MIT Researchers Uncover How Hair Strands Can Dull Even The Sharpest Of Blades


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MIT researchers were curious how soft human hair dull sharp razor blades so effectively (Credit:

Human hair is about 50 times softer than a razor blade, which is made using heat-hardened stainless steel and often reinforced with diamond-like carbon. Yet, a few wisps of hair are powerful enough to dull a blade's sharpness within a few weeks of use. To understand how this impressive feat occurs, a team of researchers from the Massachusetts Institute of Technology (MIT) decided to take a closer look at what happens when the sharp edge of a blade slices through human hair.

"We are metallurgists and want to learn what governs the deformation of metals so that we can make better metals," Cem Tasan, a professor of material science at MIT, says. "In this case, it was intriguing that, if you cut something very soft, like human hair, with something very hard, like steel, the hard material would fail."

The team, which included graduate student Gianluca Roscioli, devised a string of experiments to keep track of the rate at which a razor blade deteriorated after each consecutive shave. The scientists found that when the blade was placed perpendicular to the hair, it sustained no damage. However, if the hair was cut at an angle, even a single strand could chip the edge of the razor blade. Once the initial crack formed, the blade became increasingly vulnerable to further chipping, accelerating its dulling. Another contributing factor was the uniformity of the microstructure of the steel from which the blade was made. Even slight imperfections could cause the blade to crack when it came in contact with the hair.

The team conducted a series of shaving experiments to observe the razor blade's condition after each use (Credit: Gianluca Roscioli/MIT. EDU)

"Our initial thought was that this was a wear problem, that material was being removed from the razor," Tasan says. "We were expecting to see that over time the blade gets rounder and rounder. We didn't see it." Instead, he continues, "We saw fracturing and chipping of the blade that is forming this C-shaped crack."

The MIT scientists, who published the findings in the journal Science on August 6, 2020, hope to conduct further research to help them to develop longer-lasting blades. They have even filed for a patent for a new manufacturing process to make razor blades harder by compressing the metal instead of heating and sharpening it, as is currently the norm. Though more expensive than conventional blades, the durable models would prove economical in the long run and also be better for the environment since fewer would be tossed in the trash. "I really believe we can build a better blade," Roscioli says.

While the study was conducted on razor blades, the researchers believe the findings could be helpful in not only creating better knives, but also retaining the sharpness of the ones you currently have. Their advice? When slicing vegetables, cut straight down instead of at an angle!

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  • soup_can11
    soup_can11Wednesday, October 7, 2020 at 12:29 pm
    Wow, who knew that hair was strong enough to cut blades? That gif with the blade cutting the hair looks a little gross.
    • tgif
      tgifMonday, November 2, 2020 at 2:53 am
      I know right? It looks like someone pulling a worm out of the ground.
    • meeeeeeeeee3
      meeeeeeeeee3Wednesday, October 7, 2020 at 9:56 am
      ONLINE SCHOOL is SOOOOOOO annoying. I read and watch Dogo news when I am in school
      • not-da-irs
        not-da-irsSaturday, October 17, 2020 at 8:17 pm
        I'm literally begging for school..
        • kittypowerrosie
          kittypowerrosieTuesday, October 20, 2020 at 3:18 am
          I go to school in-person
        • imalaser3456
          imalaser3456Tuesday, October 13, 2020 at 1:21 pm
          People say I'm lucky but I have to manage all my own work!!!
          • imalaser3456
            imalaser3456Tuesday, October 13, 2020 at 1:20 pm
            I'd rather do online school and one home schooled!!!
            • strongunicorn
              strongunicornMonday, October 12, 2020 at 12:19 pm
              I agree. But at least we get to stay home.
              • imsome1
                imsome1Friday, October 9, 2020 at 7:58 am
                Me too!
                • ii_malachichi
                  ii_malachichiFriday, October 9, 2020 at 6:41 am
                  It's not so bad, I do both real world school and online school!
                  • soup_can11
                    soup_can11Wednesday, October 7, 2020 at 12:28 pm
                    I agree with you 100%. I would much rather be in real school. :'(
                    • jad123
                      jad123Friday, October 9, 2020 at 6:05 am
                      me too :( it also feels more boring.
                  • barrrr
                    barrrrTuesday, October 6, 2020 at 9:02 am
                    • foxymoxy
                      foxymoxyTuesday, October 6, 2020 at 7:48 am
                      WOW! i did not know that hair was that strong.
                      • blaster1st
                        blaster1stTuesday, October 6, 2020 at 9:20 am
                        I don't think that the hair was strong. I think the blade was weak.
                      • bunnie_kitty
                        bunnie_kittyTuesday, October 6, 2020 at 6:21 am
                        Me: OOOOOOOH Time: Go to school! Me: -checks time- -eyes nearly pop out- Me: School time but IM watiching just a bit more cause this is impressive.
                        • bunnie_kitty
                          bunnie_kittyTuesday, October 6, 2020 at 6:17 am
                          LOL I already commented but its super coool
                          • isarabia369
                            isarabia369Monday, October 5, 2020 at 12:30 pm
                            It's still hard to believe that hair can dull razer blades.
                            • harlodina
                              harlodinaMonday, October 5, 2020 at 8:07 am
                              wow thats cool lol
                              • little_demon727
                                little_demon727Monday, October 5, 2020 at 7:27 am
                                Well it said it can dull but how much??
                                • hfm12
                                  hfm12Sunday, October 4, 2020 at 4:48 pm
                                  That's super cool