Science behind # of blades

[fiacobelli]

Hi All,
I've been looking for science behind shaving methods, blades, and lubrication. In my quest, I found a very informative article about the science involved in engineering Gillette razors.

The article describes hair, skin and how when the hair and the follicles are moist, they are softer to be cut and softer on the blade. It describes how lather works as a moisture keeper.

It also explains how when the hair is touched by the blade it is also pulled a little by it before being cut. It stays pulled for about 1/8 of a second and then it retracts. This gives 2 blades a good reason to exist. The second blade can engage the hair while stretched and cut it lower.

In addition, in their studies, 2 blades proved to give individuals 2 hours more before noticeable hair growth appeared. This, compared to single blade shaved individuals. Of course to compare this, all other things must have remained equal, including the number of passes. I am convinced, by personal experience (about a month) and by reading the posts, that an equally close shave can be obtained with a DE (only with more patience).

Lastly, they explain the ideas behind the Sensor brand: (a) The lubricant they use to help the blades slide (PEO), which is used to make submarine torpedoes go faster and smoother under water; and (b) the wires between the blades to avoid clog.

My take away though, is that with a moist face and careful technique one could shave well with almost anything sharp enough to cut hair. Two blades or one are a matter of cost, preference, skills and time, provided that the blade(s) is(are) good quality.

The article:
J.C. Terry (1991).Materials and Designs in Gillette Razors. MATERIALS & DESIGN Vol. 12 No. 5.

 

[michiganlover]

Science?? No, it's suedo-science. Gillette invented some theories, and no one in the science community has cared enough to really try to disprove them.

The hysteresis which is supposedly the basis of the lift, and cut theory is at best unproven by science, and at worst total hogwash.

 

[josie67]

The thing I don't like about the multiblade theory, is that if the first blade actually pulls the hair up a little bit so the second blade shaves it even closer, you have the cut hair come back down below the surface of the skin, and therefore you run the risk of ingrown hairs.

 

[ouch]

suedo-science

Custom title!

 

[JPDyson]

Science?? No, it's suedo-science. Gillette invented some theories, and no one in the science community has cared enough to really try to disprove them.

The hysteresis of the lift, and cut theory is at best unproven by science, and at worst total hogwash.

False, actually - an hysteresis effect (the term here loosely applied) is 100% confirmed. It's even been shown to cut hair shorter with one pass than a single blade does, all other variables equal and with sufficient speed (not to suggest a relatively fast stroke is required, but the blades do need to be moving at a speed fast enough to catch the hair before it fully retracts and rebounds).

Whether or not this is preferable is the debate.

 

[Sledgehammer39]

Science?? No, it's suedo-science. Gillette invented some theories, and no one in the science community has cared enough to really try to disprove them.

The hysteresis of the lift, and cut theory is at best unproven by science, and at worst total hogwash.

YUP... What John said.. +1+1

 

[JPDyson]

YUP... What John said.. +1+1

John is well-intentioned, and I have the utmost respect for him - but he's a tad bit off here. Not for malice's sake, I assure you - but the science of whether multi-blade systems cut closer is clinically proven. But the resulting closer shave is not necessarily a more comfortable one.

 

[michiganlover]

John is well-intentioned, and I have the utmost respect for him - but he's a tad bit off here. Not for malice's sake, I assure you - but the science of whether multi-blade systems cut closer is clinically proven. But the resulting closer shave is not necessarily a more comfortable one.

Do you have any links to these studies that show it is clinically proven? Were they sponsored by an independent firm, that was not in cahoots with Gillette?
It would make for some good reading no doubt.

Custom title!

Apparently, I can't spell, and that word is supposed to start with a P. lol.

Pseudoscience.......

 

[Elecid]

John is well-intentioned, and I have the utmost respect for him - but he's a tad bit off here. Not for malice's sake, I assure you - but the science of whether multi-blade systems cut closer is clinically proven. But the resulting closer shave is not necessarily a more comfortable one.

From a little google research, JC Terry worked for Gillette, and even went so far as to write a letter to the editor in New Scientist in the 70's defending Gillette. How can you POSSIBLY claim that it is a scientific fact without information from a non-biased source?

I'm not saying that Mr. Terry is necessarily wrong, I'm just saying that I'd like to hear other people with no connection to Gillette corroborate his claims.

 

[michiganlover]

From a little google research, JC Terry worked for Gillette, and even went so far as to write a letter to the editor in New Scientist in the 70's defending Gillette. How can you POSSIBLY claim that it is a scientific fact without information from a non-biased source?

I'm not saying that Mr. Terry is necessarily wrong, I'm just saying that I'd like to hear other people with no connection to Gillette corroborate his claims.

Oh...that stinks of bad science, overfilling with conflict of interest, and great potential for a twisting of the facts.

Sorry, but you need a non-biased independent source in order to prove something is scientific fact, which is why I made my original post: at best unproven theories, and at worst total hogwash.

 

[Sharpj74]

The OP provides good information, thank you. Gillette (& probably Shick) cartridge systems have always worked ridiculously well for me. I've always kept a Sensor on hand, & recently on business I forgot to pack my Fatboy (which is my travel razor) so I bought the Fusion Proglide Power from the local CVS. I've been DE Shaving for quite sometime, and am super confident in my skill. However, using my travel kit (sans razor) which consists of a Tweezerman badger brush & ToBS cream, the Fusion gave me the closest, most comfortable & long lasting shave I've ever had. Not half as pretty as my Mhule Pinsel R41, not the workhorse of my '46 SS but cost of blades aside, the effectiveness of the technology of the Fusion is undeniable. Does that mean I stop DE shaving, no. It does mean that I've dodging a great razor for the sake of being elitist, not my first chartacter flaw and certainly not my last. But I now have a new razor in my rotation. Bring on the flames, all.

 

[luvmysuper]

The OP provides good information, thank you. Gillette (& probably Shick) cartridge systems have always worked ridiculously well for me. I've always kept a Sensor on hand, & recently on business I forgot to pack my Fatboy (which is my travel razor) so I bought the Fusion Proglide Power from the local CVS. I've been DE Shaving for quite sometime, and am super confident in my skill. However, using my travel kit (sans razor) which consists of a Tweezerman badger brush & ToBS cream, the Fusion gave me the closest, most comfortable & long lasting shave I've ever had. Not half as pretty as my Mhule Pinsel R41, not the workhorse of my '46 SS but cost of blades aside, the effectiveness of the technology of the Fusion is undeniable. Does that mean I stop DE shaving, no. It does mean that I've dodging a great razor for the sake of being elitist, not my first chartacter flaw and certainly not my last. But I now have a new razor in my rotation. Bring on the flames, all.

Very happy to hear it works for you, and you have another tool in your arsenal.
Wet Shaving is not about the razor as we all know, and clearly people get good results with different tools.
No one has any more right to admonish you about your use of a cart razor than they do about a Tech or a Merkur.

 

[JPDyson]

Be clear about what I said:

Hysteresis is a scientific observation, and is applicable primarily in the fields of physics pertaining to magnetism. If you disagree with me at this point, I would suggest you do a little cursory googling on the subject of hysteresis.

It is a statement of fact (and plainly observable) that a multi-blade system benefits from an effect which could be described as hysteresis; even if it isn't the primary or intended use of that term, it does fit. I say this because the second blade is there to perform its function while the hair is in its memory state from the previous blade's action, provided that second blade arrives in time. This is grade school science class observation, not some grand theory that requires elaborate explanation and evidence. If you are disagreement with me here, I'm not sure I can convince you. Most notably, at this point, I'm not saying anything any different from what we're told by Mark in his excellent shave tutor videos.

Now, please follow closely - you need to distinguish the two aspects of the claim to adequately judge it - I haven't seen evidence of this yet, so let me break it down:

Aspect 1: There is a scientific observation relevant to the description of how multi-blade systems function. Namely, hysteresis. As a result of remaining extended and prone from the first blade pulling the hair as it cuts, the second blade begins cutting the hair at a point which is lower that would be possible had the hair not be lifted.

Aspect 2: A multi-blade system, with effects described above, provides a better shave.

