right and pose a couple of questions to the more experienced sharpeners. **Geeking mode activated**

There are all kinds of different steels and alloys out there. Different hardness, densities, bending strength, corrosion fighting, brittleness, cost, etc.. All of the different blends created are tying to find the correct mix of the above characteristics to do the task the knife was intended for. Everything is a give and take. you can make something super hard but it can be brittle, or hard but rusts easy, etc..

Along with all of this are what angles you sharpen to depending on the task the knife is going to be used for but the material also comes into play. Also, not just the material, but what other processes the material went through. I get the drift that 2 different knife makers could have the exact same type of metal from the same ingot batch and depending on how it was hardened and worked and such one could be a turd and one could be kick ass. Some of these processes are very persnickety and a little difference in procedure can make a big difference in the final outcome.

Am I right so far?

Ok, now if I am right, or close to right, –please educate me where I am off in the weeds—

I pose the following question.
Can any blade be sharpened to hair popping?

Are there angle limitations to make a blade hair popping?

If I look at a hair through very high magnification, the hair looks like a palm tree trunk. It almost appears to have scales that are fashioned in a certain direction. In order to be hair popping I am guessing the edge has to be sharp enough to get into or catch one of these “scale like shapes” to cause it to bite in and therefore pop right through. So, is hair popping only going to happen when dragging the hair in the proper direction? Say from root to tip over the edge or from tip to root over the edge? or does it not matter?

It would seem, that in order to obtain such a sharp angle, you would have to have good steel where the molecules are tight enough, (maybe density is the right term?) and aligned in the right way so you could even make the edge that sharp in the first place. If the steel is crappy, you could only get so sharp because you would have microscopic impurities that would chip or fall out at this fine of an angle? Like if you whacked off a hunk of swiss cheese you would have them holes in there, where if it were something more dense you would have a better chance at a smooth edge.

With this being said, if there are angle limitations to making a blade edge hair popping, would there also be steel types that could even be made hair popping?

I do understand that certain angles and weaker steels would just fold this edge over real quick like.. I sharpened my friends cold steel neck knife..I could carve up and push cut paper real easy..He took it and shaved a big section of his arm with it, then I tried to show him how it would push cut paper..nadda.. not anymore! lol. Him shaving his arm like that dulled the knife enough that it would not push cut paper anymore..

I do not currently have many knives to play with.. I have some Buck 110 folders, Kershaw leeks with 14C28N Steel
A Kershaw leek with S30V, a leatherman wave with s30V and an old leatherman with unknown steel, and some Victorinox stainless pocket knives.

I am guessing that the s30V would be the best candidate? If I were to try at some point?

Whew..had more questions and thoughts than I started with..
*Geeking mode off*

Thanks for any info to help an inquisitive newbie out.

[Josh]

Ok, I will pick a few 😉 It would take me a bit to get to all of them!

Can any blade be sharpened to hair popping?

In my experience, yes, although some will be more efficient than others. I have found some steels that have many inclusions and cause the edge to chip out continually while sharpening. You can still get these armhair shaving sharp, but they arent the best. And you are right in that while you can get practically any blade shaving sharp, many won’t hold it for long if they have had a bad ht or something.

Are there angle limitations to make a blade hair popping?

No. You just have to hold the knife at the right angle when shaving arm hair 🙂 Cliff has reported that you can get a 90 degree edge to shave :silly:

If I look at a hair through very high magnification, the hair looks like a palm tree trunk. It almost appears to have scales that are fashioned in a certain direction. In order to be hair popping I am guessing the edge has to be sharp enough to get into or catch one of these “scale like shapes” to cause it to bite in and therefore pop right through. So, is hair popping only going to happen when dragging the hair in the proper direction? Say from root to tip over the edge or from tip to root over the edge? or does it not matter?

this question more applies to straight razor shaving… please read up here on it

[Zamfir]

Awesome article! Thank you! It helps a lot.

