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Is soap bad for skin?

Anne says…Real soap is NOT problematic for all people, either on skin or on hair. Many just don’t like the feeling on hair, but if you happen to, just use shampoo every few washes to prevent buildup. And as for skin, many people have zero problem with a high pH wash off product. For those who do, there are other options yes. Sad to see this answer jump onto the bandwagon of disregarding soap without a full answer, and it just isn’t the whole truth to say that “Regular soap is not good for skin”.

The Beauty Brains respond: 

Anne’s comment comes to us from our recent post on using bar soap on hair. I agree that my original answer wasn’t detailed enough so I’ll try to correct that here.

I certainly don’t blame Anne for defending bar soap since she’s affiliated with Dot & Lil, a company which sells vegetable oil based soaps. But it’s well documented that soap is more drying to skin than surfactants. In fact, plain old ivory soap is used to dry out skin in moisturization testing!

Soaps and synthetic surfactants can dry skin

Of course that’s not to say that surfactants are perfect and that they do no harm. Anything which solubilizes oils has the potential for stripping the skin. Some surfactants, like sodium lauryl sulfate, don’t rinse well because they can interact with skin protein. The residue they leave behind is irritating so some people.

BUT, surfactants (which typically have a pH in the range of 5-7) do not upset the skin’s acid mantle as much soap which has a pH in the range of 9-10. If the mantle is washed away or neutralized by alkaline agents then the skin is more easily damaged or infected. That’s because, without the mantle, the skin cells start to separate and allow more moisture loss which in turn causes tiny cracks in the skin where bacteria can enter.  Once the mantle is depleted and the pH of skin gets above 6.5 you’re much more prone to damage and infection.

There are number of studies such (see below) that have evaluated the harshness of cleansers and have consistently found that soap is worse than surfactants.

The Beauty Brains bottom line

All cleansers have the potential to strip oils from your skin but soap has been shown to be more drying, harsher, and more disruptive to the skin’s protective acid mantle than many surfactants.

References

Interactions of cleansing bars with stratum corneum proteins
Journal of the Society of Cosmetic Chemistry 46, 301-320 November/December 1995)

Forearm wash test to evaluate the clinical mildness of cleansing products
Journal of the Society of Cosmetic Chemistry 39, 355-366 (November/December 1988)

Soap and detergent bar rinsability
Journal of the Society of Cosmetic Chemistry 37, 89-97 (March/April 1986)

{ 10 comments… add one }

  • Eileen May 12, 2014, 11:42 am

    Soap recipes have been found that date back more than 4,200 years, but just because they worked for the ancient Babylonians, it doesn’t mean that they are what we should be using today. Over the millennia, those ancient soap formulas evolved as people sought to create a better product that was easy to use, convenient to store, pleasing to the senses, and that would do the job of thoroughly cleansing without being harsh and drying. Eventually, we arrive at today’s bar soaps which are much less harsh than the primitive soaps of yore or even the ones of the past few decades, but they definitely aren’t the gentlest, most skin/hair friendly products around. That’s been proven time and time again in the lab and, if store shelves are any indication, most consumers are showing a strong preference for other skin cleansers over bar soap. The way I see it, abandoning bar soap in favor of other surfactants is just another step in the evolution of cleansers as we search for a better means of caring for our skin and hair.

  • Laurie Brown May 12, 2014, 11:54 am

    I like to use a true soap on my face, *but* my face and neck are very oily. It works perfectly for me, whereas if I use a syndet my face is shiny in no time and my makeup doesn’t stay put nearly as well. I suspect the soap/syndet thing is a case of YMMV.

  • Pedro May 12, 2014, 1:32 pm

    Out of curious, in Japan a facial cleanser that isn’t soap based (in fact, they usually are mixture of synthetic surfactants and soap) wouldn’t sell almost any there. Due to cultural reasons a facial cleanser there must make an extremely dense and huge foam – something impossible to achieve just with synthetic surfactants). Some companies even disclosure the density of the foam in microns. LOL On the other hand, they also usually contain a lot of anti-drying ingredients and people use them without to put almost any pressure during the massage with the foam. The foam is made on the hands and then applied very gently on the facial skin. I think it helps…

  • Jtest11 May 13, 2014, 2:44 am

    Interesting, been recently looking for the perfect price/performance bar or body wash.

    Most bars dry me out like crazy (especially Dove for some reason) and most washes leave an annoying film. Recently stumbled upon Old Spice’s body washes and they seem to be the only wash I can find that are simple cleansers:

    Water, Sodium Laureth Sulfate, Sodium Chloride, Sodium Lauryl Sulfate, Fragrance, Cocamidopropyl Betaine, Sodium Benzoate, Citric Acid, Disodium EDTA, Methylchloroisothiazolinone, Methylisothiazolinone, Potassium Sorbate, Yellow 5, Red 33

    Thinking I’m just gonna stick with them as a body wash/shampoo and use another moisturizer post-shower.

  • Anne May 13, 2014, 9:06 am

    Thank you for the response to my comment Perry! This is a much fuller picture. I always make sure to tell people to stick with syndets if that is what works for them. The thing is, most people do not distinguish between the two in bar form, and even more so with bars that have a mix of true soap AND syndets. Understandably it is a confusing distinction for most consumers! Add to that that handmade and handcrafted bars are not at all like most commercial bars, and it gets even more blurred. The fact that many handmade soaps are superfatted, etc. means they are unlikely to perform like the ones you have presented research for. Though again, there will ALWAYS be people who do better with a low PH syndet bar, and also those who do best to avoid foaming cleansers of all kinds, true soap or not. As a manufacturer of both bar soaps and other skincare items I spend a lot of time thinking and talking about this of course, and mainly I just think people need the correct info to make a decision. It just gets under my skin (ha!) to see bar soap presented as a non-option–and lest we forget, not all bar soap is created equal! Thanks for taking the time to present this well, I am happy to read it!

    Best,

    Anne

  • Natasha May 13, 2014, 11:13 am

    I just read the 1988 study, as a chemist myself, I found the procedure very well thought but the formulation of the soaps are not comparable (with and without synthetic surfactants), there is not a test with the same formulation (Tallow/coconut oil) with and without surfactant. It is well know that coconut oil soap is very dryer to the skin, so I was not surprised by the results, that is why it is not recommend to use over a 30% of it in a handcrafted soap. I would agree with Anne in this, not all the soaps are made equal and for someone that is looking for a real soap (with not surfactants added and glycerol still on it) a well formulated handcrafted soap could be a good alternative. Also I would not consider this paper coming from Procter and Gamble an “independent study”. Just my two cents.

  • Rachel July 7, 2014, 10:42 am

    Does tea work to cleanse hair?

    • Randy Schueller July 7, 2014, 7:27 pm

      No. (Other than the fact that tea is dissolved in water and water will rinse way dirt.)

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