Neither of the two videos embedded in the linked press release shows any damage to the blade of the razor. They each cut out at the point that the blade has just finished slicing through a hair, while the hair is still in contact with the blade edge and obscuring our view of any hypothetical chips or defects caused by the cutting process. Bizarre.
For those interested in the SEM images and looking for more, check out this site: <a href="https://scienceofsharp.com/home/" rel="nofollow">https://scienceofsharp.com/home/</a><p>The site focuses mainly on sharpening razor blades and is full of SEM images of blades in various conditions. Very cool to see.<p>This page about burrs has some particularly cool images: <a href="https://scienceofsharp.com/2015/01/13/what-is-a-burr-part-2/" rel="nofollow">https://scienceofsharp.com/2015/01/13/what-is-a-burr-part-2/</a>
> The team’s findings may also offer clues on how to preserve a blade’s sharpness. For instance, in slicing vegetables, a chef might consider cutting straight down, rather than at an angle. And in designing longer-lasting, more chip-resistant blades, manufacturers might consider making knives from more homogenous materials.<p>I'm no knife expert, but my understanding is that today's best knives use VG-10 steel, which is designed to "chip itself to make itself sharper". So its hard, flexible, slightly more brittle than you'd expect. But these micro-chips end up sharpening the blade more often than not. There's more than one way to design a blade's metallurgy.<p>For shaving steel, it needs to be as cheap and flexible as possible, so that machines can mass produce them. High end knife-blanks cannot be punched if the steel is too hard or strong (leading to a "price cliff", where the best steels are an order of magnitude more expensive than the punchable lower-cost steels).<p>--------<p>So yes, very interesting experiment. But also consider the overall picture: chip-resistance isn't everything.
I don’t have anything useful to say other than damn I love SEM movies!<p>I bought a Celestron USB microscope. It was fascinating to look at my skin, nails, desk surface, carpet, anything. Well, at least for the 15 minutes before the device failed. I returned it and never bought a replacement. :-(<p>Has anyone had luck with a toy-ish microscope in the $200 range?
<i>The researchers have filed a provisional patent on a process to manipulate steel into a more homogenous form, in order to make longer-lasting, more chip-resistant blades.</i><p>Considering what started the whole idea of the consumables industry, a patent on making razor blades longer-lasting seems incredibly ironic.
This study should be considered along with that from metallurgist John Verhoeven, who thought the main cause of chipping is corrosion. (<a href="https://knifesteelnerds.com/2021/01/11/what-causes-razor-blades-to-dull/" rel="nofollow">https://knifesteelnerds.com/2021/01/11/what-causes-razor-bla...</a>)<p>What both these studies reveal is an absence of bending of the sharp edge, indicating that the tradition of razor stropping has no real effect.
<i>> When he analyzed the SEM images and movies taken during the cutting experiments, he found that chips did not occur when the hair was cut perpendicular to the blade. When the hair was free to bend, however, chips were more likely to occur. These chips most commonly formed in places where the blade edge met the sides of the hair strands.</i><p>Extending the life of a razor blade sounds nice, but cutting hair perpendicular to the blade means shaving against the grain, does it not? I don’t want to handle the pain of doing that on the first or second pass while the hair is still long enough (like a couple of millimeters or longer, which cannot be trimmed using a trimmer and needs a blade). But shaving against the grain gives the smoothest skin texture (at the risk of causing ingrown hair, which for me is quite rare).<p>What I’m saying is that I’d rather the blades dull and need replacement sooner than put up with the burn and pain caused by shaving against the grain from the get go. A few passes with the grain and perpendicular to the grain (sideways) helps the “against the grain pass” be less painful and provide a smoother result.<p>I’d still love a blade that lasts longer though.
> An in-situ hair cutting experiment in a scanning electron microscope, showing the chipping process. Image: Gianluca Roscioli<p>That video was oddly pleasant to watch. I admit I was expecting to see the blade become miraculously f'd up in the process, due to the rest of the article, but hair is indeed very soft and the look of that angular cut at such a scale is kind of amazing to think about.<p>(Perhaps when such microscopes hit Aliexpress we'll see this genre enter the extremely-satisfying-videos arena)
Discussed at the time:<p><i>Why shaving dulls even the sharpest of razors</i> - <a href="https://news.ycombinator.com/item?id=24075855" rel="nofollow">https://news.ycombinator.com/item?id=24075855</a> - Aug 2020 (123 comments)
I've read a ton about razors in the past decade or so, and wish more of what has been reported was covered here. This just reports that hairs microchip blades. To what extent does it matter, for example?<p>Firstly, I'd read that DE blades actually get sharper after the first shave, due to coating wearing off, then quickly dull after the third or fourth shave. Personally, I'm unsure of this finding, as I always find new blades the best cutting and in fact change my blade every other shave.<p>Secondly, it's commonplace to the point of common knowledge or folk lore that it is rusting that ruins blades, hence you should soak them in alcohol, or dry them vigorously after each shave. Is this even true?
With kitchen knives, acid in fruits, esp, is the main reason they grow dull. Rinse 'em immediately after, without fail.<p>Skin oils might be a bit of harm, too.
