Fact or Fiction: Blades “Get Sharper” After their First Use?

[luvmysuper]

So, if the first shave (or corking for those that do it) is essentially wearing down the coating on the blades (PTFE, maybe the platinum or other exotic metal, etc.), and the blade then is "sharper" and/or "smoother" as its keen edge is now exposed, then really what is the point of putting on the coating in the first place? Marketing? Assuming the blade isn't carbon steel but stainless, the chances of it rusting (in most cases) isn't great. Or am I totally missing something here?

Maybe a less efficient factory process on some blade brands more than others in the coating process.
I've used coated blades that were good from the first go, and some that took a shave or a light run across a cork to give a smooth comfortable shave.
In the end, for me at least, the why is less important than the is. I just use blades I don't have to mess with.

 

[Goblin]

what is the point of putting on the coating in the first place?

Guys who have shaved with vintage blades from the days before PTFE coatings have said the shaves are rough as anything. The other coatings are supposed to improve edge retention.

So the PTFE coatings on most blades are there to make the blade smoother, but the coating itself can be “lumpy” and also requires a bit of smoothing out from the initial shaving strokes for the blade to reach its maximum smoothness...maybe?

 

[abies]

Option 3 is my impression: "blades don't get sharper after their first use, but they can feel smoother".

I would be interested in a compelling scientific or empirical demonstration that blades can get smoother, because I'm open to being convinced but I think most of the time they just get smoother.

For what it's worth I think in general people often confuse sharpness and smoothness, or overlook one when focusing on the other. I don't think they're the same, you can have sharp nonsmooth blades, duller smooth blades, duller nonsmooth blades, and sharp smooth blades. I'd rather have a duller smooth blade, for instance, than a sharper nonsmooth blade, but sometimes I feel a bit lonely in that.

 

[pixelrebel]

RefinedShave uses a controlled method for measuring incremental sharpness. GSB, for example, got quantifiably sharper between successive shaves.

 

[Alex Jr]

I guess what I was trying to articulate (badly) was that maybe the process of “tidying up” the PTFE behind the edge equates to more sharpness as measured by a machine that can only measure sharpness; but my epidermis, which measures a lot of different things with somewhat less precision, simply interprets this as the blade smoothing out.

Meanwhile, even before that “smoothing out” is complete the edge is probably starting to take damage and deteriorate.

I guess what we need is a series of SEM images showing a blade after 1 pass, 2 passes, 3 passes, etc. It would be fascinating to see what is really happening.

I agree on the smoothing out. Sometimes we feel smoothness as sharpness.

For me this subject can be approached from both ends. Would a naked edge (factory setting - no coating) get sharper when in contact with an object? Of course not, it only degrades, like a straight razor.

But once again quoting @T Bone, are you considering the coating as part of the blade and honing process? If you are, how does it affect the cutting power after the first use?

If you can conclude that the cutting power of a blade increases as the coating wears off then it can be said that it is in fact sharper.

That‘s my take on it, but according to my wife I’m often wrong so keep that in mind…

 

[Submariner]

Feel vs Real!!!! While it may "feel" sharper, in reality your face isn't going to sharpen a blade.

 

[pixelrebel]

So, silly question for OP: Define "blade."

 

[Goblin]

RefinedShave uses a controlled method for measuring incremental sharpness. GSB, for example, got quantifiably sharper between successive shaves.

The numbers don't lie, but at the same time, they do they disagree with my own experience and it looks like I am not alone, which is mostly what I was curious about. So far, most poll respondents seem to agree that blades don't get perceptibly sharper, but can perhaps get smoother.

I agree on the smoothing out. Sometimes we feel smoothness as sharpness.

And possibly the reverse is true as well.

If you can conclude that the cutting power of a blade increases as the coating wears off then it can be said that it is in fact sharper.

That's true, but I still wonder how the guy at refinedshave is concluding that some blades are still getting sharper after two uses (which he says are actually equivalent to 4 or 5 "regular shaves" because he shaves his head as well) when a lot of us would have thrown that blade out several shaves earlier because of the perception it was no longer sharp enough?

I guess what I really wanted to discover, and what the poll results are showing, is that the idea that "blades get sharper after the first shave" isn't some universal truth and I am far from being the only person who doesn't agree with it. I think the refinedshave data is partly responsible for "normalising" this viewpoint, but in fact, it seems like those of us who disagree with it are actually the majority!

Now we just need a member of the Excalibur Club to turn up and explain why we are wrong!

