Previous: A Song of Ice and New Species
Next: The Great North American Megadrought



View count:504,765
Last sync:2024-04-22 04:15


Citation formatting is not guaranteed to be accurate.
MLA Full: "Why Do Things Look Darker When They're Wet?" YouTube, uploaded by SciShow, 26 May 2015,
MLA Inline: (SciShow, 2015)
APA Full: SciShow. (2015, May 26). Why Do Things Look Darker When They're Wet? [Video]. YouTube.
APA Inline: (SciShow, 2015)
Chicago Full: SciShow, "Why Do Things Look Darker When They're Wet?", May 26, 2015, YouTube, 02:04,
It’s kinda embarrassing when you spill stuff on your shirt and it makes a stain. So you might as well understand the science behind it, so at least you can act all smart and explain it to people.

Hosted by: Michael Aranda
Check out SciShow's podcast SciShow Tangents at
Spill Man: Stefan Chin
Angry Mob: Megan Toenyes, Travis Morss, Matt Gaydos, Lou Winkler, Sarah Gullickson, Valerie Barr.
Support SciShow by becoming a patron on Patreon:
Dooblydoo thanks go to the following Patreon supporters -- we couldn't make SciShow without them! Shout out to Christopher Prevoe, Justin Ove, John Szymakowski, Peso255, Ruben Galvao, Fatima Iqbal, Justin Lentz, and David Campos.
Like SciShow? Want to help support us, and also get things to put on your walls, cover your torso and hold your liquids? Check out our awesome products over at DFTBA Records:

Or help support us by becoming our patron on Patreon:
Looking for SciShow elsewhere on the internet?


So you’re hanging out with friends and being all cool and casually taking a sip of water, and then somehow, you miss your mouth … and slop it all down your front.

Now, not only are you wet, but everybody knows exactly how uncoordinated you are, because there’s a dark patch on what used to be a nice red shirt.

Well, for that you can thank physics -- the physics of light.

When light hits something, the light bends at an angle. We’ve talked about this before when it comes to mirrors -- or, depending on how you like to check yourself out, maybe spoons.

In the case of mirrors, though, the light bounces back right toward you. It’s like throwing a ball at a wall.

When light bounces back in your direction, it’s called reflection, but when light gets deflected away from you -- that’s refraction.

And just to keep things interesting, the light can also split up, with some of it being reflected and some of it being refracted. Some of it can also be absorbed, too -- It just depends on the material.

So armed with this knowledge, let’s talk about your shirt, or more specifically, the light that’s traveling through air and hitting the fabric.

While the fabric is dry, some of the light is being absorbed by it, while the rest of it is reflected back at your eyes, so you see it as red.

Then you spill.

Now there’s a layer of water clinging to the fabric, and that’s what the light hits first.

Just as before, some proportion of the light is being reflected off the water, but the rest is refracted into the water. Basically, it keeps going. But then, it hits another barrier: the fabric.

And again, some of that light is reflected, while the rest is absorbed by the fabric. But the reflected light doesn’t just head straight back toward your eyes.

I mean, it starts to travel in your direction, but once it gets to the surface of the water, some of the light goes through what’s called total internal reflection, which sounds really intense.

Instead of escaping the water and continuing its journey toward your face, it bounces back into the water for another round.

And this extra trip back into your shirt means that a larger proportion of the light gets absorbed by the fabric, which makes it appear darker.

So now you know why your shirt turned a darker shade of red when you spilled. Doesn’t change the fact that you’ve still got this embarrassing stain, but hey, at least you didn’t get your pants.

Thanks for asking, and thanks to all of our supporters on Patreon, who keep these answers coming! If you’d like to submit questions to be answered, or get these Quick Questions a few days before everyone else, go to!