Continuing my series,
Part 1: Introduction to Skincare
Part 2: Rules to Skincare
Part 3: All about Cleansing 1 & 2
Skincare Series Part 4:
Exfoliation – The Process
This post will focus on :
Understanding exfoliation – What is Desquamation?
Is it necessary to exfoliate?
Physical exfoliation v/s Chemical Exfoliation
When should you begin exfoliating?
Limitations to Exfoliating
Is Exfoliation for you?
Exfoliation & sensitive skin
How to identify over exfoliated skin?
For someone just starting out with skincare, exfoliating can seem complicated, overwhelming & scary. While there are a ton of chemical and physical exfoliants available in the markets now, picking the one that suits your wants and needs can be complicated. I will try to discuss common treatments & exfoliants in my next skincare series post but this one will pivot around exfoliation as a process.
Before we can understand what exfoliation is, it is important to understand desquamation.
1. What is Desquamation?
Desquamation is our body’s natural exfoliation mechanism by which Keratinocytes 1 (cells that originate in epidermis basale) move up, turnover, die (turn into Corneocytes), detach from other cells and shed individually. This process normally takes 28-35 days in a healthy adult.
Desquamation is a continuous natural process of the skin that happens daily. Under normal circumstances, it happens every day at a microscopic level and remains mostly unnoticeable to the eyes. Desquamation is an active process. This means our skin cells do not need any external factor to invoke the process. Using a non-exfoliating face wash or friction from drying your face with a towel can also passively hasten the process.
The cells at the base of epidermis (stratum basale) divide, start to mature and their membranes start to thicken. As new cells are formed, the existing cells move up and slowly their nucleus starts to shrink and the cells eventually die. The dead cells then form a layer (stratum corneum) right at the top. This layer is also called the “Horny layer” as the dead cells in this layer are more resilient than other cells, like that of an animal’s horn (I had a big smile on my face while reading about this, I don’t know about you :P). Desmosomes (cell structural component specialized for the cell to cell adhesion; basically cell glue) start to dissolve with naturally occurring skin enzymes till the cell to cell adhesion diminishes and the cell eventually sheds off2.
Thus, skin exfoliation is a natural process. It is called desquamation.
Generally, exfoliation in dermatology means accelerated desquamation by use of external forces.
2. Is it necessary to Exfoliate?
As we age, the rate of cell turnover changes. The rate of cell turnover is different in different areas of the skin as well. This table enlists the average skin turnover rate at different ages (depends on a lot of factors like metabolism, diet, lifestyle, diseases, etc., and varies with each individual so look at this as a wide picture):
|Life Phases||Rate of Desquamation|
|Kids||10 – 14 days|
|Teens||14 – 21 days|
|Young Adults||21 – 35 days|
|Middle-aged Adults||35 – 48 days|
|Over 50 years||48 – 72 days|
Exfoliation and ageing
The rate of cell turnover slows as our metabolism slows. The desquamation of dead cells in the stratum corneum becomes prolonged as new cells are generated at a slower rate. Also, with ageing, the desmosomes become denser and sloughing of dead cells becomes tougher. Thus skin can start to appear dull, dry, uneven in tone and texture. Some other factors and processes contribute to ageing as well. Change in the rate of skin cell turnover is just one of the causes and effects.
Acne & Exfoliation:
I discussed a few causes of acne in my previous post but researchers have not identified all causes of acne yet. What they have found out is that acne can affect the desquamation process. Acne usually affects the deeper layers of the epidermis and the dermis. Under normal circumstances, the cells take about 2 weeks to travel from the Stratum Basale to the top of the Stratum Granulosum. However, because of inflammation & acne cells surrounding cells die faster in the deeper layer and dead skin piles while desquamation slows down. Thus exfoliation can help speed up the recovery process3.
While physical and chemical exfoliation are different processes altogether, exfoliation can be useful for various reasons. There are also many limitations associated with it.
3. Chemical vs Physical Exfoliation
Physical exfoliation is not always harmful. It mainly involves using friction to quicken the desquamation at the stratum corneum. It can be useful to physically exfoliate your skin to remove the resilient dead skin on the top of the surface.
It’s important to keep in mind the word gentle while using physical exfoliators. The entire epidermis is as thin as a sheet of paper. Physical exfoliation may not be the best to heighten desquamation in deeper layers of the epidermis since the cells are still alive.
Being vigorous with physical exfoliators can irritate & over-exfoliate the skin. It can cause inflammation and stress out the skin cells. This method is not the best method to exfoliate for people with sensitive skin prone to redness and inflammation.
Physical exfoliation can be performed by various methods like using
Scrubs with abrasive particles,
Konjac sponges, Cleansing towels, Cleansing brushes, Cleansing pads,
My favourite way is drying my face with a cotton face towel, post-cleansing. I haven’t tried any cleansing brushes but if someone has a good experience with them, please do share. There is no independent evidence that Clarisonic does a better job at cleansing although.