 

[psfred]

Gillette figured out in the 1950's that blade "feel", or the perception of sharpness and the actual edge acuity were not closely related. What a human feels when using a razor blade is the pull of the blade on the hairs as they are cut, and that sensation is very much related to how the hair adheres to the blade or drags on it due to surface texture, not how acute the actual shaving edge is. That is why they started coating blades, and rapidly moved to using PTFE as it's the slickest coating. Also why a lot of people prefer chrome/platinum coated blades -- less friction.

PTFE wears off a blade in a few shaves, strictly dependent upon the cross section of the hairs being cut. It will wear faster with a dense, wiry beard and slower with fine hair or less dense beards. Pure physics. Chrome and platinum are much harder and last longer, and the lower drag also reduces blade damage I suspect.

The same is true if you shave with the blade above the skin or with any angle that is quite divergent from the "ideal" cutting angle, and has nothing at all to do with the actual edge sharpness.

I would not be surprised if the coatings on the blade cause a little more drag right out of the wrapper and less as they wear a little, which explains why "corking" a blade makes it feel sharper to someone. The opposite happens when the PTFE wears off, more drag on the less slick blade makes it feel "duller" even though it's not.

I find that blades feel less sharp after a few shaves, but then don't change until they refuse to cut hair any more. Later shaves are better as the blade is less "slick" and I can control the blade contact better. Improved technique for me makes blades last a lot longer, that "is there really a blade in here" sensation is just the PTFE, not the edge.

 

[Lockback]

Smoother, not sharper. Sometimes.
And sometimes, just duller.

 

[pixelrebel]

I'm still very green at this, so, grain of salt...but, my understanding of "smooth" is that a blade is less likely to bite, scratch or leave behind undue irritation. "Sharpness" for me is how easily can it slice hair (regardless of what it does to my face). By those definitions, I would say GSB gets sharper in subsequent shaves, since the first pass of the first shave typically tugs and catches the hair.

 

[Alex Jr]

but can perhaps get smoother.

So isn’t it possible that this “smoothness“ is directly related to the sharpness numbers shown on the website? Without a scientific analysis isn’t “smoothness “ a subjective concept?

but I still wonder how the guy at refinedshave is concluding that some blades are still getting sharper after two uses

With measuring equipment and mathematical method.

isn't some universal truth and I am far from being the only person who doesn't agree with it. I think the refinedshave data is partly responsible for "normalising" this viewpoint, but in fact, it seems like those of us who disagree with it are actually the majority!

There’s no universal truth. It’s just a guy with an engineering background that decided to use specific equipment to measure something highly subjective.

Remember that not everyone here is necessarily familiar with that website or took the time to read it.

Again, I’m not saying there’s one truth and that’s it. But I can’t dispute the fact that while some are talking about “feel” there’s actually fine measured data available online.

I work in aviation, I like numbers, measurements, calculations, objective data and we learn to trust our instruments. Sorry.

Have some great shaves sir!

 

[Ron R]

It depends on the coatings used with blade, I have Polsilver super iridium and the first shave seems a little rough because iridium is a hard metal (oxide?), I will cork it sometimes and it smooths out the blade feel. Coatings are used to strengthen the edge mostly, but PTFE or Teflon coated blades are coated to smooth the shave edge. So first shave might feel sharp because coating is still mostly on the edge but as the coating wears off a little it exposes the true blade edge more and it usually feels sharper on second shave are my thoughts.
It is true a knife edge uncoated should slowly deteriorate though use where a titanium nitrite (oxides) edge will hold a edge for a lot longer.
When I machined steels as a Machinist we had different carbides with different coatings that would hold up a lot better than ones with out coatings.
We had a person that set up the Saint Petersburg plant machinery for Gillette(P&G) here on B&B years ago and he helped explain the sputtering machines that applied the coatings to the razor blade edges & what the coatings did to the edge(razor blade science).

Stumped by Sputtered

Greetings, I have just pick up a couple new packs and am confused by the new technology mentioned on the blade's package. Sputtered? Does anybody out there know the benefits of sputtering a blade? and how, for example would a sputtered blade compare to a "non" sputtered blade. Maybe it means...

www.badgerandblade.com

Have some great shaves!

 

[psfred]

According to the web sites I've seen of blade manufacturers (when I was looking for shave suitable three hole 0.020" blades) the very thin layers of platinum and chromium on edges are to reduce friction and extend blade edge life. Not enough platinum or chrome on there to "harden" the edge particularly. Synthetic amorphous diamond, ceramic coatings, and PTFE all do the same thing but PTFE wears off quickly.

