Sharp makes sense, but what is smooth?

[spacemonkey42]

Blade sharpness makes sense. One could measure it in different ways and it could be quantified. It is an intrinsic trait of a blade.

Smoothness on the other hand seems anecdotal. I don't think it could be appropriately measured or quantified. While we all have impressions of smoothness, I suspect it is heavily influenced by the razor and soap we are using and our technique.

Discussions of blades here have very differing impressions of smoothness. On the other hand, while there isn't complete agreement, in general sharpness is much more agreed upon. The opposite of sharp is dull, of course. What is the opposite of smooth? Is it rough? I've heard some here say that less-sharp equals smooth, so is it dull? While we all have our own impressions of smooth, and that is fine for each individual, I think it is about a lot more than just the blade and isn't the same from person to person. Thus smoothness is not an intrinsic trait of a blade.

Likewise, I also don't think aggressive is a trait of a blade. Blades are sharp or dull. Razors are designed to put the blade in a more or less aggressive position (angle, exposure, gap, etc.).

I humbly submit these thoughts for discussion.

 

[Eric_75]

Discussions of blades here have very differing impressions of smoothness.

Bic Chrome Platinum come to mind for me. Some describe them as sharp but not exactly smooth. I find them to be both but I've only used them in a King C. Gillette and a Gillette Heritage and they work great in both of those razors for me. Sharp and smooth. Looking forward to the replies in this thread.

 

[spacemonkey42]

Voskhod come to mind for me. Few call them very sharp and I agree with that. Many call them smooth and they have been quite rough/tuggy/dull/bad for my whiskers in the couple of razors I have tried them in.

 

[T Bone]

Yeah I’m not sure what makes a blade “smooth” either. I don’t find it a very useful term tbh, even though I’ve used it myself. I guess I’ve understood it (and used it) as a catch-all for positive results from a blade besides quantifiable sharpness. Did it tug? Did it cut my face more easily than my whiskers? Did it cause irritation? If not, then it’s smooth. Seems much more YMMV than “sharp”. But what do I know. If there’s a real definition for “smooth”, I’d love to hear it.

 

[LRod]

And then comes this detour:
The "smooth" factor in a blade can also change when used on a different razor. I've had blades that feel really smooth in one and not so smooth on another.
The "sharp" factor always remains the same. A blade is either sharp (or not) on any razor you throw it on.

I look forward to the 100+ pages that this thread will become

 

[D4PPZ]

Whether a blade is sharp is something that can be felt on the skin, some blades are more "bitey" than others. Smoothness is whether or not it glides over your skin "smoothly" or whether it tugs its way through the hair. If it's tuggy, you'll have to use more pressure to get through the hair, and if it's also sharp, this can cause irritation and nicks. "Smooth" is necessary while sharp is situational. If it's sharp and tuggy, it's a bad blade. If it's dull and tuggy, it's a butter knife. If it's dull and smooth it can work in some razors, with smooth and at least mid-sharpness being ideal.

 

[Alex Jr]

BIC. Try it and you’ll know.

 

[spacemonkey42]

And then comes this detour:
The "smooth" factor in a blade can also change when used on a different razor. I've had blades that feel really smooth in one and not so smooth on another.
The "sharp" factor always remains the same. A blade is either sharp (or not) on any razor you throw it on.

That isn't a detour at all @LRod, we're making the same point, that sharp is real and inherent to the blade, and smooth is situational.

 

[LRod]

That isn't a detour @LRod, that's the same point, that sharp is real and inherent to the blade, and smooth is situational.

When I read and responded to your post I didn't see any mention of razors being part of the equation. I do see it now at the end of your post. I missed it the first time. So I was adding in the "razor" factor when I had just initially read about the "blade factor. My mistake!

 

[velocityboy]

A serrated knife can be sharp but not smooth. A butter knife can be smooth but not sharp. A great razor blade combines these two not necessarily related characteristics.

 

[Yuritau]

Everything to do with blade comfort comes down to two main factors: edge geometry and how it's applied to the skin.

Edge geometry includes blade thickness, material rigidity, grind angle, single bevel vs compound bevel, and edge polish. Change any one factor on that list and the blade will feel different. Sharpness is entirely determined by the combination of these factors. These factors also determine how resilient the edge is and thus how long it will last. The geometry for maximum sharpness likely will not work out to be the most resilient geometry.

How the blade is applied to the skin includes how rigidly it's clamped in a razor, what angle it's presented at to the skin, how much blade is exposed, coatings on the blade edge, the quality of the lather, and the technique used to wield the razor. This is why the same blade can feel very different in different razors.

