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: MIT.edu)

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!

Resources: Smithsonian.org, news,mit.edu.

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103 Comments
  • breathofthewild
    breathofthewildTuesday, October 20, 2020 at 4:23 pm
    Wow, that is very interesting and I never would have thought that hair can break steel.
    • kittypowerrosie
      kittypowerrosieTuesday, October 20, 2020 at 3:17 am
      In the video, the strings of hair looked shiny like they had tinfoil on them
      • panda_payton321
        panda_payton321Saturday, October 17, 2020 at 8:29 pm
        I’m going to MIT😁
      • not-da-irs
        not-da-irsSaturday, October 17, 2020 at 8:16 pm
        they should make armor out of hair :)
        • chocoman
          chocomanSunday, October 18, 2020 at 8:48 pm
          good idea
        • robloxmaster
          robloxmasterFriday, October 16, 2020 at 12:24 pm
          online school is BORING!!! like if you agree!
          • kotlcfitzphie13
            kotlcfitzphie13Monday, October 19, 2020 at 1:57 pm
            I actually like it. I finish my work a whole lot faster! I get a ton more free time!
            • rand
              randTuesday, October 20, 2020 at 1:59 pm
              me to its awsome
              • imsome1
                imsome1Monday, October 19, 2020 at 5:06 pm
                I kinda drift off because there is a computer right in front of me and I begin to read DOGOnews so I get distracted
            • strongunicorn
              strongunicornMonday, October 12, 2020 at 12:18 pm
              I know, and I love all of you comments but what I think might me crazy. I think my hair is stronger than that and I know that might sound weird but it is true.
              • bloodmoonfire
                bloodmoonfireMonday, October 12, 2020 at 9:13 am
                same thing
                • cohhed
                  cohhedFriday, October 9, 2020 at 12:02 pm
                  interesting I would have never thought that.
                  • 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.
                    • 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.