Thread: HHT

Originally Posted by Bart

PCB,

I'm sorry for making such a harsh statement to your post. What you could not know, being relatively new to the forums, was that on every single thread about the HHT, people that use nor know the HHT, chime in to tackle all intelligent discussion with the "parlor trick" dismissal. I kinda had it with that, but I shouldn't have directed that to you.

As for the HHT, you might have no use for it right now, or not even ever at all. I don't know if you are honing your own razors, but if you do, or intent to in the future, here are a few finer points that I consider important for turning the HHT in a successful probing method.

1. Use clean human hair, that was harvested when it was freshly washed. I recommend keeping a small strand of hair with a length of about 2.5" in a little container, so you can always rely on the same hair.
2. Hold the hair between thumb and index finger at the root side. The outer hull of a hair, called "cuticle" is a single layer of cells arranged like roof shingles. Once the edge of a razor catches between those shingles, their is no escape: the hair will be severed (or sliced lengthwise). For this reason the hair must me held at the root side and the razor may be angled slighty to allow it to catch the hair better.
3. Moisten the hair prior to the test. Hair is extremely hygroscopic. The inner part takes up moisture very quickly, expanding and causing the cuticle shingles to open up a bit. This is the main reason why we prep our beard prior to shaving it, and for the same reason we should prep the hair before performing the HHT.
Furthermore, wetting the hair rules out any significant differences in relative humidity that may affect the outcome of the test at various moments. A valid way to moisten the hair, is to run it between a wetted thumb and index finger and wait a few seconds for the hair to adapt.

When these 3 terms are met, the HHT becomes much more calibrated, and you'd be surprised how consistently it can tell you things about the edge at various honing stages.

There are several results to be discerned. Here's my personal scale:
HHT 0 (zero): 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 attempt must be made at least half an inch from the holding point)

HHT 1: 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.

HHT2: When it is dragged across the edge, the edge catches the hair and splits it lengthwise

HHT 3: 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: The hair is popped immediately when it touches the edge. It still jumps away.

HHT 5: The hair falls silently as soon as it touches the edge.

These results all have different meanings at different honing stages. For further explanation, you'll have to await my wiki article on this topic, but I can reveal that I find the HHT especially usefull for knowing when a bevel is fully developed and also for reaching the desired keenness before finishing the edge and during the very first stropping session (which is often underestimated, imo).

Best regards,
Bart.

This is the best and most detailed description I've heard on the HHT test. I can't wait for your wiki entry, it will be an invaluable addition. I guess I've been doing it all wrong, I'm now curious to try it the way you do. Particularly the wetting the the hair and tilting the razor slightly parts.

Bart: I truly appreciate your generous response.

As you know, I am new to this. I had no idea that the HHT was as specific in detail as your description. I've seen a few videos, and it appeared to me that one just grasped the hair (I knew it was near the root) and did it. Seemed very simple.

I will follow your instructions and keep at it. Interestingly, after stropping my Bismarck about an hour ago (also still trying to get the stropping thing down, so I did 30 on the linen and about 100 on the Latigo for the practice), I had a revelation. For the first time, I could feel the "stickiness" of the TPT. Felt it a little too well, actually, but my satisfaction at finally "getting" that test was greater than the discomfort (no blood, just a visible slice -- doesn't hurt now). Flush with triumph, I found a hair in the sink (it was wet, at least) and tried the HHT. Pop, pop, pop, up and down the length of the blade!

These small epiphanies in straight shaving occur almost daily, and are a great source of joy for me. I appreciate your effort to educate me, and I hopethat one day I will have the knowledge to help others learn this fascinating art.

Great post Bart !!!!

However I am now checking the shave den to see where it was that you hid the freaking camera......

Wow Bart, I have never read such a thorough description of the HHT!! But I like it.

Thanks Bart. That put a whole new spin on the HHT for me. I've never been able to get the HHT to work for me, even with str8s honed by professionals here. I can't wait to give your HHT method a try.

Looking forward to that Wiki article, Bart. Thanks.

Someone (forgot who) made a post telling that he hones on 4k until the blade passes the HHT and then he moves to 8k.
I've honed and honed and my str8 barely passes HHT, then I give up hope and move to 8k.
I have a good quality high carbon/full hollow ground Tennis (Solingen) str8...my thanks to gugi.
What do you guys think?

In my opinion if a razor passes HHT off norton 4000 it's not ready. There are very few razors that are an exceptions to this, but even those would require a very experienced hand to get it.
Its not hard to cut hanging hair with a jagged edge, but a good edge should be smooth. I don't believe the 4k norton can produce that edge unless the steel is very special (I once shaved very comfortably with a razor off dmt-1200, but it took me probably an hour of honing before that, very tough steel).

Off the 4k level the razor should shave armhair easily. If it almost passes hht at 8k, I'd say go to the strop. It would be good to have a canvas piece, but since you don't you can make one from an old pair of jeans - that cotton works very well.
Also your strop is horsehide which in my opinion is quite efficient, so perhaps just trying that would work very well too. Test the HHT as you strop, you should notice how the way the hair is cut changes.

I would say at this stage just doing Lynn's pyramids between the 4k and the 8k is enough. It should only need few strokes, just the right ones. You'll get the hang of it.