How to exfoliate the skin: the best exfoliation guide

Exfoliation is a crucial step in any skincare regimen, yet it is one of the most misunderstood practices...For years I got exfoliation all wrong ! My biggest mistake was to use products and tools that were unbelievably harsh like these :

In this post, we'll explore the right way to exfoliate the skin drawing on scientific principles and evidence-based practices to offer a real perspective on how to achieve radiant, healthy skin through exfoliation.

Introduction: The Science of Exfoliation

The human skin, our largest organ, is a dynamic system constantly undergoing renewal. At the heart of this process lies exfoliation, the shedding of dead skin cells from the surface. This natural desquamation process typically takes about 28 days in young, healthy skin. However, as we age or encounter various environmental factors, this cycle can slow down, leading to the accumulation of dead skin cells. This build-up can cause dullness, congestion, and an uneven skin tone.

Exfoliation, whether through physical, chemical, or enzymatic methods, aids in accelerating this natural process, revealing the fresher, younger cells beneath. But how do we ensure that we're exfoliating effectively and safely? Understanding the science behind exfoliation can help us make informed decisions that go beyond the typical advice found online.

The 3 Types of Exfoliation: Physical, Chemical, and Enzymatic

Physical Exfoliation:

Physical exfoliation involves the mechanical removal of dead skin cells through abrasive materials. Common examples include scrubs with small granules, microdermabrasion devices, and cleansing brushes. The mechanism is straightforward: friction created by the abrasive particles dislodges the outer layer of dead skin cells, revealing smoother skin underneath.

However, not all physical exfoliants are created equal. The size, shape, and hardness of the exfoliating particles play a significant role in determining their efficacy and safety. For example, walnut shell or coffee powder, once popular, has fallen out of favor due to its irregular shape, which can cause micro-tears in the skin. The same happens wit salt and sugar scrubs which do more harm then good.

Should you avoid physical exfoliation?

Not necessarily.

It's important to choose the right product though. We want to look at materials with perfectly shaped round particles that are not too abrasive. There are 3 products I recommend if you want to start exfoliating the skin through physical exfoliation:

- The first is this. These are alumina particles that you can add to any cleanser or oil. They're extremely effective while still being gentle. I use this product once every 2 week on my face.

-The second is the Luisa True Skincare powder cleanser with pumice. This offers such a gentle exfoliation that can be used daily.

-The third is this body scrub from The Necéssaire. I use this once a week in the shower. It's made with pumice crystals just like the Luisa True Skincare powder cleanser. 

Other exfoliants smoother and gentler are milled jojoba beads that offer effective exfoliation without damaging the skin.

Pros and Cons:

Physical exfoliation provides immediate results and a satisfying experience - I love touching my skin right after exfoliating!

This kind of exfoliation can be too harsh for sensitive skin types or individuals with conditions like rosacea, where the friction can worsen redness and irritation.

Chemical Exfoliation:

Chemical exfoliants work by loosening the bonds between dead skin cells, allowing them to be easily sloughed away. The most common chemical exfoliants are Alpha Hydroxy Acids (AHAs), Beta Hydroxy Acids (BHAs), and Polyhydroxy Acids (PHAs).

 

AHAs (e.g., glycolic acid, lactic acid) are water-soluble acids derived from fruits and milk. They work on the surface of the skin to dissolve the intercellular glue that holds dead cells together. Glycolic acid, with its small molecular size, penetrates more deeply, making it highly effective. Lactic acid, being gentler, is often preferred for sensitive skin.

 

BHAs (e.g., salicylic acid) are oil-soluble, making them ideal for treating acne-prone skin. There's only one BHA you need to now and it's Salicylic acid. Because of its non polar chemical structure, it penetrates the pores, dissolving sebum and preventing clogging, which helps reduce acne and blackheads. Let me save you some money: no need for BHAs unless you have oily skin or enlarged pores.

 

PHAs (e.g., gluconolactone) are newer, less common acids. They have a larger molecular structure, making them less likely to penetrate deeply, which reduces irritation. PHAs also offer additional moisturizing benefits, making them suitable for dry or sensitive skin. Don't bother with these before trying AHAs and BHAs.

Pros and Cons:

Chemical exfoliants offer a controlled and uniform exfoliation compared to physical methods. They can be tailored to different skin types and concerns, making them versatile. However, improper use, such as over-exfoliation or using a product with the wrong pH, can lead to irritation, sensitivity, and a compromised skin barrier.

Just don't overdo it.

Enzymatic Exfoliation

Enzymatic exfoliation uses natural enzymes to break down the keratin protein in dead skin cells. Common enzymes used include papain (from papaya), bromelain (from pineapple), and pumpkin enzymes. These enzymes work by digesting the proteins that hold dead skin cells together, allowing for gentle exfoliation.

Pros and Cons:

Enzymatic exfoliation is often touted as the gentlest form of exfoliation. It is particularly suitable for sensitive skin, as it does not involve the mechanical action of physical exfoliants or the potentially irritating effects of chemical acids. However, enzymatic exfoliants can be less effective on tougher, more resilient skin types. In other words, the science just isn't there. There's basically no proof these enzymes actually exfoliate the skin, and for this reason, I don't recommend them. 

Correct exfoliation for your skin type

One of the most critical aspects of exfoliation is tailoring the method to your skin type. Different skin types respond differently to exfoliation, and understanding these nuances can make the difference between glowing skin and compromised barrier.

Sensitive Skin: Sensitive skin is prone to redness, irritation, and inflammation. For this skin type, it's crucial to avoid harsh physical exfoliants and high concentrations of chemical exfoliants. Mild AHA like lactic acid can be beneficial, but frequency should be limited or adjusted to your specific sensitivity.

