Laser hair removal is one of today’s most common cosmetic procedures.
The treatment, which costs anywhere from $300 to $900 per session, depending on what part of you is getting treated, involves repeatedly blasting the skin with intense, ultra-fast laser pulses.
Unlike waxing or shaving, the goal of laser hair removal isn’t just to temporarily get rid of the hair. It’s to stop the growth of hair once and for all by destroying the germ cells in the hair follicle that produce it in the first place.
Derek Muller, who runs the YouTube science channel Veritasium, took a closer look at the process, sacrificing a few of his own hairs for the sake of science.
Watch a few of Muller’s hairs get zapped by lasers in the zoomed-in video below. You can see his hair “puff up like a Cheeto” before crumbling apart:
How it works
Laser hair removal makes use of a pigment in our bodies called melanin. Melanin is what gives our skin, eyes, and hair their colour. It also helps protect us from dangerous radiation from the sun. On a clear sunny day, for example, melanin in your skin will soak up the sun’s harmful UV rays before they penetrate deeper into your body.
Melanin in hair does the same thing: It absorbs radiation — be it from the sun or, in this case, a tiny laser.
And unlike ordinary light, which is made up of different wavelengths, or colours, of light, a laser beam only contains one wavelength. These wavelengths travel in unison in the same direction, creating a very narrow beam of light that can be focused on a tiny spot. The result is a very concentrated, very powerful form of energy.
As the melanin in your hair sucks up the energy from the laser, it heats up to over 212 degrees Fahrenheit. As its water is vaporized, it burns and creates a teensy burst of smoke called a laser plume.
Although it seems counterintuitive to bombard your body with intense, concentrated beams of radiation, laser hair removal is safe — as long as it’s done correctly. Just don’t expect to get a full body laser bath in one sitting. Your body can only handle small doses of radiation at a time.
The treatment works best on those with light skin (which has low amounts of melanin) and dark hair (which has higher amounts of melanin); the melanin in the hair draws the radiation away from the skin.
Getting to the root of the problem
The goal of laser hair removal is, ultimately, to stop hair growth. To do that, the procedure has to do a little damage.
Once a cell hits temperatures approaching a sizzling 140 degrees Fahrenheit, it starts to fall apart. The hotter the temperature and the longer it’s maintained, the higher the chance the cell will die. Laser hair removal capitalises on this. By damaging the germ cells in the follicle, it keeps the hair from growing altogether.
To keep the heat from spreading too far into the surrounding skin, the laser zaps the hair in a series of ultra short pulses. As the hair heats up, it damages the cells around it, but the laser turns off before the heat can spread too far or burn the skin. In Muller’s video, the procedure was done six pulses at a time, each pulse lasting 1.5 milliseconds.
This is also why people who undergo laser hair removal have to go more than once: To permanently damage the follicles producing the hair, you have to have it done roughly every six to ten weeks.
And, as always, beauty has its price. The process of shooting laser beams at your hair produces a brief flash of pain, sort of like what you might feel if someone snapped a rubber band against your skin.
Take a closer look at the process of laser hair removal in the Veritasium video below:
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