[Zamfir]

When I was talking about hair popping I was for sure talking about the hanging hair test hair popping. Shaving is easy with the Wicked Edge. I did manage to get my sv30 kershaw random leek to be hair whittling in one little section..lol. It will cut into the hanging hair but only split it a ways down. Sometimes it cuts all the way through but not anything repeatable. I did not distress my edge before sharpening. Gotta give that a whirl. It may help a bit. That video you posted recently will help a lot Josh. Thanks!

[Zamfir]

Hmmmm..distressed the edge and never went below 600 grit stones. re-apexed at 17 deg per side and kept at that angle all the way through the 1k stones. being cautious of whisper light passes before changing up stones. gave it tons of time on the 1k. still not more than hair whittling. I brought the angle in to 16 and hit it with the balsa 1 then .5micron starting with medium pressure then as light as I could overcoming the suction. edge does look better under the scope but still just hair whittling. no pops. I spent some good time on this tonight. Not sure what I am doing wrong. is hair popping just not possible with the angle and sv30 steel?

Attachments:

• randomleekafterdestress.jpg

[Josh]

It should be possible w/ s30v, sure, but I am not so sure it’s possible off of the 1k stones w/ a couple strops. I think you need some higher grit stones IMHO. I normally go up through my 10k choseras, full mirror, if I want that kind of edge.

[Daniel maloon]

Sure it is. Like Josh said you need a higher grit. .5m is where you would start seeing hair splitting. .25m is where it would be grabbing and popping hair. Above that is where you would start seeing hht 4’s and 5’s. Getting the whole blade at a hht 5 is pretty hard if that’s where you’re trying to get.

[Zamfir]

Okdoke. So I am not into having to use water at this point..yuck. Don’t get me wrong, it is obvious those chorseras kick ass and there is a reason there is a big following of that type of stone. I just do not want to add water and the mess that adds to my setup at this point.

So, with that said I guess I need to decide if I want to go the ceramic route or the glass blanks and sandpaper.

What are the pros and cons for each? I am sure at some point I will have them all as addicted as I am now..but I am still recouping funds a bit at this point.

I am not looking to get a whole blade level 5..that is the silent slicer right? (yup)
HHT-0 – shave:The hair can be shaved immediately at the holding point. This is strictly spoken not a true HHT, but it does tell us that the edge is capable of shaving. [all other attempts must be made at least half an inch from the holding point]
HHT-1 – violin : The hair doesn’t cut, but it “plays violin” with the edge. This is due to the shingles catching the edge, but it’s not sharp enough to penetrate. On a full hollow razor, a faint ringing sound can be heard. On all razors it can be felt with the fingertips that hold the hair.
HHT-2 – split: When it is dragged across the edge, the edge catches the hair and splits it lengthwise.
HHT-3 – catch&pop: When it is dragged across the edge a bit, the edge catches the hair and pops it. The severed part will jump away.
HHT-4 – pop: The hair is popped immediately when it touches the edge. It still jumps away.
HHT-5 – silent slicer: The hair falls silently as soon as it touches the edge.

I am interested in trying to get a whole blade HHT-3 -just a goal for me to hone my skills..pun intended..and it is a cool test to show people that are not sharpening geeks like us.. (the blade is not that big since some is serrated anyway) I am using my beard hair which is way easier to see and works better..my fine hair on my head is crazy small and that will not even violin on my edge..lol. Beard hair works good and I have enough of it. lol.

[tcmeyer]

Do I really need that ’70 SS454 Chevelle? No… Do I really want that SS454 Chevelle? Clearly, yes, but my wife won’t let that happen, which is neither here nor there. But do you really need HHT-3?

I routinely get HHT-2 on my EDC Spyderco by polishing a little on the 1000 grit teeth, but demonstrating that and higher is jus’ showin’ off. With few exceptions, you’re better off with a toothy edge, which probably ain’t gonna get you to HHT-3.

With regard to ceramics vs glass film, I’ve said that 12 and 9 micron film are 1200 and 1800 equivalents, but now I’ll admit that they don’t seem to cut like the 1200/1600 ceramics, which feel gritty but leave a pretty good looking scratch pattern. I’ve also jumped from the 1000’s directly to the 1.4/.6 ceramics with success. It might not remove every trace of the 1000’s scratches, but the edge doesn’t seem to mind.

