≡ Menu

Can cosmetics change the acid balance of your skin? Episode 22

Do you know how cosmetics can change the acid balance of your skin? Then you should listen to this episode! Plus this week we begin a brand new feature: a game called Beauty Science or  Bull Sh*t.

Show notes

Beauty Science or Bull Sh*t

In this new game, I give Perry 3 beauty science news stories and he has to tell the real from the fake. You can play along at home – just hit the pause button before I give the answer and see if you can outsmart Perry. Here are this week’s headlines, can you tell which one is TRUE?

1. Researchers have developed a vegetable alternative to petroleum based aerosol propellants.
2. Researchers have created the first detailed 3D model of curly hair.
3. Researchers have increased skin lotion stability with oil droplets shaped like hamburger buns.

Question of the week: Does the skin’s acid mantle affect how AHA products work?

BrainyBimbo asks…I’ve been told hydroxy acid products have to be in a certain pH range to work. But I’ve used products that were NOT in that range and they seemed to work for me. Is it possible that my personal skin acid mantle changed the pH of the products so they would work?

To answer that we’ll explain three things:
1. How AHA and BHA products work
2. What the acid mantle of skin is
3. How the acid mantle changes with pH

How Hydroxy Acids work

AHAs and BHAs are chemicals with a carboxylic acid group (COOH) and a hydroxyl group (OH)

Hydroxy acids loosen dead cells to smooth and plasticize skin.

The pH of hydroxy acid and other products

  • Hydroxy acid cleaners and lotions: 3-4
  • Liquid cleansers: 5-7
  • Syndet bars: 5-7
  • True Soaps: 9-10

So what’s the deal with this acid mantle?

Just think of it as a thin protective film that covers your skin. Your body generates it from three different sources:

  • From sweat: lactic acid secreted by sweat glands along with various amino acids
  • From sebum: which is the oil produced by the sebaceous glands. This oil water proofs the skin and it’s also broken down by enzymes on the skin’s surface to form free fatty acids.
  • From dead skin: additional amino acids and pyrollidone carboxylic acid which is part of the skin’s natural moisturizing factor.

So when this oily, acidic soup gets all mixed up and is spread across the surface of your skin, it has a pH between 4.5 and 5.5 and that’s why it’s called the acid mantle.

3 functions of the acid mantle

1. Physically shield skin from the elements (wind, cold, water)
because it water proofs the skin helps keep the skin cells tight and flat so it’s harder for bacteria to penetrate your skin.

2. Provide direct protection against alkaline substances
Since the mantle is acidic it will neutralize any contaminants and other chemicals that are alkaline (that have a high pH)

3. Provide indirect protection from microbes (bacteria, fungi, and viruses)
The microbes not only have to penetrate the mantle itself but the low pH of the mantle keeps skin cells tight and flat so it’s even harder for microbes to penetrate the skin.

Now, 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.

Factors which disrupt the acid mantle

  • Environmental conditions like sunlight, water exposure
  • Diet – if you’re undernourished your body won’t produce all the right essential fatty acids.
  • Skin diseases – for example iacute eczema can raise the pH of your skin as high as 7.5 which is beyond  that protective range. To some extent the same is true for conditions like contact dermatitis which you can get from exposure to cleansing agents.
  • Systemic diseases like diabetes and some vascular diseases also increase skin pH
  • Topical product use can damage the mantle.

The mantle will restore itself but it takes time

Once damaged, it can take up to 14 hours to restore, by which time, it’s most likely under assault again from another washing. Most people wash their hands about three times a day, on average. Single washings shift pH to the alkaline region, which can shift back to normal within a few hours.

The acid mantle can NOT lower below its own pH

Hydroxy acids need to be at pH 3-4.
Acid mantle is at pH 4.5-5.5
The acid mantle can make the pH lower than its own.
Therefore, the acid mantle can’t make higher hydroxy acids work.

Will the acid mantle lower the pH of non-acidic products?

If AHA products need to be at 3 to 4 to work and they start at 6 or 7, your acid mantle will not buffer the products that low.

The bottom line: Take care of your acid mantle

The acid mantle is a powerful skin protectant and it’s important not to overstress your skin’s acid mantle or it will lose some of its protective ability.  However, you can’t rely on it to make a poorly formulated AHA product work better.


pH of common cleaning supplies http://housekeeping.about.com/od/environment/tp/Ph-Levels-For-Common-Cleaning-Supplies.htm

Study of the effects of cosmetic formulations with or without hydroxy acids on hairless mouse epidermis by histopathologic, morphometric, and stereo logic…Lúcia Helena Terenciani Rodrigues , Patricia M. B. G. Maia Campos
2002, Vol 53pp 269



LIL buy it now button

Buy your copy of It’s OK to Have Lead in Your Lipstick to learn more about:

  • Clever lies that the beauty companies tell you.
  • The straight scoop of which beauty myths are true and which are just urban legends.
  • Which ingredients are really scary and which ones are just scaremongering by the media to incite an irrational fear of chemicals.
  • How to tell the difference between the products that are really green and the ones that are just trying to get more of your hard earned money by labeling them “natural” or “organic.

Click here for all the The Beauty Brains podcasts.

Comments on this entry are closed.

  • brainybimbo March 24, 2014, 12:24 pm

    Thank you for answering my question! To clarify some things, I think you’re probably right that products outside the ideal pH range aren’t working as well as products that are within, but they are a touch gentler on my sensitive skin. Also, I generally don’t use exfoliating cleansers, I prefer my exfoliants in a form which stays on the skin, such as a moisturizer or a serum.
    Also, I don’t perform tape tests or any other specific measurable post-exfoliation tests, but if my skin feels and looks smoother (ie: the end result of exfoliation) I assume it’s working. I’ve been exfoliating for more than 10 years and I can definitely tell the difference in my skin when it’s just cleansed and moisturized and when exfoliation is incorporated.
    Drawing from your conclusions, if one has sensitive skin, it might be wise to use AHA/BHA products outside the 3-4.0 range. But it seems like it might be more adviseable to use a lower concentration product, or use high percentage products less frequently.