Skin

Don't Blame Your Sweat For Pit Stains

Ugh, sweat. Alongside excess body hair and a stubborn need to store energy as fat, sweating is one of the many annoying ways your body works to ensure your survival. (It means well, we're sure). It may surprise you to learn, however, that when it comes to the yellow pit stains on your favorite white cotton tee, sweat's not to blame. Not sweat alone, anyway.

Chemistry Strikes Again

The true culprit behind yellow underarm stains is a chemical reaction among the proteins in your sweat, the cotton in your shirt, and the aluminum salts in your antiperspirant or deodorant. Yes, the very thing you use to keep yourself looking and smelling fresh is the reason your white undershirts start looking so gnarly after a few dozen wears. You can also blame that disgusting chemistry for the stiff texture that comes with those stains.

In fact, because aluminum-based deodorants are a relatively recent phenomenon, pit stains haven't always been yellow. Around the turn of the 20th century, one of the most popular antiperspirants was a product called Odorono. Despite containing aluminum, the substance itself was red in color, and that led to red underarm stains. When it comes to clothing artifacts from history, textile conservators run into sweat stains ranging from yellow, orange, and red to brown and even green. Fun fact: astronaut sweat has even corroded the metal components in the spacesuits of history. (If even astronauts deal with armpit sweat, maybe we don't feel so bad about ourselves).

An Ounce Of Prevention

Unfortunately, to prevent pit stains, the first thing most people resort to is just using more antiperspirant. That's obviously the wrong choice, as we've explained above. You could try switching to a non-antiperspirant deodorant that doesn't contain aluminum salts, although that may just end up trading big yellow marks for big wet marks.

The best solution is probably to tackle pit stains right after you've worn the shirt. For new, un-yellowed garments, try pre-treating with an enzymatic laundry spray directly after you wear it (keep the spray by the laundry hamper to make things easier on yourself). If your antiperspirant has already done its damage, soak the shirt in vinegar, hydrogen peroxide, or an oxygenated bleach like OxiClean to try and get the yellow out. Important, though, is to never use chlorine bleach, which actually yellows in the presence of proteins like those found in your sweat.

Why Do We Sweat?

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Key Facts In This Video

  1. The average person has 2.6 million sweat glands in their skin and can produce up to 3 liters (0.79 gallons) of sweat per hour. 00:25

  2. Sweat is odorless, but the bacteria that feast on it release smelly compounds. The best way to reduce this is to keep up with regular hygiene. 00:46

  3. 1.6% of humans have a genetic trait that keeps them from stinking when they sweat. 02:22

Written By
Curiosity Staff
July 22, 2017