[Zamfir]

Need? heck no. I just want to be able to replicate it and know I can do it. Just a little goal to help with the sharpening learning.

if you use the glass handles blanks will they be at the same angle as all the diamond plates? Or have I already stepped into needing the same thickness arm gizmos?

[tcmeyer]

I don’t have the WE glass blocks, so I can’t say. I made my own before they became available. I did order a pair of blank handles, thinking to put the glass plates on it, but when it arrived, it had aluminum plates already installed. As I was experimenting, I tried flattening (lapping) the aluminum plates and it turned out pretty good, so I am now using them with adhesive-backed film. I can’t say for sure without checking, but I’m pretty sure they’re the same thickness as the diamond plates.

I have modified almost all of my blocks by installing bronze bushings. My installation method ensures parallelism with the face of the plates, but not equidistance for both sides. This means I have to adapt to the differences with the VSTA (SWAT) adapters, so this has become an inherent part of my process. Put new stones on rod, set the micro-adjusts, begin stoning. It’s maybe a ten or twenty-second adjustment. You can do the same thing with the AngleCube, but that will be maybe 30-to-60 seconds.

I didn’t need to go beyond the 800/1000’s either, but I too was driven by curiosity and the challenge. Like most things I do, I got a little carried away and now I have three pairs of diamond stones, two pair of ceramics stones, five pair of glass blocks (film), one pair of WE aluminum blocks (with film) and two pair of blocks with leather strops. Now I hone with one eye looking over my shoulder, watching for an intervention. :whistle:

[wickededge]

I worked on getting an edge hair popping sharp last week. I wanted to find out if I could get it that way with the 1000# diamond plates, so I worked a long time at it on a Shun santoku at 15 degrees. It was extremely sharp but never hair popping. Then I stropped with the 14/10 micron strops; much sharper but still not hair popping so I went to the 5/3.5 micron strops. 3.5 seemed to be the magic number, suddenly I was passing H4 and sometimes H5 easily. It was a fun experiment and one I’ll definitely repeat with different knives and different angles. I did something similar a while back in conjunction with the sharpness testing machine. I’ll see if I can dredge up those results.

-Clay

[wickededge]

This is one little study I did in 2012:

