I have experienced this when every time I take a bath using rain water, I just can't stop wondering why is it really hard to rinse off soap from your body?


1 Answer 1


Rain water is pretty much devoid of the minerals such as calcium salts that are often found in so-called "hard" tap water taken from underground sources. Calcium ions in tap water react with the fatty acid anions in soap to create insoluble soap scums, which (while they may remain on your skin) do not have the slippery feel of soap. Without the calcium ions present, the soap remains in soluble form (sodium salts of fatty acids) and I would propose that the slippery feel of soap on your skin comes from the traces of it that remain even after considerable rinsing.

  • $\begingroup$ The morale is of course, if showering with rain water, use less soap! ;) $\endgroup$
    – Karl
    May 11, 2020 at 18:58

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.