It's smooth, but it ain't sharp!

[AshleyC]

Am I the only one who finds this distinction baffling?

Or the declaration that a blade is sharp...but not all that smooth?

How can a not so sharp blade be "smooth"? Man...it smoothly glided across my face as the blade seemed to be the equivalent of a facial bikini wax!

I really don't get the distinction.

 

[cgr86]

Am I the only one who finds this distinction baffling?

Or the declaration that a blade is sharp...but not all that smooth?

How can a not so sharp blade be "smooth"? Man...it smoothly glided across my face as the blade seemed to be the equivalent of a facial bikini wax!

I really don't get the distinction.

Try a feather in your favorite razor then try a Gillette Silver Blue. I’m willing to bet you’d know exactly how one can be sharp but not smooth.

 

[AshleyC]

I've tried both...I think. Oh...the Gillette was a Nacet, not a Blue. I know Feathers well enough.

This is a concept I will have to devote some thinking to.

 

[Bogeyman]

There isn't a difference. "Sharp" is actually smooth.

 

[FireDragon76]

I assume smooth blades have less roughness along the bevel, and better coatings.

 

[naughtilus]

Efficient enough to cut your stubble but not exfoliate every skin bump possible is the golden middle ground.

 

[AshleyC]

Efficient enough to cut your stubble but not exfoliate every skin bump possible is the golden middle ground.

So...Astra Greens.

Why do we bother with anything else?

 

[Bogeyman]

So...Astra Greens.

Why do we bother with anything else?

Because there are better blades.

 

[YouToo]

I think the sharp vs smooth thing happens on a microscopic level, depending on the roughness/smoothness of the blade edge (which in turn depends on how it was made) and the type of skin and beard. I think sharpologist had some article a while ago about different blades under a microscope, revealing lots of differences between the brands. Differences our skin and beard might notice and we feel it, but we can't really actually see it other than the result afterwards.

 

[Bogeyman]

A little scientific info:

...It should be noted that the thinner the PTFE coating becomes on blade edges, the lower the cutting force (assuming the coating is uniform). While this is generally desirable as mentioned above, too thin PTFE coatings on blade edges can give rise to poor coverage and low wear resistance due to intrinsic properties of the PTFE material. Alternatively, a too thick PTFE coating may produce very high initial cutting forces, which generally may lead to more drag, pull, and tug, eventually losing cutting efficiency and subsequently shaving comfort. Thus, there is a technical challenge to balance the attributes of the polymer material with obtaining the thinnest coating possible to provide improved shaving attributes...

US Patent for Formation of thin uniform coatings on blade edges using isostatic press Patent (Patent # 10,315,319 issued June 11, 2019) - Justia Patents Search

The invention discloses isostatic-pressing (IP) applied to polymer (e.g., PTFE) coated razor blade edges to produce thin, dense, and uniform blade edges which in turn exhibit low initial cutting forces correlating with a more comfortable shaves. The isostatic press utilized may be a hot...

patents.justia.com

 

[weizemanner]

Am I the only one who finds this distinction baffling?

Or the declaration that a blade is sharp...but not all that smooth?

How can a not so sharp blade be "smooth"? Man...it smoothly glided across my face as the blade seemed to be the equivalent of a facial bikini wax!

I really don't get the distinction.

Some of it has to do with coatings, some from the grit the blade is honed with maybe a bit from the angle of the bevel and how much the blade flexes. Some of these things are also controlled by the razor which is why some blades work great for one person in one razor but are terrible with the same face but a different razor.

If you look at a razor blade under a microscope, the blade has scratches in it that make little teeth on the edge and get smaller with finer grit hones, just as you would expect. At about 3000 grit, you can make a razor that will cut hair just fine, but those teeth would be scratching your face. Now with too high of a polish you can get the opposite problem, the teeth aren't big enough to cut into the hair efficiently. Coatings make it more complicated because there are some that can smooth out a rough blade edge and some can make the blade seem sharper.

