Watch the Effects of Laser Hair Removal in Slow Motion

Summer is almost here. Time to get rid of that unsightly hair. David W. Cerny/Reuters

Most everyone who stresses over bathing suit season thinks about the nuisance of having a little too much hair down there. That’s why people are increasingly turning to laser hair removal, the most popular nonsurgical cosmetic treatment. Its promise—to permanently remove unsightly hair—is a blessing for the hirsute among us.

Zapping away the hair follicle happens so fast most people don’t even think about what actually occurs on the surface of the skin. But science geek Derek Muller, host of Veritasium, a YouTube educational science channel, thought you might be interested in taking an extra close look.

The first round of laser treatment used in the video has a wavelength of 1,064 nanometers, which means it’s infrared radiation that’s invisible to the naked eye. (They also tried the procedure at even higher settings.) His camera guy made a few small adjustments so Muller could deliver the compelling footage of just what happens when the technician zaps his bicep.  

“It looks like a shootout of the O.K. Corral,” says Muller. “All of the hairs are just getting slaughtered.”

Enough with the vanity, let’s talk science: All dark eyes, skin and hair have higher levels of the molecule melanin, which provides the pigment. “Melanin absorbs a wide range of wavelengths of light, especially in the ultraviolet part of the spectrum,” says Muller. “This makes it an ideal shield for the sun’s harmful rays, which is why you get a tan when you go out in the sun.”

Short pulses are used so the melanin absorbs the light from the laser without affecting the surrounding skin. That’s why laser hair removal is most effective on people with dark hair and pale skin.

When the laser is applied to the skin, the hair heats to more than 200 degrees Fahrenheit. This, of course, burns the hair, but it also vaporizes the water. “This puffs the hair up a little bit like a Cheeto,” say Muller. The unpleasant smell and smoke—yes, smoke!—is called a “laser plume.”

According to Muller, cells are damaged when they are exposed to heat of at least 140 degrees Fahrenheit, at which point all of the various elements of cells break apart, a process known as denaturation.

An extra-close photo reveals the bubbles forming on the hair. Sure, the laser kills the hair sprouting from the skin, but it also uses this dead hair to destroy the cells that make up the follicle that produces the hair in the first place. “It’s kind of like using the hair to kill the hair,” says Muller.

“The hotter it is, the longer that temperature is maintained, the more denaturation occurs and the higher the likelihood that cell will die,” he says.

Which means, of course, that if you zap the hair with this laser enough times, the hair will never grow back. That’s why people go back for follow-up treatments.