Why Does Sweat Turn Shirts Yellow?

Why Does Sweat Turn Shirts Yellow?

♪ INTRO ♪ It’s maybe the most first world problem
of first world problems: pit stains on white clothing. Maybe you’ve been there. Wear any white shirt for long enough and suddenly it’s discoloring in embarrassing and irritating ways. The thing is, your sweat isn’t actually yellow. It’s colorless—that is, until it reacts with the compounds in antiperspirant. You have two main types of sweat glands, but the culprits here are the apocrine glands. These don’t kick in until puberty and are found basically anywhere there’s a lot of hair. So, your scalp, underarms… other places… They produce sweat that’s slightly thicker, and secreted onto your skin via hair follicles. To make matters worse, this sweat isn’t
just produced during hot weather. It’s also triggered by periods of anxiety or heightened emotion. Great. But to make it thicker, the sweat produced
by these glands also contains fats and proteins. And it’s those fats and proteins that are the big issue, along with the bacteria that feast on them. We’ve talked about the connection between bacteria and the odor in farts, and the smell in your armpits is produced in much the same way. Sweat itself is odorless. It’s the bacteria and the gases they release that make everything smell so wonderful, and that prompted cosmetics companies to create antiperspirants. These products generally contain some version of a compound called aluminum chloride, which works by acting as a sort of gel-like plug for your apocrine sweat glands, so you don’t produce as much sweat. But at the same time, the aluminum reacts with your sweat to produce compounds that react with the fiber in your clothing and mess with the color. Voila: yellow stains. No one seems to agree about why exactly it turns yellow, but there’s some thought that the reaction with the aluminum causes the proteins in apocrine sweat to really stick to your clothes. In any case, it’s actually the thing making
you sweat less that’s causing the stains. That doesn’t seem super helpful. Fortunately, there are a few things you can do to keep your clothes white. You could try using a deodorant that doesn’t contain aluminum, or else let it dry completely before putting on your shirt. You could also look for a type of detergent that’s boosted with the power of enzymes. Those detergents are designed to react with and break down proteins so you can get tricky stains, like yellow pit stains, out of your clothes. Like a lot of cleaning hacks, it’s all about
knowing the chemistry. Thanks to Patreon patron Garrett Van Dyk for asking this question, and thanks to all of our patrons, who keep these answers coming. If you would like to submit a question to be answered, you can go to patreon.com/scishow. And don’t forget to go to youtube.com/scishow
to subscribe! That is wonderful and helps us out, and also you’ll get a new episode of SciShow and learn more about how weird and wonderful the world is, including your arm pits. ♪ OUTTRO ♪

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About the Author: John Markowski


  1. …this video doesn't work as advertised: I had bright yellow stains on my shirt inner elbows, and ultimately changed my detergent and laundromat, which turned the stains brown, and, eventually, a later detergent reduced the stains to faint-old-shirt-color…

  2. Fat is also yellow when oxidized.
    Sweat has some fat in it, it oxidizes over time, aluminum will catalyze the reaction.
    Saved you 2 min 50 seconds.

  3. next video idea: tested and proven ways to wash clothes and clean stuff in your home. In other words, more of that chemistry!

  4. What about the opposite; white marks on black clothes? Also, I seem to sweat badly no matter what I do, even when I'm cold I sweat it sucks!

  5. I don't like plugging up all my glands, so I use deodorant instead of antiperspirant, so I also don't have any staining issues.

  6. But I have a deodorant containing only coconut oil, baking soda, tee tree oil and corn starch. The armpits on my white shirt still turns yellow. So it can't be the aluminum ๐Ÿ™

  7. Dude! Why did you say which patron asked the question?! Why did you drop his name and throw him under the bus like that! Poor guy!

  8. My antiperspirant doesn't contain aluminum, yet I still get stains. There must be more to it than just the antiperspirant…

  9. Ive been a long time die-hard fan. But in late years ive stopped watching as much. In the beginning you were covering far more sciency topics and interesting stuff in general. Now, i don't know. Its not that interesting

  10. I've actually been researching it myself by just looking what kind of deodorants give yellow stains in armpits, and I've noticed that only deodorants that contain alcohol, give such stains. ๐Ÿ˜‰ you are welcome.

  11. Just don't wear white~
    No, really, I never had any problems with this stuff. I read about it, advertisement yells at me about it, but I never had any sweat or deodorant stains on my clothes.
    Aluminium salts in Deodorants can increase the risk of developing Alzheimer's, by the way. That's a way better reason for using aluminium-free deodorant. At least in my opinion. What's a ruined shirt?

  12. That is not truth. I am working alone on the fresh air and do not use deodorants (they are unhealthy). All my white t-shirts become yellow anyway.

  13. This is a bit half-as*ed for sci show. Sweat sure AF has an odor if you're nose is functioning. It may not be horrible or super strong, but that's the same thing as non-existent. I don't get yellow stains even though I exercise sweating heavily and use an aluminum containing antiperspirant.

  14. "It's all about knowing the chemistry" Not when it comes down to cleaning the house since you still have to do a lot of work. For that matter, it's all about knowing robotics!

  15. I'm wondering if different brands have different amounts of aluminum and maybe he amount matters. I've had terrible dark yellow stains with one brand (and for women this occurs on bras too!) but I switched to another brand, still with aluiminum, and no more pit stains. Interesting.

  16. Well you shouldnt use aluminium deodorants anyway, because the aluminiumon this small level can enter the brain barrier and cause alzheimers

  17. Oh the irony. I didn't want to get yellow stains on my favorite (white) shirt, so I'd always put on extra anti-perspirant whenever I wore it. Whoops

  18. Hold on, my white t-shirts turn yellow EVERYWHERE, not just under the armpits where I'd use deodorant
    And what about my pillow? Why does that turn yellow?

  19. Itโ€™s not yr sweat but deodorants that colour it yellow . . . Oops Iโ€™m watching the vid while commenting and yep not a good idea if yr trying to look knowledgeable but they cover this in the vid,

  20. I use deodorant and I don't think it has aluminum and the arm pit stains are black I've tried changing my deodorant but it still happens can someone help

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