Giving Hysteresis a Fair Test

[woodfluter]

OK, decided to re-visit twin-blade cartridge shaving today with my new, improved skills. Not throwing something in a bag for overnight air travel, I mean giving the notorious Hysteresis Effect a fair trial, with good lather, new cartridge, patience. And comparing that to the results I get with my SE and DE razors.

Here's my motivation. On the blade subforum, Steve (SiBurning) recently reminded us of this wonderful study he dug up awhile ago:
On the Optimum Hand Speed for Two-Blade Razor Shaving

It appeared in an applied math teaching publication, but it's worthy of submission to JIR (Journal of Irreproducible Results). Serious analysis combined with humor and silliness.

Anyway, with a boatload of assumptions, they come up with an optimal velocity of about 1.4 inch/sec, and apparently erring faster is better. My usual range is about 1.5-3.0 inch/sec, which brackets it nicely.

Now the real and larger question is whether the "hysteresis effect" actually works in the real world, with all the added complexities the authors recognize.

Tools & Approach

-- Fresh Trac II cartridge in a 1970s vintage heavy brass handle.
-- Mitchell's Wool Fat shaving soap, bowl lathered. [edited...not "Miller's"]
-- My usual ~4 passes (WTG>XTG>ATG + extra work on chin and neck.

I chose a non-pivoting head to let me have some degree of control over angle, maybe, just a little(?)

Experience

Well. It certainly was cutting very smoothly and easily on the cheeks. Not really bad on the chin. But no fewer strokes needed there. About the same. Problem is, this is super mild. I had to press down somewhat harder to get it close on the chin, despite the two blades. And very little control over shaving angle. It is what it is.

The initial impression was one of slick effectiveness, but that faded a bit on the chin where I was experiencing some irritation from the pressure needed to cut closely, and really receded when I got to my neck. Lots of strokes, re-lathering, more goes at it with increasing pressure.

So guess what...I actually cut myself on the neck. Hasn't happened in a very long time. I got careless with all the approaches I was trying to get anywhere. I regularly use all these dangerous-looking razors with impunity, and cut myself on a cartridge. Sheesh.

Well, I finally got a close shave...with some neck and chin irritation. The next part, the real test of the hysteresis effect, is going to be how much stubble I have 24 hours later. I'll let you know tomorrow. If hysteresis works, it should have cut closer and there will be less stubble. If not, I'm calling this the hysteresis defect.

- Bill

 

[BZiel]

I heard Hysteresis was no longer curable with antibiotics.

Thank god I only use straights.

 

[mblakele]

Interesting idea.... But what is "Miller's Wool Fat"?

Just to give Gillette the benefit of the doubt, maybe they approached hysteresis with a different goal in mind? It seems to me that there product design goal would not have been to shave even closer than a DE. Who was asking for that as a new product feature? Instead I think they would have aimed at a similar shave, but with less skill required. If hysteresis is real, the razor can be milder. The blade can stay farther from the skin and still cut the hair to a similar length.

Of course there is no such thing as a flawless design. In troublesome places the milder double-blade does not cut well enough, and adding pressure throws away its advantages.

 

[woodfluter]

Interesting idea.... But what is "Miller's Wool Fat"?

Oh, that's the same thing as Mitchell's Wool Fat, relabeled for people with CMS (can't remember...stuff).

Just to give Gillette the benefit of the doubt, maybe they approached hysteresis with a different goal in mind? It seems to me that there product design goal would not have been to shave even closer than a DE. Who was asking for that as a new product feature? Instead I think they would have aimed at a similar shave, but with less skill required. If hysteresis is real, the razor can be milder. The blade can stay farther from the skin and still cut the hair to a similar length.

Excellent point. The authors of the cited article assumed a closer, longer-lasting shave was the goal. But yes, shaving equally close with less pressure or fewer passes might be an alternate outcome. Well, so far that doesn't seem to be happening for me. Maybe if my standards were lower.

 

[woodfluter]

OK, update overdue...

