In cosmetology, exfoliation is the process of removing dead skin cells from the outer layer of the epidermis, the stratum corneum. Methods of doing so range and can be categorized into two separate groups: physical and chemical. Physical exfoliation is the process of using abrasives to manually scrub away dead skin cells and include things like physical scrubs, washcloths, and facial brushes. Chemical exfoliation on the other hand is when acids are used to dissolve dead skin cells and can penetrate deeper inside the pores to clean them.
Why is Exfoliation Important?
Exfoliation assists in the skin’s natural cell turnover process where dead skin cells are removed. This process begins in the deepest layer of the skin, the stratum basale, where new healthy cells are produced. From there, the cells travel through the other layers of the epidermis until it reaches the uppermost layer, the stratum corneum. This is also known as the dead skin layer since it’s the final stage of cornification forming a cornified layer of skin cells.
This process is important because accumulation of dead skin cells may cause skin concerns such as dullness, aging, uneven skin tone, breakouts, and acne. Proper exfoliation can help address these concerns. However, over-exfoliation of the skin can strip the skin barrier leading to redness and irritation. Therefore, it’s important to use exfoliation at proper intervals and contact a dermatologist with any concerns.
Breakouts, Acne, and Textured Skin
The oils, debris and dead skin cells that naturally get trapped inside the skin’s pores create the ideal environment for bacterial growth. This clogging of the pores can cause acne-related concerns such as blackheads, pimples, acne cysts, and nodules. Exfoliation works to minimize the chances of acne-forming bacteria by unclogging the pores of such impurities.
Dullness, Hyperpigmentation, and Aging
On average, millions of dead skin cells are shed every day, preventing the skin from reflecting light and causing it to have a dull, ashy look. Exfoliation can brighten and even out the skin tone by removing these excess dead skin cells. If used over time, the appearance of the skin becomes smoother and hyperpigmentation may even become less visible. Similarly, exfoliation can assist with making wrinkles and fine lines less prominent due to the top layer of the skin being recharged.
Effectiveness of Skincare Products
Most skincare products have trouble penetrating deep into the skin when an extra layer of dead skin cells are present. Since they cannot penetrate as much, the effectiveness of their active or nourishing ingredients may be diminished. Many moisturizers, for example, are able to go deeper into the skin to retain their moisture for longer periods if that outer cornified layer is removed.
Physical Exfoliation
Although popular in the cosmetic industry due to its immediate results, the abrasiveness of physical exfoliation can damage the skin by causing small micro tears in the epidermal layer. This layer acts as a waterproof barrier that protects the skin from viruses, bacteria, and irritants. With micro-tears in this barrier, these harmful substances are allowed into the skin, causing skin infections and irritation. Therefore, many dermatologists recommend using chemical exfoliants to remove dead skin cells as they are safer and do not cause microtears.
Chemical Exfoliation
Chemical exfoliants tend to be more gentle on the skin compared to physical methods. The acids that can be used range from mild, over-the-counter agents to stronger, prescription formulas.
AHAs
Alpha hydroxy acids (AHAs) are groups of plant and animal-derived acids that are common in exfoliation products. Since they have less irritating effects, they are popular over-the-counter products, even used to treat other skin concerns beyond exfoliation. The hydroxyl part of the acid is separated by two carbon atoms, making it more water-soluble. Common AHAs include glycolic acid, lactic acid, and mandelic acid.
Glycolic Acid
Glycolic acid is the most common ingredient used for exfoliating cosmetic products. It can be found in various concentrations depending on the product it is in: peeling solutions tend to have high concentrations while toners have lower ones.
The acid is derived from sugarcane and has a rather small molecule size, enabling it to penetrate deep into the skin’s layers. As a result, glycolic acid can be quite powerful, causing irritation or burns to certain individuals. Those with dry and highly sensitive skin often experience redness after application.
Lactic Acid
Lactic acid is derived from milk and has larger molecules compared to the former. This makes it a less effective exfoliant alternative to glycolic acid, but can be better for those who need gentler and more moisturizing formulas. It works by mildly swapping off dead skin cells without penetrating the skin layers.
