Thread: Sharpness of Straight vs DE & SE

A thought just occured to me about the coating, are we not also putting a coating on the straight razor edge when we strop???

Originally Posted by Seraphim

I used to feel as you do. That all the "fuss" about how long lasting a straight shave was compared to even a good DE shave was a bunch of hype/wishful thinking.

But after a while, the closeness of a straight shave really does significantly exceed that of a DE.

I also have a Futur. It is an awesome razor, especially when loaded with a Feather!





I haven't used it since July......

You can have my Futur when you pry it out o my cold, dead hands...



As for coating...Glenn, the way I understand coating of DE blades is, the coating seeps into all the little serrations that remain in steel after grinding and polishing, kind of filling it in like spackle. The platinum/ceramic (in the case of Feathers) covers those serrations so it makes a smoother shave. I guess good stropping on good steel has a similar smoothing effect in straightening out the serrations, but they're still there, aren't they? (I'm speaking with very little knowledge of straights, except what I've picked up reading this forum and the Wiki religiously for the past week or so...I'm genuinely curious, not trying to be argumentative.)

Originally Posted by gssixgun

A thought just occured to me about the coating, are we not also putting a coating on the straight razor edge when we strop???

I've always suspected that stropping is our way of applying the secondary bevel. You'll notice a big difference in shave quality when you truely learn how to strop an edge. This secondary bevel is applied with a slight deflection that occurs natuarally with a hanging strop.

Originally Posted by jcw122

I'm kinda interested in an idea I just got. I remember reading a thread about possibly making ceramic straight blades, but that it would be a horrible idea because it would be TOO sharp, to the point where it would be hard to shave with and not cut into your skin.

So this makes me wonder if it really matters if DE is sharper, because that might not necessarily mean better results or less irritation.

Yeah, some nutjob here at SRP is already trying that...

Originally Posted by JimR

You can have my Futur when you pry it out o my cold, dead hands...



As for coating...Glenn, the way I understand coating of DE blades is, the coating seeps into all the little serrations that remain in steel after grinding and polishing, kind of filling it in like spackle. The platinum/ceramic (in the case of Feathers) covers those serrations so it makes a smoother shave. I guess good stropping on good steel has a similar smoothing effect in straightening out the serrations, but they're still there, aren't they? (I'm speaking with very little knowledge of straights, except what I've picked up reading this forum and the Wiki religiously for the past week or so...I'm genuinely curious, not trying to be argumentative.)

I don't think that it fills in the serrations. In the pic I linked to earlier, you can see that the edge has a fair bit of structure to it. My straights are much smoother than that, but the Feather "glides" better. I think it's a coefficient of friction issue, not a physical smoothness issue.

I couldn't see any Feather pics. The straight pics are there though.

Originally Posted by gssixgun

You know I have heard this for some time now, that DE and SE blades are sharper than straights...
I have also told people numerous time to use either one, to get a feel for how the edge tests (TNT, TPT, HHT) should look and feel when learning to hone....

I have always taken this to be a true statement, until I actually bought a DE and actually used it ONCE to shave with before selling it.... (not for me)
At that time I took one of the DE blades and did what I had told people to do many times, and tried the blade tests myself... Needless to say I was not all that impressed with what I found, it passed all the tests and I still think it is a good way to learn how the tests should feel, but I would put any of my edges against those Personna edges any day of the week...
I have never even held a Feather so I could not say on that one...
That's my new 2 cents...
So from now on I will not automatically assume that machine made edges are better than hand honed straight edges, I wanna see it, and have it proved to me....

And I would put one of your edges up against a Derby Extra DE blade any day of the week, too. When I received my Glen sharpened straight, I compared it directly to a Derby Extra DE blade. I did all the usual tests, as well as a few *unusual* tests. There was no discernible difference.

To those that say that DE blades are sharper, I would counter the argument that there is a difference between ease of use and sharpness. The DE blade, and it's corresponding "safety razor" take out *alot* of the variables that can cause uncomfortable shaving; safety razors are *much* easier to just pick up and get a comfortable shave without much learning curve. If you take a straight of equivalent sharpness, given correct technique, you will get *at least* as close and comfortable shave as with the DE.

Let's say that on one day, you give a guy an adjustable safety razor with a new blade in it, set to it's least aggressive setting. Don't give him any instructions (he's never used one before), and let him get to work. he'll probably get a decent shave.

The next day, give him a straight of corresponding sharpness. Again, don't give him any instructions. Let him get to work, but make sure you have the Red Cross there to replace the lost blood.

Summary: I'd put a honemeister sharpened blade up against any machined DE blade anytime. Sharpness isn't to be confused with ease of use.

Originally Posted by elbonator

I hope mparker chimes in here as he read the Verhoven paper closer than I did. If my memory serves me right Professor Verhoven found that in terms of keenness as defined by edge thickness commercial blades and straights are virtually the same. The coatings put on commercial blades prevent them from grabbing the skin as much if at all. This suggest the possibility that greater pressure can be used which may account in some cases for perceived differences in keenness. I'm just speculating.

