Welcome to brain Stuff production of iHeart Radio. Hey brain Stuff, Lauren bog Obam. Here. If you're a human who grows hair and occasionally attempts to remove some of it, there's a decent chance that you've stood over the bathroom sink or in the shower and wondered, how is it possible that your hair can dull a razor blade. Hair is notoriously strong for its thickness, but come on, it's a stainless steel razor blade. That's gotta be stronger than a
little old strand of hair, right. It turns out scientists have wondered the same thing, and now we've got an answer, and that answer is heterogeneity, of which is when an object's composition isn't completely uniform. But let's back up. So hair is indeed softer than steel. You might have noticed this yourself. It's about fifty times softer than the stainless steel used in razor blades, and yet the race or
blades we used for shaving get dull fairly quickly. A team of scientists at m I t S Department of Material Signs and Engineering wanted to find out why, and their results were published in August and the journal Science. Researcher Jean Luca Or Sholey started by shaving his own facial hair with disposable razors and taking those blades into the lab to be examined with a scanning electron microscope. He found that the edges of the metal weren't rounding
or being worn down as you might expect. Rather, they were chipping and cracking. So he created a mechanized shaving apparatus in the lab for a more controlled testing, and he built it to fit inside that electron microscope. He used hair from himself and his lab mats, and blades from commercially available razors. What were Sholey and his co authors on the study found was that chips were more likely to occur in the blade's edge when the hair was able to bend before being cut by the blade.
So the team went even further to create computer simulations with more variations different hair, different cutting angles, different directions of force being applied, and different materials used in the blade. They found that the chips appeared under three conditions, when the blade approached to the hair at an angle, when the blade was heterogeneous in composition, and when the hair met the blade at a week point. Heterogeneous means that
the blades material is not perfectly uniform. Thus, there are microscopic imperfections in the steel that allowed chips to happen when it comes into contact with something, even something as relatively soft as a hair. The presence of those tiny cracks in the material increases stress to the rest of the material, meaning that when there's one chip, there will be more chips breaking apart that fine edge and resulting
in a dull blade. The researchers are now working on creating a more homogeneous or uniform steel material for sharper, longer lasting blades. Today's episode was written by Kristen hall Geisler and produced by Tyler Clang. For more on this and lots of other sharp topics, visit how stuff works dot com. Brain Stuff is production of iHeart Radio or more podcasts. My heart Radio visit the iHeart Radio app, Apple Podcasts, or wherever you listen to your favorite shows.