Sharpness you can measure with a edge tester, and if you know what you're about, you can design the edge geometry to achieve a certain level of sharpness. Also, there are no dull DE shaving blades, at least not outside of QA/QC mishaps. If you want to experience a dull DE blade, try shaving with the ones intended for scraper use that you can often find in the paint section of the local hardware store.

Perceived smoothness comes from all these factors working together and pretty much always retains some subjectivity. Even simple changes like switching from riding the guard to riding the cap can change how smooth a blade feels. If you put the time in and keep notes, you can even develop a list of blades that work the best for you and per razor (even per different base plate or adjustment setting).

 

[markmc]

The only quantifiable trait that comes to mind is the coating. For instance, I find platinum coated blades smooth. Stainless blades with no coating, not as much. It also could be marketing and I’ve experienced the placebo effect.

 

[Herrenberg]

Despite this being a DE thread, I feel compelled to intrude with some SR lore, because SR shavers with a lot of finishing stone experience are extremely familiar with sharp vs. smooth. It's a real thing, and an intrinsic property of the sharpened blade. If you wanted to measure it, microscope photos of the edge would be best.

Hard to think of it as mystical and mysterious when you see the jaggedness, or lack thereof, of the edge.

 

[Alum of Potash]

I agree with Herrenberg above. With either a straight or a DE blade, I think it is useful to think of the opposite of "smooth" as being "harsh." A sharp razor blade can be smooth or harsh. Sometimes when it becomes too "sharp" the result is harshness, leading to unexplained weepers, an uncomfortable feel after the shave, etc. When all the stars are aligned, there is smoothness. No weepers, no burn in applying the alum block, a great feel after the shave.

 

[Zora]

I believe the smoothness of the grind (after/past the immediate blade edge) and the coating on the blade play a big part in the “smoothness” aspect, seperate from the edge sharpness.

 

[BigJ]

Everything to do with blade comfort comes down to two main factors: edge geometry and how it's applied to the skin.

Edge geometry includes blade thickness, material rigidity, grind angle, single bevel vs compound bevel, and edge polish. Change any one factor on that list and the blade will feel different. Sharpness is entirely determined by the combination of these factors. These factors also determine how resilient the edge is and thus how long it will last. The geometry for maximum sharpness likely will not work out to be the most resilient geometry.

How the blade is applied to the skin includes how rigidly it's clamped in a razor, what angle it's presented at to the skin, how much blade is exposed, coatings on the blade edge, the quality of the lather, and the technique used to wield the razor. This is why the same blade can feel very different in different razors.

Sharpness you can measure with a edge tester, and if you know what you're about, you can design the edge geometry to achieve a certain level of sharpness. Also, there are no dull DE shaving blades, at least not outside of QA/QC mishaps. If you want to experience a dull DE blade, try shaving with the ones intended for scraper use that you can often find in the paint section of the local hardware store.

Perceived smoothness comes from all these factors working together and pretty much always retains some subjectivity. Even simple changes like switching from riding the guard to riding the cap can change how smooth a blade feels. If you put the time in and keep notes, you can even develop a list of blades that work the best for you and per razor (even per different base plate or adjustment setting).

Great explanation!

For me, Feather blades generally are very sharp but not especially smooth. The exception is when you put a Feather blade in an AS/D2, then I get very nice shaves!!

 

[Inverted]

I agree with this. In fact, I will take it a step further and say the blade can't even come across as smooth or rough. There is so little contact between the blade and the skin that I really don't understand from a technical level, how a blade contributes to the smoothness of the shave. Now if you are tugging and pulling, that would indicate that the blade isn't sharp. The blade's only job is to cut the hair. The razor's job is to angle the blade, expose the blade, and provide a surface to safely move the blade across your face. There are so many more variables to the overall shave in the razor (material, finish of the head, shape, blade exposure, gap, solid bar, open comb etc., razor weight and probably so much more I am missing). A smooth shave would be a sharp blade by every metric and account. The less effort it takes to cut the hair and glide across, the "smoother" the shave would appear.

 

[Ron R]

To me a very sharp blade will tend to dig in more and shear any blemishes off quickly where a blade with not so much sharpness tends cut whiskers easily still + with the right coatings seems to glance better on the soaped up wet lather skin with less chance of digging in. Sharp & smooth blade has more a balanced physically attributes that just give the right feeling when used in almost any razor it seems like the Gillette silver blue blade.

 

[Space_Cadet]

Can smoothness or aggressiveness or whatever be "measured or quantified" in all other cases but blades?

 

[Ratso]

Smooth to me is comfortable. A perfect example for me is my Dart razor. I wanted to like my Dart, but could never get a smooth/comfortable shave. Close was no problem. The shaves had to much blade feel( another term that needs defining?) and I felt the need to really be careful. I tried quite a few blades with this razor and finally hit a decent blade for me. The German Wilkinson on its second or third use.