Unfortunately my machine crashed so I lost the verhoeven paper and the 1920's popular mechanics article but that was one of the first things Verhoeven looked at. He compared a commercial razor blade (he didn't say if it was a DE or cartridge blade) and a straight razor that was honed by a guy he knew that still shaved with a straight. Both the commercial blade and straight razor averaged 0.5 microns across the edge as measured at 3000x with an electron microscope. The other interesting thing is that Verhoeven was able to get that same 0.5 micron edge with 9 micron diamond paste, an 8000 grit waterstone, and 0.5 micron diamond and chrome oxide. The finer grits simply gave him a higher level of polish and less variation in the cutting edge width along the blade. Oh and there were no serrations at the edge at anything finer than about 800 grit. You could see the grooves going down the bevel, but the cutting edge itself was formed where the steel finally got too thin and just kind of tore off. Softer steels couldn't take quite this fine of an edge, and steels around 63 rockwell could take very slightly finer edges (0.48 or some such).

The other interesting article is an article on the Schick website titled "Making of the Modern Blade" which mentions that they put the teflon coating on the blade specifically to reduce the cutting friction, which reduces the pulling sensation and improves the sensation of sharpness. This was a good clue that the reason the finer grit hones produce a better shaving edge is because the more polished edge causes less friction when cutting through the whisker.

And finally, the 1920's popular mechanics article examined the degradation of an edge across several days of shaving, both with and without stropping. They used a 3000x optical microscope to do this, so the pictures don't have the stunning clarity of Verhoeven's electron microscope, but the results were comparable. Their photos also show the torn-looking edge for example, and they were quite surprised by the lack of serrations or teeth. But most importantly these photos show that the main cause of dulling is corrosion and not wear. The stropping action knocks off the softer corrosion, exposing the pitted steel below, then further stropping polishes the underlying steel a bit. My suspicion is that one of the reasons razors gradually get to the point where stropping doesn't help is because the bevel near the edge gets corroded and pitted enough that the cutting friction is just too high, so you need the hone to cut the steel back past the pitting. Remember the cutting edge is also slicing through the top layer of skin, so it's exposed to a pretty harsh environment for steel. I suspect this is also why vintage razors sometimes need to be honed so much before they shave well - their edges are shot through with microscopic pinholes of rust, and it's not so much that they won't hold an edge (though this also happens) as they're simply too shot through to provide a polished low-friction bevel.

Two side-effects of studying this issue are that I've become much more appreciative of aggressive use of the linen strop, and a lot less critical of guys who use pastes. They're both a means to keep that edge polished, it just depends on whether you prefer the romanticism of the 19th century linen or the efficiency of 20th century industrial abrasives.

Originally Posted by mparker762

Unfortunately my machine crashed so I lost the verhoeven paper and the 1920's popular mechanics article but that was one of the first things Verhoeven looked at. He compared a commercial razor blade (he didn't say if it was a DE or cartridge blade) and a straight razor that was honed by a guy he knew that still shaved with a straight. Both the commercial blade and straight razor averaged 0.5 microns across the edge as measured at 3000x with an electron microscope. The other interesting thing is that Verhoeven was able to get that same 0.5 micron edge with 9 micron diamond paste, an 8000 grit waterstone, and 0.5 micron diamond and chrome oxide. The finer grits simply gave him a higher level of polish and less variation in the cutting edge width along the blade. Oh and there were no serrations at the edge at anything finer than about 800 grit. You could see the grooves going down the bevel, but the cutting edge itself was formed where the steel finally got too thin and just kind of tore off. Softer steels couldn't take quite this fine of an edge, and steels around 63 rockwell could take very slightly finer edges (0.48 or some such).

The other interesting article is an article on the Schick website titled "Making of the Modern Blade" which mentions that they put the teflon coating on the blade specifically to reduce the cutting friction, which reduces the pulling sensation and improves the sensation of sharpness. This was a good clue that the reason the finer grit hones produce a better shaving edge is because the more polished edge causes less friction when cutting through the whisker.

And finally, the 1920's popular mechanics article examined the degradation of an edge across several days of shaving, both with and without stropping. They used a 3000x optical microscope to do this, so the pictures don't have the stunning clarity of Verhoeven's electron microscope, but the results were comparable. Their photos also show the torn-looking edge for example, and they were quite surprised by the lack of serrations or teeth. But most importantly these photos show that the main cause of dulling is corrosion and not wear. The stropping action knocks off the softer corrosion, exposing the pitted steel below, then further stropping polishes the underlying steel a bit. My suspicion is that one of the reasons razors gradually get to the point where stropping doesn't help is because the bevel near the edge gets corroded and pitted enough that the cutting friction is just too high, so you need the hone to cut the steel back past the pitting. Remember the cutting edge is also slicing through the top layer of skin, so it's exposed to a pretty harsh environment for steel. I suspect this is also why vintage razors sometimes need to be honed so much before they shave well - their edges are shot through with microscopic pinholes of rust, and it's not so much that they won't hold an edge (though this also happens) as they're simply too shot through to provide a polished low-friction bevel.

Two side-effects of studying this issue are that I've become much more appreciative of aggressive use of the linen strop, and a lot less critical of guys who use pastes. They're both a means to keep that edge polished, it just depends on whether you prefer the romanticism of the 19th century linen or the efficiency of 20th century industrial abrasives.

Exactly. The limit to edge sharpness is the type of steel the blade is made of. Both sharpening machine and honemeister are capable of reaching that limit.

If the best steels are only capable of a 0.5 micron edge, how sharp an edge can ceramics acheive? I know that diamond can acheive edges 1 atom thick based on an article that used a scanning tunneling microscope.