Oily and Acne-Prone Skin:  BHAs, particularly salicylic acid, are ideal for this skin type due to their ability to penetrate the pores and reduce sebum production. Physical exfoliants can also be used, but avoid over-scrubbing, which can stimulate excess oil production.

Dry and Dehydrated Skin: Dry skin requires careful handling to avoid further moisture loss. Lactic acid is an excellent choice as it exfoliates while providing hydration. Over-exfoliation can lead to a compromised barrier, so the frequency should be adjusted accordingly, and don't forget to use a moisturizer post-exfoliation

Combination Skin: A targeted approach works best—using BHAs on the T-zone and gentler exfoliants on the drier areas. Multimasking and spot treatments can also help balance the skin.

Hyperpigmentation and Aging Skin: Exfoliation plays a significant role in treating hyperpigmentation and signs of aging. AHAs, particularly glycolic acid, are highly effective in promoting cell turnover and fading dark spots. 

The Role of pH in Exfoliation

The pH is a critical factor in the effectiveness of exfoliants. Yet no one talks about it.

 For chemical exfoliants to work effectively, they need to be formulated at low pH. How low?

The lowest, the better even though we can't go below 3 for skincare products. This is a requirement, and here's why.

All acids are always in equilibrium between their undissociated and dissociated form, but only the undissociated form is able to penetrate the skin.  This means that the formulator's job is to make sure this undissociated form is prevalent in the product or it won't work. The way to control this factor is the pH. Every acid has a pKa value that correlates to the pH according to the The Henderson-Hasselbalch equation. This equation is

 

pH = pKa – log ([Acid]/[Salt])

In graphic terms:

In simple terms, this means that the lowest the pH the higher the amount of the undissociated form. 

Let's see an example.

Product A: 10% glycolic acid with a pH of 5

Vs.

Product B: 8% glycolic acid with a pH of 3.5

At first glance, you might think Product A (with the higher 10% concentration) is more powerful than Product B (with just 8% glycolic acid). However, the pH levels tell a different story.

Product A (10% Glycolic Acid, pH 5)
pH = 5
Glycolic acid's pKa is 3.83.

At pH 5, significantly less glycolic acid will be in its undissociated form, meaning the acid won’t be as effective at penetrating the skin.
According to  the Henderson-Hasselbalch equation:

pH = pKa - log ([Acid]/[Salt])

At a pH of 5, there will be less undissociated glycolic acid available. Only about 10-20% of the glycolic acid is in the undissociated form, so even though the concentration is higher, the product’s effectiveness will be less.

Product B (8% Glycolic Acid, pH 3.5)
pH = 3.5

At pH 3.5, the product is much closer to glycolic acid’s pKa (3.83). This means a much larger percentage of the glycolic acid—roughly 60-70%—is in its undissociated form, ready to penetrate the skin.
Despite having a lower acid concentration (8%), Product B will be much more effective than Product A because more of the glycolic acid is active and able to exfoliate (to come up with those percentages you need to solve the equation).

Exfoliation Myths

The internet is excellent at spreading misinformation on exfoliation. Let's debunk some myths together, shall we?

• Myth 1: The more exfoliation, the better. It's easy to fall into the trap of thinking that more exfoliation will lead to better skin. The truth is that over-exfoliating damages the skin...a lot! It basically leads to increased sensitivity, redness, and a compromised skin barrier.

• Myth 2: Exfoliation Thins the Skin. This is a common concern, but it's baseless. No skincare product will ever modify the anatomy or physiology of your skin, no matter how often you use it. Actually proper exfoliation, when done correctly and at the right frequency, promotes healthy cell turnover and thickens the epidermis over time. 

• Myth 3: Natural Exfoliants Are Always Better. The term "natural" is often perceived as  "better" or "safer," but this isn't always true . Some natural exfoliants, like crushed walnut shells, can be too harsh and cause micro-tears in the skin. 

 

How and how often should you exfoliate?

Good question! Finding the right frequency makes a difference between effective exfoliation and damaging one. Over-exfoliation can lead to a compromised skin barrier, while under-exfoliation can result in dullness and congestion.

Oily skin may benefit from more frequent exfoliation (e.g., 2 max 3 times a week), while sensitive skin may only tolerate exfoliation once every 2 weeks.

Mature skin  requires more frequent exfoliation to boost cell turnover, but it should be done gently to avoid irritation and never more than 2/3 times a week.

In general start with once a week and eventually increase as tolerated.
Monitor the skin for signs of over-exfoliation, such as redness, tightness, or peeling.
Always follow up with a moisturizer.

In fact, after exfoliation, the skin may be more prone to water loss, so it's important to replenish moisture levels. Look for ingredients like hyaluronic acid, glycerin, and ceramides that help to hydrate and repair the skin barrier (all in our Essential Moisturizer).

Sunscreen Protection: Exfoliated skin is more susceptible to UV damage, making sunscreen a non-negotiable part of post-exfoliation care. A broad-spectrum sunscreen with at least SPF 30 should be applied daily.

Soothing Ingredients: Ingredients like vitamin E, bisabolol, and panthenol can help soothe any irritation and calm the skin after exfoliation.

 Exfoliants: conclusion

As a cosmetic formulator, I love the complexity of creating an effective exfoliant. It's not just about choosing the right active ingredients; it's more about creating a symphony—a well-balanced formulation that considers concentration, pH, stability, and the interplay with other ingredients.

Here's the exfoliant I created for Luisa True skincare. A 10% glycolic acid stabilized at pH 3.5 and coupled with soothing ingredients like panthenol and vitamin E.