Feather blades to me are extremely sharp, there is never a tug or anything like that, but they leave my face raw after 2 passes and give me nicks and cuts frequently.

Notoriously less sharp blades like derbys can pull on my beard if I am not slanting or using the gillette slide. But the tug is only the force of the razor's weight, even pulling a single hair with what, 2oz? shouldn't hurt that much. And the smoothness of the edge doesn't scratch my face.

I find that I can go over an area that I want closer many times, sometimes 4 or 5 passes with a Derby, whereas the second pass on a Feather is max.

For some people the sharpness is more important than the smoothness. Some are just the opposite.

Like anything else, most people are going to fall somewhere in the middle, which is why there are so many choices out there. Astra and lab blue are some of the most popular out there because they are a combination of medum sharpness and good smoothness.

 

[naughtilus]

So...Astra Greens.

Why do we bother with anything else?

GSB, GP, PSI, DP also great options. I call them the Aristotelian blades.

 

[BigJ]

Some of it has to do with coatings, some from the grit the blade is honed with maybe a bit from the angle of the bevel and how much the blade flexes. Some of these things are also controlled by the razor which is why some blades work great for one person in one razor but are terrible with the same face but a different razor.

If you look at a razor blade under a microscope, the blade has scratches in it that make little teeth on the edge and get smaller with finer grit hones, just as you would expect. At about 3000 grit, you can make a razor that will cut hair just fine, but those teeth would be scratching your face. Now with too high of a polish you can get the opposite problem, the teeth aren't big enough to cut into the hair efficiently. Coatings make it more complicated because there are some that can smooth out a rough blade edge and some can make the blade seem sharper.

Feather blades to me are extremely sharp, there is never a tug or anything like that, but they leave my face raw after 2 passes and give me nicks and cuts frequently.

Notoriously less sharp blades like derbys can pull on my beard if I am not slanting or using the gillette slide. But the tug is only the force of the razor's weight, even pulling a single hair with what, 2oz? shouldn't hurt that much. And the smoothness of the edge doesn't scratch my face.

I find that I can go over an area that I want closer many times, sometimes 4 or 5 passes with a Derby, whereas the second pass on a Feather is max.

For some people the sharpness is more important than the smoothness. Some are just the opposite.

Like anything else, most people are going to fall somewhere in the middle, which is why there are so many choices out there. Astra and lab blue are some of the most popular out there because they are a combination of medum sharpness and good smoothness.

Good explanation of some confusing terminology!

I am definitely in the middle on this one: Feathers are just too sharp but not smooth enough for me.

 

[geneaut]

Sometimes I equate sharp with efficient, and smooth with comfort.

I like Ladas, Red IPs, Astras ( both flavors ) and Rapira Supersteels since I rarely cut myself with them and they feel good on the face. No tugging or skipping. However, it takes more passes to get the same result that a GSB or a Polsilver give me in less work. All are 'smooth' to me though, but in my head I think the GSBs and Polsilvers are sharper.

I think some blades we say are smooth are actually insanely sharp so they don't tug or skip. Some 'sharp' blades don't seem 'smooth' to me since they also give me a strange face feel ( the new Dorco Primes feel sharp but I get a tingle from them I don't with many blades ). Some are actually just smooth for other reasons ( I imagine grind/hone matching up well with our particular facial hair profile ).

So I have no concrete real definition of the terms and I imagine some others don't either. A lot of it is confirmation bias anyway

 

[razorhead63]

Try a feather in your favorite razor then try a Gillette Silver Blue. I’m willing to bet you’d know exactly how one can be sharp but not smooth.

Good suggestion!

 

[Macduff]

I think that at least in my opinion “smooth” would be a combo of how it feels cutting through the hair as well as the the end result (weepers, burn, etc.) I’ve found very sharp blades that feel awful shaving with and dullish blades that are smooth as butter. I really think @weizemanner nailed it with his explanation. The grind and coating have everything to do with both the face feel and end result. Sharp it may be, but perhaps not smooth. But i think we all instantly recognize a dull blade.