Oil Cleanser pH does not exist!
As education about skin health is growing, we are becoming more aware of things like skin barrier health, skin microbiome, and skin pH as variables that we have a certain degree of control over and as components integral to optimizing skin health.
A question I get asked often is what is the pH of an oil cleanser – specifically, our Revele Pore Purifying Oil-to-Milk Cleanser?
This question occurs because many surfactant (foamy) cleansers have a pH that is neutral or even basic (>7). But the skin has a pH that is acidic (usually 5-6). So people have heard that using products with a high pH messes up the skin’s pH, and cleansers are notoriously culprits with higher pH.
The short answer to the oil cleanser pH question is that there are certain substances that DO NOT HAVE a pH – and oils are one of them! So Revele does not HAVE a pH. We’ll get into why this is in one second. That being said, when people are asking about pH, they are asking about how acidic or basic something is. And the short answer here is that oils are usually mildly acidic.
So why can’t we measure the pH of oils?
pH is a measure of the hydrogen ion concentration of an aqueous (water-based) solution. Solutions with a high concentration of hydrogen ions have a low pH and solutions with a low concentrations of H+ ions have a high pH. I know – it’s backwards – that’s because of a minus sign in the mathematical equation that is used to calculate pH.
Since oil is insoluble in water, it’s acidity cannot be measured in terms of pH. pH is used for any and all products that contain water or ingredients that readily dissolve in water.
Measuring Oil Acidity
We can still measure the acidity of oils, however. Usually this is expressed in “percent free acidity” or “acid value.” Percent free acidity is exactly what it sounds like – the % of free fatty acids in an oil. Oils are composed of:
~ triacylglycerols (also called triglycerides. These are the main components of plant oils. Chemically, they are natural esters of a glycerol molecule with 3 fatty acids attached. The fatty acids attached depend on the unique fatty acid composition of the plant in question.)
~ small quantities of free fatty acids (we are measuring this percentage)
~ glycerol (the “backbone” of triglycerides)
~ phosphatides (another type of fatty acid ester)
~ pigments (two very common natural pigments in oils are chlorophylls (green) and carotenoids (orange – these are also powerful antioxidants))
~ flavor compounds
~ sterols (another component of oils and butters, usually waxy and thick if isolated)
~ microscopic (sometimes not so microscopic!) bits of plant and seed matter
Free fatty acids are usually created under poor storage or manufacturing conditions (high temp, high humidity, tissue damage in the plant used for the oil), which is why higher quality oils have less of them. A very high quality oil will have less than 0.1% free fatty acids. So high quality oils are actually less acidic than lower quality oils – and that’s a good thing.
Another way to measure the acidity of an oil is using the acid value (AV). It is defined as the weight of Potassium hydroxide (a strong base) in mg needed to neutralize the organic acids present in 1g of fat. Just so you can see the range, used frying oil (gross!) has an AV of 31, while virgin plant oils can have an AV of anywhere between <1 and 6ish.
The Oxidation Acidity Correlation
Antioxidants neutralize free fatty acids – so if an oil is very acidic, it is also likely oxidized. Since the free fatty acids are building up, this indicates a dearth of antioxidant activity.
How do you know how acidic an oil is? It can be measured specifically in a lab using titration (slowly adding a base to the oil until it is neutralized). But there are other signs that can help tip you off – general signs of freshness, like color, scent and taste. Basically if the oil looks, smells and tastes like it is high quality, it is! And high quality oils are generally low in free fatty acids.
How does high pH affect the skin?
On a somewhat related note – does a higher pH “mess up” the skin, and if so, how exactly? Do you need to be concerned with pH?
Short answer – yes. A study published in the Journal of Investigative Dermatology showed that increased skin surface pH caused abnormalities in both barrier homeostasis and stratum corneum integrity/cohesion.
One observed effect of increased skin surface pH was the degradation of corneodesmosomes. Corneodesmosomes are the main intercellular adhesive structures in the stratum corneum. In layman’s terms, corneodesmosomes are the glue that holds our outermost skin cells together. When this glue is affected adversely, our skin literally starts to lose skin cells, a process know as desquamation.
A certain amount of desquamation is healthy and desired. Our skin naturally sheds cells because cells are constantly getting replenished by the body. Too little desquamation can cause pore blockages, acne, and flaky, rough or dull skin. Too much desquamation however, can cause the skin barrier to become weak and thin.
So applying high pH (basic) products adversely affects our skin barrier. This in turn causes our skin to become easily irritated and red, because it has lost the ability to protect itself fully. The skin also loses moisture more rapidly, resulting in dehydration and reduced metabolic functioning of critical cellular processes.
It is true that cleansers often have a high pH and this does indeed result in the skin getting “stripped.” So if you are using an aqueous based cleanser, pH is important and good for you for checking this! If you are using an oil cleanser, you don’t have to worry about ph, but for you the main concern is oil quality.
Using a well formulated oil cleanser like Revele will not only keep your skin’s healthy bacteria undisturbed, but it will actually promote healthy pH and a healthy skin barrier.
Any questions, leave them in the comments below vs. emailing, so everyone can get the benefit of the additional info! 🙂