Why is it that clothes might turn white after sweating?

  • Welcome to Health.SE! For a number of reasons outlined in this meta post, we can not, and will not, give personal medical advice. If you have a question regarding your personal health, you should see a doctor. For further information on how this site is supposed to work, what is on-topic or not, you can take the tour, visit the How to Askpage and Medical Sciences Meta. This post explains question closure. The focus on clothes may fit better on LifehacksSE? May 29 '18 at 11:02
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    @LangLangC So if I put the focus on health the question can be opened up again? May 29 '18 at 12:56
  • If it gets closed, and you attempt an edit in that direction, most probably yes. A proper edit might even prevent the closure from happening. Take the tour and read How to Ask. Document your own prior research on this and keep it general, with a focus on health and/or medicine. May 29 '18 at 13:18
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    It's just salt from dried sweat. Perfectly normal. You must be very young if you've just noticed this.
    – Carey Gregory
    May 29 '18 at 13:54
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    Well, either you never sweated until you were 22 or you just never noticed it until recently. I'm going with never noticed.
    – Carey Gregory
    May 30 '18 at 0:39

Sweat contains a concentration of salt:

Sweat is mostly water. A microfluidic model of the eccrine sweat gland provides details on what solutes partition into sweat, their mechanisms of partitioning, and their fluidic transport to the skin surface. Dissolved in the water are trace amounts of minerals, lactic acid, and urea. Although the mineral content varies, some measured concentrations are: sodium (0.9 gram/liter), potassium (0.2 g/l), calcium (0.015 g/l), and magnesium (0.0013 g/l).

Relative to the plasma and extracellular fluid, the concentration of Na+ ions is much lower in sweat (~40 mM in sweat versus ~150 mM in plasma and extracellular fluid). Initially, within eccrine glands sweat has a high concentration of Na+ ions. In the sweat ducts, the Na+ ions are re-absorbed into tissue by epithelial sodium channels (ENaC) that are located on the apical membrane of epithelial cells that form the duct.

Many other trace elements are also excreted in sweat, again an indication of their concentration is (although measurements can vary fifteenfold) zinc (0.4 milligrams/liter), copper (0.3–0.8 mg/l), iron (1 mg/l), chromium (0.1 mg/l), nickel (0.05 mg/l), and lead (0.05 mg/l). Probably many other less-abundant trace minerals leave the body through sweating with correspondingly lower concentrations. Some exogenous organic compounds make their way into sweat as exemplified by an unidentified odiferous "maple syrup" scented compound in several of the species in the mushroom genus Lactarius. In humans, sweat is hypoosmotic relative to plasma (i.e. less concentrated). Sweat is found at moderately acidic to neutral pH levels, typically between 4.5 and 7.0.

Just as the salt from antiperspirants can stain dark clothing, excessive sweating can leave a ring of white salt on dark clothes. Often you'll notice dark colored shirts with white rings around the collar after profuse sweating. Usually this salt will wash out during a normal wash cycle, but you may wish to soak the material is cold water to dissolve the salt if the stains are tough to remove.

  • So how can I combat this? Eat less salt? May 29 '18 at 10:49
  • @Otsukisama I think it is not a health issue. So wash the clothes to remove white stain. I also had this problem, Over the period of time it's gone
    – Gunaseelan
    May 29 '18 at 10:51
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    I've edited the question to comply a bit better with site guidelines. If you think that changes your post too much, feel free to revert it. If you think you might improve it further, for example with better references, or factors influencing the severity of the phenomenon (along: "eat less salt?") please edit it again instead of adding relevant infos in comments (which are volatile and may be deleted anytime). May 29 '18 at 22:01

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