This explains why my shaving blade last for me very long time - I always shave in the opposite direction of hair growth, not along, so that blade always approaches hair at nearly 90 degrees.<p>if you shave along the direction of hair growth, the blade will approach hair at 15-30 degrees which causes excess wear & tear on a shaving blade.
Interesting article! However I hoped to get some recommendations, or at least “it doesn’t matter what you buy”, and maybe some comments on the performance of multi-blade razors.<p>Given that the angle of cut matters is it better to shave certain parts of the face with the grain or against?
<i>Item 1.</i> I hate sharpening knives and tools, so I wish someone would do a similar study for wood plane irons/blades (including their different steel types) versus various grinding techniques, grinding grit sizes etc.; and also explain why good old carbon steel often gives a smoother cut than do many of the harder specialized steels that have Rockwell figures which are well into the 60s—even though the fact that carbon steel dulls and blunts much more quickly than do those much harder steels?<p><i>Item 2.</i> In a somewhat oblique vein, during COVID I always wore N95/P2 masks in public and I always took extra heed to follow the instructions that came with them which read to the effect that <i>'this mask will be less effective on those with bearded faces'.</i><p>Clearly that stands to reason so the question is by how much.<p>I'm constantly bemused by the large percentage masks on bearded faces and whose wearers seem oblivious to the fact that their beards are likely rendering their masks ineffective. Especially so when I see doctors on TV who've beards and who are there specifically to proselytize the virtues of wearing masks. With their beards popping out from behind their ill-fitting masks, it seems strange to me that these highly trained medicos seem oblivious to the obvious fact that their beards are putting them at risk—not to mention that they are setting a bad example.<p>Now the issue is this: given that a clean-shaven, stubble-free face provides a better mask-to-skin seal than one with stubble, the questions are:<p>Does anyone know of whether tests have been done on N95-type masks to test the effectiveness of their mask-to-skin seals? If so, whether any significant leakage was detected at the seal and whether stubble growth throughout the day worsened said leakage (the implication being that by the afternoon/evening masks would be less effective though increasing seal leakage)?<p>The corollary of the question would be to ask if a beard stubble impedes the effectiveness of the mask-to-skin seal then at what point in the growth of a newly-forming beard (at what stubble length, etc.) does the stubble render the mask ineffective (dangerous to wear)?
A little off-topic, but:<p>Am I the only one who finds the repeated incorrect spelling of "heterogeneous" annoying?<p>The worst part is, the way they spell it, "heterogenous", actually means something else. Just not what they think it means...
I read a lengthy article on how the edge of a straight razor reacts to being used.<p>It seems that microscopically, the honed edge of the blade looks like a comb of teeth. When you shave, these teeth fold over. Stropping apparently straightens out the folded edge.<p>Eventually these teeth break off, and the edge has to be remade. That can be done with a few strokes on a coticule, every 6 months or so.<p>The authors apparently experimented on stainless steel blades; stright razors are made from carbon steel, which doubtless has a different microcrystalline structure.<p>[I know, the article's about disposable razors]
I've noticed that a lot of the alloys for knife blades that have good edge retention are from PM (often, but not exclusively, sintered). I always assumed it was because of the types of alloys they could make, but this article suggests that the uniformity attainable through PM might be a bigger effect.
Now does stropping straighten or correct the imperfections caused as we believe or is it a useless practice? We’ve been doing it for hundreds of years with this mental model that these experiments confirm and that stropping doesn’t sharpen but merely straightens the edge.<p>Yet one must still sharpen the edge eventually.
So what if you made a razor blade of something like the monocrystaline nickel alloy used to make jet turbine blades? Would they never dull from cutting soft material such as hair?
Some discussion from when this was news 2 years ago:<p><a href="https://news.ycombinator.com/item?id=24075855" rel="nofollow">https://news.ycombinator.com/item?id=24075855</a>
> “The team’s findings may also offer clues on how to preserve a blade’s sharpness.”<p>This team is playing with fire and should tread carefully. If they should happen to stumble across the secret to a “perma-sharp” razor blade that never needs replacing, I have no doubt that “big razor” will dispatch them with a vengeance.<p>The team lead will be strolling through the park on a lazy Sunday afternoon, when a stunningly beautiful female jogger “accidentally” steps on his foot. He’ll think nothing of it, but what he won’t realize is that he was just on the receiving end of a Polonium 238 injection delivered at the order of the Gillette family.
With all of human tech and science, why do we not have better hair management by now?<p>Growth, removal, color…<p>You’d think the richest people would want to invest in that research as they grow older.
TL;DR:<p>"They found that the simulations predicted failure under three conditions: when the blade approached the hair at an angle, when the blade’s steel was heterogenous in composition, and when the edge of a hair strand met the blade at a weak point in its heterogenous structure."<p>"Tasan says these conditions illustrate a mechanism known as stress intensification, in which the effect of a stress applied to a material is intensified if the material’s structure has microcracks. Once an initial microcrack forms, the material’s heterogeneous structure enabled these cracks to easily grow to chips."