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Hanging Hair Test (HHT) For Knives --- Useful Metric Or Parlor Trick?

Posted by jasonstone20 
Hanging Hair Test (HHT) For Knives --- Useful Metric Or Parlor Trick?
September 15, 2019 06:28PM
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I have asked some experienced sharpeners about using the HHT for knives. Even for straight razors, the HHT is controversial. It appears to not be a useful metric for knives that are used for EDC or the kitchen. I have had mixed results, and although I can get knives to pass an HHT, it really doesn't tell me anything useful about the sharpness, other than it can pop hairs. The tree-topping arm hair seems to be a better metric from the people I have asked, and in my own experience that and popping beard hairs seems to work better. There is nothing an knife edge that passes a HHT can do that a blade that tree-tops arm hair can't do in EDC use and kitchen use. In face, chasing a HHT 3/4 can damage the edge leaving you with an unhealthy edge that won't have good edge retention. If an edge can pass a HHT and readily pop head hairs straight off the stone or a small amount of work on a strop, great, but if not I really don't think it is worth chasing. I have been doing that for a few years, and I think it is a waste of time.

Edit:
PS: Also, if you do get a knife to pass a HHT 3/4, if you let it sit overnight, not used, it often will not pass the test in the morning. Plus if the knife is under 15*DPS/30* Inclusive, it usually will pass easily, and if it is over 15*DPS it will just whittle the hair, not pop it completely in half.

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"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston
__
"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp
__
"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes
__
"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
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StoneSharpEdges

Jason D. Stone on YouTube



Edited 2 time(s). Last edit at 09/17/2019 06:16PM by jasonstone20.
Re: Hanging Hair Test (HHT) For Knives --- Useful Metric Or Parlor Trick?
September 18, 2019 06:30PM
I have a strange obsession with getting knives to pass a HHT 3/4 and still slice paper towel. I am trying to use the arm hair tree-top, but I still try to get the knife to pass a HHT 3/4

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston
__
"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp
__
"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes
__
"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges

Jason D. Stone on YouTube
Re: Hanging Hair Test (HHT) For Knives --- Useful Metric Or Parlor Trick?
September 19, 2019 01:57AM
Concerning the whole HHT, I understand that it's mostly a more gimmicky thing that can vary wildly from a number of factors, but just like slicing paper it's a test with a definitive Pass/Fail result, which is enticing as far as testing goes. Plus, it's difficult to combat years of placing that test as the apex (pun intended) of all tests.
Re: Hanging Hair Test (HHT) For Knives --- Useful Metric Or Parlor Trick?
September 20, 2019 02:36PM
Luis,
Yeah, that's is one issue about the HHT, it isn't just pass or fail. The issue I am trying to solve is how to get a reliable, pass fail test for high sharpness, ie above shaving sharp. One item I tried that I think might be doable is cigarette paper. Also, I think a sharpness tester like the popular one might be an option. I built one myself, it just isn't the easiest thing to use.

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston
__
"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp
__
"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes
__
"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges

Jason D. Stone on YouTube



Edited 1 time(s). Last edit at 09/20/2019 02:37PM by jasonstone20.
Re: Hanging Hair Test (HHT) For Knives --- Useful Metric Or Parlor Trick?
November 06, 2019 04:44PM
I just measured my OCB Hemp Papers vs JOB Single Wide Papers, and they are the same thickness, so if you can't find the OCB papers, the JOB should work.

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston
__
"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp
__
"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes
__
"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges

Jason D. Stone on YouTube
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