avoiding hanging hair test confusion

all of us are looking for tests to useon out blade that may be a bit quicker than an actual shave test, to that end many rely on the hanging hair test (HHT). After a significaant absence from this baord I have returned and read many comments and questions regarding this test. It is apparent that there is much confusion.

it must be realised that for a GIVEN blade to cut a GIVEN hair in the HHT there are 2 predominant factors. first factor we would call sharpness, in reality sharpeness is an edget hat has been honed so that the edge is very very thin. the second factor is what i call "toothiness" this factor has to do in reality with how rough the actual edge is. is the very edge a jagged jumble of steel protrusions that can easily grab a hair? or are there smooth transitions at the edge that makes it more difficult to grab a hair? Therefore keep in mind the following

passing the HHT is a function of (A) sharpness and (B) toothiness

a balde that is not so sharp yet toothy can pass the HHT. take that edge and smooth it out a bit and it does not.

some examples and maybe some things to look for.

let me preface these by stating I always get my blades to pass a HHT after the hones and before a strop


case A. Honing on the 4000 grit norton. It is not that difficult to get a blad eto pass the HHT off of the 4000 grit side of teh Norton. I can do it. Others can do it to with some honing skill. try shaving with that blade and the results will not be pleasant as there will be irritation. you may not feel the irritation during the shave but you will notice it later. I know this from experiance. Now if you take that blade that can pass the HHT off of the 4000 grit norton and give it a few passes on the 8000 grit nortin there is a good chance it will no longer pass the HHT. Why is that?? its because teh blade has lost some of its toothiness and can no longer grab a hair. if you keep going on the norton you will eventually be able to pass the HHT because the lack of toothiness is made up for by an increase of real sharpness. some people can get a good shave off of this with only leather stropping afterwards.



case B honing on the 8000 grit norton, moving to coticule. you get a blade poppling hairs off of the 800 norton and give it a few passes on the coticule and it nowlonger passes the HHT. Has the edge become duller?? NO! not unless you have a course coticule which is possible, More that likely the coticule has resuced the toothiness and therefore hindered the blades ability to pass the HHT . even though the blade no longer passes the HHT it should provide a smoother shave than what you would have gotten if you had not moved to the coticule.



Case C diamond vs crome oxide. you use a pasted strop with diamond paste and notice that it easily pops hanging hairs or arm hairs, you move on to a chrome oxide paste and it doesnt do so quite as neatly. you havent gone up in grit size so what is the deal? the deal is that the chrome oxide doesnt produce as toothy an edge as the diamond, which is incredibly hard, does. even though the new edge doesnt perform as well on the hair tests it still is sharper and should provide a better shave.


im summary, when you are assessin the edge of a given blade usign any kind of hangint hair test remember that sharpness is only one of the factors that dicate if the blade passes or not. the other factor will help the blade cut a hanging hair but may or may nto contribute to a good shave.

Great info. Thanks for helping me understand the HHT a bit better.
Now to tackle the King Cutter!:(
Cheers

My razors all pass the HHT fine after the coticule and/or Escher; however, not passing the HHT after the coticule seems to be a very common complaint. I am not really sure why this is, maybe it is my hair (or the badgers), honing technique/progression, or stone that is different :shrug:

Quote:

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Originally Posted by heavydutysg135

...maybe it is my hair (or the badgers...:shrug:

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Nice point. When I just couldn't pass HHT consistently with my fine thin short hair, I decided to try with a single badger hair. Well blow me down if suddenly every blade of mine passed HHT!

Just one thing... feels like I'm cheating the spirit of the HHT. :o

So now I use a badger hair to pass HHT and give me an indication of being on the way. Then I hone some more and if it snags my own hair it's ready for a shave test.

I had trouble passing the HHT off the coticule for a while when I first started using it. As I increased the number of strokes I did and lightened the pressure toward the end, the results improved.

In many cases, I get a scary HHT result by doing 50 strokes on the coticule after the Belgian blue, with the last 10 being as light as I can make them. My Dubl Duck Goldedges are truly frightening after this. :)

Sometimes, though, the razor doesn't seem to do well the HHT no matter what. I think it depends on the blade, partly.

Using the coticule after the Norton 8K is a little different than using it after the Belgian blue, it seems. Bruno mentioned that doing more than 10 or so strokes after the 8K seemed to degrade the edge rather than improve it.

I have a theory about this that I can't prove: I think there are transitional phases if you switch between very different types of hones. The Norton/coticule transition is one example. I've heard there can be a similar effect when going from Shaptons to a natural hone.

I think a particular hone sets up a certain scratch pattern that is more compatible with hones in the same progression. So you get one result if you go from a Belgian blue to a coticule, and you get another if you go from an 8K Norton to a coticule and still another if you go from a Shapton to a coticule. After jumping to a different style of hone, there's a transition phase before the coticule can erase the previous hone's work.

Anyway, just something I've been kicking around for a while... Could be totally off base. :shrug:

Josh

I've been talking with Howard from theperfectedge (who's been talking to others) re a standardised "hair" experiment for the HHT to remove the variability associated with different hair types. Nothing's happened yet, but it will make some interesting research when it does, I'm sure.

In the absence of a standard all these sharpness tests are, or should be IMO, self-calibrated, particularly the HHT. Correlate the shave with what the blade does in your chosen test(s), iterate that process a few times, and eventually you know how the shave will be from how the particular blade passess the HHT or the TPT, or the arm-hair test (AHT) or whatever.

Scott (Honedright) told me this a way back and it's one of the best pieces of advice I've ever received regarding shaving.

James.