The metals, and possibly the diamond, are deposited on the blade by electron impact "sputtering" -- in a vacuum chamber with a very small amount or argon (or nitrogen for nitriding) an electrical charge is applied between the item being coated and a "target" of platinum, chromium, or whatever else it being "sputtered" and the impact of the electrons flowing from the item to the target causes atoms of the target to "fly" onto the item since they are postively charged after electron impact. This allows very thin coatings -- literally atoms deep -- to form. I did this in graduate school for scanning electron microscopy, the items I was looking at had to be electrically conductive so we put a few atoms thick coatings of platinum/palladium on them as I remember. Great fun to watch them turn from white to silvery in the pink glow of the ionized argon.

Diamond, platinum, ceramic, and chrome all wear better than fine carbide stainless steel, so wear is reduced along with friction. None of them will help with deformation of the edge though. Poor angle technique causing high localized side pressure on the edge will still bend the stainless steel.

 

[Goblin]

So isn’t it possible that this “smoothness“ is directly related to the sharpness numbers shown on the website?

That's pretty much what I have been saying - what is being measured as sharpness is experienced as smoothness, at least in comparison to when the blade is fresh out of the pack. However, I think that @psfred probably gets closer to explaining what might actually be going on with this:

Gillette figured out in the 1950's that blade "feel", or the perception of sharpness and the actual edge acuity were not closely related. What a human feels when using a razor blade is the pull of the blade on the hairs as they are cut, and that sensation is very much related to how the hair adheres to the blade or drags on it due to surface texture, not how acute the actual shaving edge is. That is why they started coating blades, and rapidly moved to using PTFE as it's the slickest coating.

So, a machine is measuring the blade as being sharper, because the PTFE is being smoothed out and / or worn away to expose the edge. However, because that PTFE is wearing away, the blade is becoming more "sticky" and prone to adhereing to the facets it creates as it severes the whiskers, which makes it feel less sharp to the user.

This explains how we can have contradictory sets of data: quantitative data from a guy with a measuring device, which says the blade is getting sharper; and qualitative data from the members here whose experience says that the blade does not get sharper. Turns out, both can be correct without being mutually exclusive!

 

[luvmysuper]

So, a machine is measuring the blade as being sharper, because the PTFE is being smoothed out and / or worn away to expose the edge.

This.

No CUTTING edge gets sharper after cutting.
The only thing that makes a cutting edge sharper after use, is sharpening it with an object that abrades away the steel to create a new cutting edge.

 

[Alex Jr]

So, a machine is measuring the blade as being sharper, because the PTFE is being smoothed out and / or worn away to expose the edge. However, because that PTFE is wearing away, the blade is becoming more "sticky" and prone to adhereing to the facets it creates as it severes the whiskers, which makes it feel less sharp to the user.

This explains how we can have contradictory sets of data: quantitative data from a guy with a measuring device, which says the blade is getting sharper; and qualitative data from the members here whose experience says that the blade does not get sharper. Turns out, both can be correct without being mutually exclusive!

Interesting conclusion and I can totally agree with that.

The BIC blade in my view would be a great sample for the subject of this thread. I can feel it increase the cutting power significantly as the initial coating wears off, more than any other blade. While others decline, bics seem to go up and up as you shave. I’d assume there must be a heavy and persistent coating in it.

Again, very nice thread sir. Now I think we’d better get the hell out before @Quaznoid comes here and call us all crazy.

Back to my pipe

 

[BradWorld]

Since most of us are not using expensive scientific equipment to measure actual sharpness, or edge geometry, we are talking about perception here. For me, there are blades that absolutely “feel” sharper on the second shave. If this is resulting from the coating scrubbing off the edge, so be it. The perception is that the blade is sharper on shave two. The blade feels sharper to me, and not necessarily smoother. Those two things are not the same. And not mutually exclusive.

 

[Quaznoid]

Nah, you’re not crazy. Blades can get smoother or change in some undefinable way but they can’t get sharper. I’ll continue to use Lord family blades for 3 shaves and that’s it. If, for some reason, they should become unavailable, I’d go back to the trusty Lab Blue.

 

[Alex Jr]

Nah, you’re not crazy. Blades can get smoother or change in some undefinable way but they can’t get sharper. I’ll continue to use Lord family blades for 3 shaves and that’s it. If, for some reason, they should become unavailable, I’d go back to the trusty Lab Blue.

First shave tomorrow with the lord platinum “diamond edge” (black package).

It’ll be interesting to see if it’s the same as the white platinum or a different blade.

Praise the lord!