Aspect 1 is plainly observable. Aspect 2 is subject to matters of opinion, and should not be treated as a scientific claim.

 

[luvmysuper]

I think both of you guys have made your position well known.
Going back and forth about it isn't going to gain anything.

 

[Elecid]

Be clear about what I said:

Hysteresis is a scientific observation, and is applicable primarily in the fields of physics pertaining to magnetism. If you disagree with me at this point, I would suggest you do a little cursory googling on the subject of hysteresis.

It is a statement of fact (and plainly observable) that a multi-blade system benefits from an effect which could be described as hysteresis; even if it isn't the primary or intended use of that term, it does fit. I say this because the second blade is there to perform its function while the hair is in its memory state from the previous blade's action, provided that second blade arrives in time. This is grade school science class observation, not some grand theory that requires elaborate explanation and evidence. If you are disagreement with me here, I'm not sure I can convince you. Most notably, at this point, I'm not saying anything any different from what we're told by Mark in his excellent shave tutor videos.

Now, please follow closely - you need to distinguish the two aspects of the claim to adequately judge it - I haven't seen evidence of this yet, so let me break it down:

Aspect 1: There is a scientific observation relevant to the description of how multi-blade systems function. Namely, hysteresis. As a result of remaining extended and prone from the first blade pulling the hair as it cuts, the second blade begins cutting the hair at a point which is lower that would be possible had the hair not be lifted.

Aspect 2: A multi-blade system, with effects described above, provides a better shave.

Aspect 1 is plainly observable. Aspect 2 is subject to matters of opinion, and should not be treated as a scientific claim.

Simply because the scientific principles behind the explanation are sound does not mean that multi-bladed razors function as described in reality. In reality, other factors may change the theoretical blank slate which, like the advertisements, focus on an individual hair's reaction to a double blade. Shaving cream, hair thickness, razor angle, hair clogging, initial hair angle in relation to the blade, speed, etc... all might prevent the intended effect from occuring, or even from occuring for ALL hairs in question.

There are simply too many unaccounted for variables for the conclusion that the shave is closer to follow from your premises.

This is completely ignoring the fact that the credibility of the expert cited is in question.

 

[bradyarz]

i always hated the wires between the blades. it seemed they attracted my hair rather than kept the razor clean. on one occasion the aforementioned "anti-clog" wires got so gunked up i had to pitch the cartridge after less than one full pass.

 

[DavyRay]

Mr. JPDyson,

I completely get what you are saying about what has been proven (or not). I think the question is whether we believe the claimed results in the absence of peer-reviewed studies.

 

[JPDyson]

I think both of you guys have made your position well known.
Going back and forth about it isn't going to gain anything.

Thank you for tempering the discussion; however, I thought we were precisely on-topic in discussing exactly what was being claimed, and whether or not it was scientifically relevant.

 

[JPDyson]

Simply because the scientific principles behind the explanation are sound does not mean that multi-bladed razors function as described in reality. In reality, other factors may change the theoretical blank slate which, like the advertisements, focus on an individual hair's reaction to a double blade. Shaving cream, hair thickness, razor angle, hair clogging, initial hair angle in relation to the blade, speed, etc... all might prevent the intended effect from occuring, or even from occuring for ALL hairs in question.

There are simply too many unaccounted for variables for the conclusion that the shave is closer to follow from your premises.

This is completely ignoring the fact that the credibility of the expert cited is in question.

Elecid, you and I are in agreement. Recall that I said "all other variables equal" and completely avoided relying on outside sources.

I've sufficiently belabored by points, as Phil pointed out, so I'm finished. I hope you all find what works for you.

 

[Drubbing]

Pulling up that study, it does appear inofrmation within was derived from Gillette. If the author worked there as well, then that only confirms the less rigourous nature of the article.

That said, a cart has always shaved me closer. Personally, I believe it's because of the pivoting blade rather than the number of them, because the 2 blade Excel provided me with the exact same shave a M3 did/does.

I found the Fusion only worse purely by design; it's too damn big to work with.

Love to see scientists going at it. Get a hundred in a room, you get 500 opinions, all opposing each others minutiae. It's like Congress, only with less people asleep.