[table]
[tr]
[td]Hanging Hair Test Matrix[/td]
[/tr]
[tr]
[td]Utility Blade – High Carbon Tool Steel[/td]
[/tr]
[tr]
[td]11.65° per side or 23.30° inclusive[/td]
[/tr]
[tr]
[td] [/td]
[/tr]
[tr]
[td]Medium[/td]
[td]# of Strokes[/td]
[td][/td]
[td]HHT Result[/td]
[/tr]
[tr]
[td][/td]
[/tr]
[tr]
[td]1um Diamond on Top Grain Cow Leather[/td]
[td]100[/td]
[td][/td]
[td]Pass: HHT-2[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’].5um Diamond on Top Grain Cow Leather[/td]
[td align=right]30[/td]
[td][/td]
[td]Pass: HHT-2[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’].5um Diamond on Top Grain Cow Leather[/td]
[td align=right]100[/td]
[td][/td]
[td]Pass: HHT-0[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’]Plain Top Grain Cow Leather[/td]
[td align=right]10[/td]
[td][/td]
[td]Pass: HHT-2[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’]Plain Top Grain Cow Leather[/td]
[td align=right]20[/td]
[td][/td]
[td]Pass: HHT-3[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’]Plain Top Grain Cow Leather[/td]
[td align=right]40[/td]
[td][/td]
[td]Pass: HHT-2[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’]Plain Top Grain Cow Leather[/td]
[td align=right]100[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’].125 CBN on Top Grain Cow Leathe[/td]
[td align=right]10[/td]
[td][/td]
[td]Pass: HHT-2[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’].125 CBN on Top Grain Cow Leather[/td]
[td align=right]20[/td]
[td][/td]
[td]Pass: HHT-2[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’].125 CBN on Top Grain Cow Leather[/td]
[td align=right]40[/td]
[td][/td]
[td]Pass: HHT-2[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’].125 CBN on Top Grain Cow Leather[/td]
[td align=right]40[/td]
[td][/td]
[td]Pass: HHT-1-2[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’].25 Diamond on Top Grain Kangaroo
Leather[/td]
[td align=right]10[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’].25 Diamond on Top Grain Kangaroo
Leather[/td]
[td align=right]20[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’].25 Diamond on Top Grain Kangaroo
Leather[/td]
[td align=right]40[/td]
[td][/td]
[td]Pass: HHT-1[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’].25 Diamond on Top Grain Kangaroo
Leather[/td]
[td align=right]100[/td]
[td][/td]
[td]Pass: HHT-3[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’].125 CBN on Nano-Cloth[/td]
[td align=right]10[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’].125 CBN on Nano-Cloth[/td]
[td align=right]20[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’].125 CBN on Nano-Cloth[/td]
[td align=right]40[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’].125 CBN on Nano-Cloth[/td]
[td align=right]100[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’]Plain Horse Butt Top Grain[/td]
[td align=right]10[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’]Plain Horse Butt Top Grain[/td]
[td align=right]20[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’]Plain Horse Butt Top Grain[/td]
[td align=right]40[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’]Plain Horse Butt Top Grain[/td]
[td align=right]100[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’]400# Diamond[/td]
[td align=right]100[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’]600# Diamond[/td]
[td align=right]100[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’]800# Diamond[/td]
[td align=right]100[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’]1000# Diamond[/td]
[td align=right]100[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’]1200# Ceramic[/td]
[td align=right]100[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’]1600# Ceramic[/td]
[td align=right]100[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’]5um Diamond on Top Grain Cow Leather[/td]
[td align=right]100[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’]3.5um Diamond on Top Grain Cow Leather[/td]
[td align=right]100[/td]
[td][/td]
[td]Fail[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’]1um Diamond on Top Grain Cow Leather[/td]
[td align=right]100[/td]
[td][/td]
[td]Pass: HHT-4[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’].5um Diamond on Top Grain Cow Leather[/td]
[td align=right]100[/td]
[td][/td]
[td]Pass: HHT-4[/td]
[/tr]
[tr height=20 style=’height:15.0pt’]
[td height=20 style=’height:15.0pt’].25um Diamond on Top Grain Kangaroo
Leather[/td]
[td align=right]100[/td]
[td][/td]
[td]Pass: HHT-5[/td]
[/tr]
[tr height=0 style=’display:none’]
[td width=297 style=’width:223pt’][/td]
[td width=80 style=’width:60pt’][/td]
[td width=17 style=’width:13pt’][/td]
[td width=141 style=’width:106pt’][/td]
[/tr]
[/table]

-Clay

[wickededge]

Here is a Dropbox link to the more recent study: Sharpness by Grit You’ll need Excel or other spreadsheet program to view it. Be sure to check out the various tabs where I studied stones and strops and edge retention. There are HHT results for all the grits in the later tabs as well.

*It looks like the spreadsheet will open in your browser (at least in Chrome and IE) and the tabs are available.

-Clay

[Todd Simpson]

Maybe it helps to see the cross-section of a hair (or whisker in this case)

There is a hard keratin shell a few microns thick surrounding a soft inner cortex.

The HHT is a two step process; first, catching and penetrating the keratin shell and second, completing the cut. “Catching” only involves the last micron of the edge and the keenness or edge width of the very edge. Cutting or force to cut will involve not only keenness but bevel angle, and friction from smoothness/polish/coating of the bevel over the next 100 microns or so (diameter of the hair).

I would suggest that “popping” occurs because the force to cut is high enough to stretch the hair, causing a pop when it finally cuts. HHT 5 is “silent” because the force to cut is so low that little or no stretching occurs.

[Author]

Posts