Ask A Scientist Chemistry Archive

 
name         Chrissy Ann F.
status       other
age          30s

Question -   Can you wash clothes in ocean salt? Can you bathe in ocean salt? 
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Hi Chrissy!
You can, but it does not take out the dirt. The salty water contains many salts dissolved, 
this prevents any soaps or detergent to clean by dissolving the dirt particles.

Thanks for asking NEWTON!

Mabel
(Dr. Mabel Rodrigues)                                                                                     
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 In principle yes, but the salt is not very kind to your skin and will
leave your clothes saturated with salts, so it isn't very comfortable. Also
most common detergents don't work so well in salt water.

Vince Calder
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I bet soap works better for most smudges, and I hope I get to rinse my skin with un-salty 
water before I dry off.
I'm sure there are some advantages, and some disadvantages.
Sun-dried ocean salt added to fresh water would be noticeably different than just bathing 
in surf,
because it would have less sand and organic sea-foam scum,
and because you could adjust the concentration of salt in your water.
I've read advertisements claiming it's good for your skin to bath in slightly salty water 
rather than pure,
and this sounds a bit plausible.  You'd have to see for yourself whether you actually see 
any benefit.

You could easily set up your own science experiments comparing cleaning by
plain water, soap and water, and salt and water,
for at least three different kinds of dirt.

Soap is classically considered the best thing for greasy dirt.
  Be sure you include something like a drop of melted butter on a cloth, or bacon grease, 
  or vegetable oil.
Another frequently encountered category is non-chemical particulates,
  i.e., dirty fingerprints, dried mud, or wet starch with dark-colored dust in it.
Chemically locked-together dirt results from proteins such as dried egg-yolk.
Not sure what grass-stains and red wine are due to.
  Maybe they are just large, dye-like molecules that hug their solid hosts tighter than 
  most dirt,
  or maybe there is a chemical-locking action there, too.

The expected chemical effect on cleaning is like this:
Pure water is a fairly broad-range, very polar solvent.
  Like dissolves like, so It fails to lift non-polar, greasy dirt.
Soapy water is polar water with a bit of non-polar medium dispersed throughout it.
  So it cleans most everything water cleans, plus many greasy things.
  Also a bit better at segregating dust away from the surfaces that are bathed in it.
Salt makes water more polar, but relatively few stains need an improvement in water's 
strong suit.
  Some dyes, maybe.
  For most greasy dirt, salty water is probably about the same as plain water.

Every now and then my hands get dirty with blackish, possibly oily, dust from the 
workshop.
 My first rinse with plain water carries off visible amounts of it, before I add soap.
 I get the impression that using soap first would actually slow down this removal.
 It seems to have lifted because it was water-repellant! (and cloth/hands weren't)
I think that draperies accumulate similar dust, and are therefore washed first in plain 
water with no soap.
It might be interesting to measure whether salt magnifies this effect.
Not sure yet, how best to intentionally make some of this dust.

Jim Swenson
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