So, in an earlier Randomness post ( click here if you are curious ) I mentioned I had purchased the Su:m37 Miracle Rose Cleansing Stick, despite the expense and difficulty in purchasing it, because I was becoming more and more engrossed in what role pH can have in your skincare.





This topic is too huge to be addressed in a single blog post, so I will be doing an ongoing series that will address different aspects of it as I collect research and form my admittedly hoi polloi understanding of it.





I will warn you before I start that this rabbit hole has no end, and therefore I will be glossing over certain terms and topics as well as reducing some explanations down to such a simplistic, generalized form as to trigger fits in any chemist wandering by my blog. (If that happens, O Chemist, please drop me a line because I have a million questions for you!)





There's a lot of misinformation out there from popular sources like the beauty 'experts' on Oprah's website , who makes claims such as: " Cleansers and toners are alkaline—hand soap typically has a pH of around 9 or 10, for example—because alkaline molecules bind to dirt and accumulated oils you want to wash off." and "Bottom Line: A claim that a product is pH balanced is more marketing tool than useful information." I admit I used to think this way, until reading Cleansers and toners are alkaline—hand soap typically has a pH of around 9 or 10, for example—because alkaline molecules bind to dirt and accumulated oils you want to wash off." and "Bottom Line: A claim that a product is pH balanced is more marketing tool than useful information." I admit I used to think this way, until reading a post from Skinandtonics on the acid mantle, which blew my mind.





So, I started to research and test it for myself, and hence me sharing the fruits of my labour with you today.





Included in this post:

What is pH, I need a refresher?

The pH of your skin, and does it matter?

The pH of your cleanser, and does it matter?

The claim that alkaline pH = efficacy, is it true?

Before we get into the pH details of cleansers, let's do a quick overview of pH in case your pre-high school science recollection is as spotty as mine.





What is pH, I need a refresher?





source in img title pH is a chemistry measurement of the acidity vs alkalinity (or 'basicity', technically alkalinity is a combination of bases that- actually, you know what, just google it. Basicity may be the correct term but it's making my inner spellcheck sense freak out and we're going to be talking about cleansers and their alkalinity so I prefer to use that term) of an aqueous solution, aka a solution of water + something.





Technically, oils can also have a pH (and in fact the pH testing of oils is necessary in such petroleum products as biodiesel) but that's a whole other topic that I'm certainly not qualified to get into.





Back to pH: pH 7 is the 'neutral' point, and anything below it is considered an 'acid', down to hydrochloric acid which has a pH of 0, and anything above pH 7 is considered a 'base' (or alkaline) all the way up to concentrated sodium hydroxide which has a pH of 14. There are substances that are considered beyond the 0-14 measurement scale known as 'superacids' and 'superbases' but since those aren't relevant to skincare, I'm movin' on here.





You can adjust the pH of something by adding a substance that is either more acidic or more alkaline, and they will react to one another. The final product will land somewhere between the original starting points, but pH is ' logarithmic' , which means that each step is 10 times higher or lower than the previous one. They may also produce other chemicals by doing so, so never try to DIY pH adjust at home, kids.





This means that anything you put on your skin that is higher or lower than it's natural pH will correspondingly raise or lower the skin's pH as well. This can either be bad (weakening your skin's defenses) or good (restoring its natural state). One of the most common 'good' uses is the use of AHA and BHA acids in skincare. They're popular for a reason! AHAs and BHAs are another day, though.





Before we go on, let me interject a plea: never use lemon juice on your skin. Ever. I know that pinterest and Michelle Phan and a whole bunch of DIY beauty gurus out there espouse the use of lemon juice as an at-home beauty treatment all the time, but please don't do it. Don't believe me? Google "lemon juice chemical burn" and have a picture of a bunny nearby for a visual chaser, because you're going to be mentally scarred afterward.





Even more important! Never use baking soda on your skin. EVER. We will go deep into why anything alkaline, or basic, on your skin is a terrible terrible idea.





The pH of your skin, and does it matter?

Yes, it matters. Specifically, it matters a great deal when it comes to maintaining the health of your skin overall, but also specifically acne. Brace yerselves for some science! Note: I have replaced the original citations of secondary sources with links to the actual source to avoid you having to dig through the primary study's bibliography. You're welcome.





One of the articles I'm going to quote at length is The pH of the Skin Surface and Its Impact on the Barrier Function , which has some excellent information not only on what can change the pH of your skin but also what negative effects it has. All of the references in this section, and the following section, are from this source unless explicitly stated otherwise. explicitly





It liberally uses the term 'syndet' which is a 'synthetic detergent', a modern era invention that does not rely on the functions of traditional soap to uh .. clean things. Phew. I was about to get lost on the surfactant/hydrophobic and hydrophilic molecule train but I stopped myself just in time!

It was a very near thing. Chemistry is fascinating! Source in image.

Healthy, acidic skin in a 'good' pH range does all sorts of wonderful things for you, like resisting bacteria, preventing your skin from losing water (called TEWL or transepidermal water loss), resisting disease, and a whole host of other sparkly things that you can read up on, if you're curious. Because this blog post is about cleansing, I'm going to focus on what cleansers do to skin's pH and fall out as a result.







The pH of your cleanser, and does it matter?

You might think that water, being pH neutral but more importantly the most common thing used in cleansing your skin, is beneficial to your skin or at least, harmless as far as pH goes. However, that's not the case:

Even rinsing the skin with water alone immediately produces a transient increase in the skin pH [ Washing the hands with conventional soap causes the pH on the palms to increase by an average of 3 units. Even 90 min after washing with soap the pH of the hands was not completely normalized .[ source ]..[ source





Ok, so not only does water raise the pH of your skin, if you raise the pH of your skin dramatically enough, such as via soap, it will continue to remain raised afterwards. In fact, later I am going to cite a study that shows that there is a cumulative long-term negative effect to spiking the pH of the skin during washing even as infrequently as twice a day.





So, what's so bad about raising the pH of your skin?

Bacteria can grow over a wide pH range, but no microorganisms will grow equally at all pH values [Note: this is important when combined with the information about the 'ideal' range for P. acnes to grow.] Most grow better at a pH around neutrality. Acidic pH could be bacteriostatic [lit: stopping bacteria reproduction without actually killing them] for some strains.





In short, bacteria grows better at a neutral pH, but an acidic pH is less bacteria-friendly. We already know healthy skin is acidic. This becomes very important when it comes to acne, as we're about to see.





The article goes on to cite a study by Korting et al. [ source, in full text!] which specifically tested the impact of using soap vs an syndet on inflammatory acne lesions in a 3-month, randomized, open- labeled , comparative trial. Within 4 weeks, the number of lesions on the soap-using group increased, whereas they decreased in acidic syndet using group. Korting et al. flat-out states: " The number of papulopustules characteristic of inflammatory acne thus is clearly lower when a syndet bar of the acidic type is regularly used for cleansing the face as compared to a (necessarily alkaline) soap. " acidiclabeledcomparative





If you're eyes are bleeding, here's the tl;dr: the high pH soap made their acne worse, and the acidic cleanser made it better.





Just take a minute to soak that in. Eye the cleansers in your bathroom. Have you pH tested them? If not, do you know what their pH is? Are you putting acne bait on your face errday?

Now just imagine all those people out there doing DIY baking soda masks and scrubs on their faces. D: