When it comes to the basics of skincare, questions about cleansers and cleansing are some of the most common ones that I encounter. I've noticed that there tends to be a significant amount of confusion surrounding what cleansers are, their types, and what separates a good cleanser from a bad one.
The definition of a cleanser is simple: it’s a substance that cleanses something, especially a cosmetic product for cleansing the skin. With this definition in mind, soaps, micellar waters, face washes, cleansing balms, milks and creams, among other things, all fall under the broader category of a cleanser and serve the purpose of cleaning the skin of excess sebum and impurities, such as the grime and pollution we collect on our face during the day. The difference between these different types lies predominantly in the their texture.
When shopping for cleansers, the two most important factors to consider, regardless of your skin type, are pH and harshness, or the propensity of the product to dry out your skin and strip it off its natural lipids. Both factors play an essential role in maintaining skin health.
Power of hydrogen, i.e. pH
pH is a measure of the concentration of hydrogen ions in a solution. In other words, it’s a measure of the acidity or alkalinity (basicity) of a substance. It’s a scale that ranges from 1 - 14, where 7 represents neutral, the pH of distilled water. A pH less than 7 indicates that a solution is acidic, where the smaller the number, the more acidic the solution. A pH greater than 7 indicates that a solution is alkaline, and the larger the number, the more alkaline the solution. Acids are generally sour - think lemon juice, while alkalis like baking soda, are generally bitter.
The pH of healthy skin usually lies between 4.5 and 5.5. At this pH, skin is able to renew and protect itself, and maintain optimal health. Major deviations from this optimal pH level, particularly in the alkaline direction, serve to severely disrupt the metabolism of skin and create all kinds of problems ranging from dullness and acne, to premature ageing. This is also the reason you should never use soap or baking soda on your face: the pH of soap naturally lies between 9 and 10, while that of baking soda is 9. pH is also one (and yes the italicized one here implies that there are other reasons too) of the reasons you should never apply lemons on your skin. Lemon juice has a pH of less than 2, which makes it extremely irritating.
Propensity to dry
Your skin has a thin, protective outer film of oil and other ingredients that help it retain moisture and keep harmful bacteria and other substances out. Every time you wash your face, you cause changes in that protective barrier. A good cleanser will remove dirt and excess sebum from your skin without damaging your skin’s protective film. If your skin feels tight after you wash your face, you're using a cleanser that’s stripping the skin off of its protective lipids and damaging the barrier that’s so crucial to its health. Prolonged use of such products can cause a number of problems, including acne and eczema. I know this sounds counterintuitive, because aren't drying products supposed to get rid of acne?! Not really. While in the short-term they might seem to help, in the long-term they make the condition worse. Bear with me while I explain how.
Removing the skin’s protective lipids means that water can more easily evaporate from it and leave your skin dehydrated. Since water is essential for healthy skin, your skin begins to produce even more sebum to compensate for the lost water, leading to an exacerbation of oil production for people with oily skin and consequently, to worsening of acne in those that have acne-prone skin. For those who have dry skin, harsh cleansers aggravate their dryness, leave skin more permeable to harmful bacteria and other pathogens, and often lead to uncomfortable skin conditions such as eczema. No matter your skin type though, the wrong cleanser will leave your skin looking dull and set you up for premature ageing.
In summary, if you ever thought that cleansers are something that are just meant to be washed off and don’t have a significant impact on the health of skin, I hope this post has convinced you otherwise. Always keep in mind that a solid skincare routine is always built on the foundation of a good cleanser, moisturiser and SPF. If you have these wrong, you’re only wasting your money on other expensive products, like toners and serums, to your routine.