24 hours after the Trac II shave, noticeably more stubble than usual, especially on chin and neck. So I had to press harder to shave as close as I did, leading to a bit of irritation, but it still didn't get as close as a light touch with DE or SE. Not looking good for hysteresis.

I then shaved with a Gem 1912 SE and got a fine, close, easy shave.

Today, more comparisons. Trac II again, vs Gillette Milord with a Yellow Gillette 7 O'clock blade on its 11th shave.

One side of face with one, other side with the other...WTG + XTG.
Then another pass in the same XTG direction going over with the Milord to compare how much was left over (can hear and feel the hairs being cut). Then ATG. No question about it, the DE found more hairs to cut on the cartridge-mown side, even on the flat cheeks. The cartridge still does a poor job on the neck, and sort of poor on the chin unless I really press down hard.

My conclusions:
- I can get a reasonable shave with either, if standard is low.
- For BBS, takes more pressure and more passes on the chin and neck with the cartridge.
- More stubble appears next day after cartridge shaving, despite going for BBS.
- There's more likelihood of irritation with the cartridge if going for BBS.
- I can get a closer shave with traditional razors, with less pressure.

Now there may be two things going on, (a) the putative hysteresis effect that lets subsequent blades cut the hair progressively closer to the face, and (b) the blade exposure and design factors that may favor "mildness". I don't know if some other cartridges are more effective than the Trac II; from experience I'd say the Sensor and Schick Xtreme 3 are equally mild, and hence require equal pressure. But those seem to give you no real choice or control because of the head pivoting, which I initially liked (when I didn't know much).

OK, so far I can't see any evidence that hysteresis really works for shaving.

 

[kingfisher]

Thanks for the interesting posts.

I'm pretty sure that the original goal was to allow people to get a decent shave with fewer passes, not a way for them to get a closer shave.

 

[mblakele]

Looking at old ads, though, it seems like Gillette tried their best to imply that the Trac II would deliver a closer shave - without quite lying.

"No one blade can match the Trac II for closeness and safety combined" in Popular Science, "Because two blades give you extra shaving efficiency, Gillette has been able to set the blades at a very safe angle..." in Life, or this one in Jet that repeats the word "close" without promising a particularly close shave. Readers could easily get the impression that the Trac II would shave closer than a DE, unconditionally. But I think all that they literally claim is that one stroke will shave a closer, and the whole shave will be a better balance of safety and closeness.

Here is a contemporary analysis, from a summary of a study done for ASR in 1971. I wish I could find the entire report.

http://tobaccodocuments.org/product...on=above_foramatted&start_page=49&end_page=49

In summary, results of this work showed that the Trac II system was slightly more efficient than a double-edge razor in whisker removal, but the difference was only about two to five percent, rather than the forty percent claimed by Gillette in some preliminary publicity on the Trac II promotion. On complete shaves, however, double-edge razors were six percent better.

They also tried removing one of the blades from the cartridge, and concluded that two blades were only "a shade" better.

 

[SiBurning]

Hate to be a killjoy, but it seems like you're actually comparing two different kinds of razors and blades, rather than directly testing hysteresis. If you're trying to test hysteresis, you should be eliminating as many other variable as possible. I'd suggest comparing a single blade in a razor vs a pair of such blades in the same razor with something separating the two blades. There would still be too many variables, but many differences would be eliminated. Ideally, you'd merely replace the second blade with a non-cutting surface, since this seems the only way to eliminate the skin stretching of the second blade.

The evaluation is also problematic. (see Perceptions about Shaving) The length of stubble and the density of hairs both contribute to the feeling of smoothness or roughness, and skin condition is also a major factor. If you're pressing harder, causing more irritation, that might affect the smoothness of skin, altering the perception of smoothness.

I've also had discussions with straight razor users about how the stubble seems to grow back thinner, as if a straight cut some hairs more deeply than others. Conversely, a razor with a wide, flat head might result in a flatter, more even cut among hairs. On short stubble, the angle of the cut might be a factor in the perception of roughness. So a more even shave might grow back in a way that is perceived as rougher, though any comparison between such an even shave and a more varied shave would be dependent on the time since the shave.

 

[cb91710]

IOTW: YMMV