Mandelic Acid
Mandelic acid comes from the hydrolysis of bitter almonds, with even larger molecules. This makes it the most ideal for people with sensitive skin, as it’s most mild and penetrates the skin at a slower rate, lessening irritation. It also has the ability to regulate oil levels to decrease chances of breakouts.
BHA
Beta hydroxy acid (BHA) is an oil-soluble acid commonly derived from leaves or bark. Salicylic acid, which comes from willow barks specifically, is the most common type of BHA. It is able to penetrate deep into the pores of the skin to unclog them, due to its oil-soluble property. This can dissolve debris and help with inflammation, both of which contribute to pimples. This makes it ideal for those with oily or combination skin type.
PHA
Polyhydroxy acid (PHA) is a water-soluble acid produced by a variety of prokaryotic microorganisms through bacterial fermentation. The microbes produce the PHA polymer, which can be managed in an industrial setting. Although they are less common compared to AHA and BHA, they have recently experienced rising popularity.
Similar to AHA, they are able to gently exfoliate the outer layer of the skin with less irritation. But PHA molecules tend to be much larger, limiting them to only working on the surface. Commonly used ones include gluconolactone and lactobionic acid.
Gluconolatone
Gluconolactone is derived from gluconic acid. Its large molecule structure enables it to only penetrate through the first layer of the skin, reducing the chances of redness of flaking. It helps with dissolving dead skin cells and acts as a humectant that moisturizes the skin by pulling moisture from the air. Due to its mild exfoliation, it can be used for most skin types with few chances of side effects.
Lactobionic Acid
Lactoboinic acid comes from milk, which is an oxidized form of lactose. Since it does not penetrate the skin deeply, less irritation follows application. It also works as a humectant that moisturizes the skin and has antioxidant properties, which protects the skin from environmental pollutants.
References
1. Different Types of Exfoliation. esmi Skin. https://www.esmiskin.com/blogs/esmi-skin-central/different-types-of-exfoliation
2. How to safely exfoliate at home. www.aad.org. https://www.aad.org/public/everyday-care/skin-care-secrets/routine/safely-exfoliate-at-home#:~:text=Exfoliation%20is%20the%20process%20of
3. Chemical Vs. Physical Exfoliation: Which Is Better? Moon Juice. Accessed May 26, 2024. https://moonjuice.com/blogs/tips-and-tricks/chemical-vs-physical-exfoliation
4. Dr. Sam Ellis. Best Exfoliators for Your Skin Type: Dry, Oily, Combination, Normal, & Sensitive | Derm Picks. YouTube. Published March 6, 2024. Accessed May 26, 2024. https://www.youtube.com/watch?v=r0qvmJN_huA&t=475s&ab_channel=Dr.SamEllis
5. Dr. Aanchal MD. How to exfoliate | who needs it| who should avoid | Dermatologist explains. YouTube. Published December 27, 2023. Accessed May 26, 2024. https://www.youtube.com/watch?v=00a4m3XoUl0&ab_channel=Dr.AanchalMD
6. Know Your Exfoliants: Glycolic, Mandelic & Lactic Acid. Minimalist. Accessed May 26, 2024. https://beminimalist.co/blogs/skin-care/confused-about-ahas-know-your-exfoliants-read-the-benefits-of-glycolic-mandelic-lactic-acid
7. Alpha Hydroxy Acid: 8 Skincare Benefits and How to Use it. Healthline. Published February 1, 2018. https://www.healthline.com/health/beauty-skin-care/alpha-hydroxy-acid
8. Jacques R, Dancer R. What Does Salicylic Acid Do For Your Skin, Exactly? Allure. Published June 7, 2019. https://www.allure.com/story/what-does-salicylic-acid-do
9. Nast C. Why PHAs Are Going to Be One of the Biggest Skin-Care Trends. Allure. Published January 24, 2019. https://www.allure.com/story/what-are-phas-polyhydroxy-acids
10. Gluconolactone for Skincare: What You Need to Know. www.grove.co. Accessed May 26, 2024. https://www.grove.co/blog/gluconolactone-for-skincare
11. Gluconolactone. Puracy. Accessed May 26, 2024. https://puracy.com/blogs/ingredients/gluconolactone#:~:text=Gluconolactone%20is%20manufactured%20by%20removing
Author: Kevin Zheng