There is a lot of talk surrounding microtears and physical exfoliation. Microtears are microscopic cuts caused by almost anything sharp. It is important to know that not all scrubs cause microtears. Most scrubs have unevenly shaped particles which cause micro-tears in the epidermis. This does not usually damage the dermis and epidermis turns over every 28- 35 days in an adult. Thus, micro tears do not cause any long term harm/scarring but using such scrubs can cause uneven micro-cuts which may lead to infection, inflammation and cause acne. Some scrubs may have rounded, even, and softer particles which may not cause micro-tears at all.
Chemical exfoliation involves the use of various actives, compounds, enzymes (basically chemicals) on the skin to exfoliate. Different chemicals have different properties and play different roles. I will go in detail about each in the upcoming post.
In general, various chemical exfoliants are used to penetrate to & through different layers of the skin, weaken the desmosomes, accelerate desquamation, increase the reproduction of keratinocytes(a type of cells), speed up the cell turnover, and cast off the dead cells. The expedited keratinization (increase in the reproduction of keratinocytes) increases the collagen layer4 in the stratum basale while thinning the stratum corneum. As a result, the skin appears brighter; it is more even in colour and has fewer fine lines. Also, there are fewer chances of the follicle (and pores) getting clogged by dead cells and the damaged skin from the active acne also turns over faster.
All in all chemical exfoliation can be pretty useful.
A mix of both types of exfoliation can prove to be beneficial for the skin if practised with restraint.
4. When should you begin exfoliating?
As discussed earlier, under normal circumstances our skin cell turnover does not slow down until the age of 25.
Thus, unless you have an underlying condition like environmental stress (pollution), lack of sleep, a stressful lifestyle, hormonal imbalance, poor diet, etc., that may contribute to premature ageing and other skin imbalances (like acne, hyperpigmentation, etc.), exfoliation isn’t necessary before the age of 25.
Please refer to the guide posted below to determine if your skin needs exfoliation.
5. Limitations of exfoliation
The stratum corneum and the acid mantle together form the skin barrier. Exfoliation expedites desquamation and can lead to thinning and disruptions of the layers of stratum corneum. It can disrupt the skin barrier and also lead to transepidermal water loss.
The stratum corneum (dead cell layer) plays a vital role in the protection of the living cells and structures beneath the surface from dirt, dust, environmental damage, microorganisms, mechanical & chemical trauma, and damage from UV rays.
As cells die they turn into Corneocytes. Imagine the stratum corneum as a brick wall where the cells (Corneocytes) act as the bricks. These sponge-like bricks (cells) hold moisture/water absorbing compounds called “Natural moisturising factors” between keratin(protein) microfibers and the surrounding cement, holding these cells, is made of lipids which include 45-50% ceramides, 25% cholesterol, 10-15% fatty acids, and other lipids5.
Also, the acid mantle – a film that sits right over the skin, made by a mixture of sweat and sebum, that helps to maintain a low PH and inhibit the growth of microbes (due to the acidic PH) may be damaged by over-exfoliation/ consistent use of harsh scrubs and cleansers.
The stratum corneum also helps provide UV protection, thus, exfoliation can make your skin photosensitive. An adverse impact in Fitzpatrick skin types IV & V can be seen if exfoliation6 is practised without proper sun protection. A large population of Indians fall under these skin types which emphasises the need for use of sunscreen with exfoliation and practising restraint while exfoliating.
There is also a discussion that damaged stratum corneum may decrease the efficacy of sun protection provided by sunscreens. It has been hypothesized that thin and damaged stratum corneum may keep from sunscreen particles binding to the surface of the skin and forming a prospective film over it. A damaged stratum corneum may also allow the sunscreen to penetrate into the skin and be absorbed into the bloodstream at a far greater level than the threshold set by the FDA7.
6. So, to exfoliate or not to exfoliate??
Do not fix what does not need to be fixed. If you are below 25 and do not have any preconditions contributing to acne/dryness/premature ageing, there is no need for you to start exfoliating, especially using chemicals and harsh scrubs.
If you are above 25 or are dealing with aforesaid conditions, exfoliation can be beneficial. Please remember to go gentle on your skin though. You absolutely do not need to add 4 acids, 2 cleansing brushes and one peeling agent in their routine. Please make sure that you are nourishing your skin barrier and repairing it as you exfoliate. Exfoliation is not harmful but over-exfoliation can be harmful.
I will talk about barrier repair in another post but it is very important to have a healthy skin barrier if you want your skin to look healthy.
7. Exfoliation and Sensitive Skin
A highly reactive skin prone to dryness, irritation, redness and breakouts is termed as sensitive skin. People with sensitive skin experience negative reactions even to substances that are well tolerated by most skins. With growing research, more ways to gently exfoliate are being developed. PHA’s are one example. People with sensitive skin should employ a skincare routine catered to managing their sensitivity and strengthen their skin barrier before they begin to practice exfoliating. Patch testing is also super important.
8. How to Identify Over exfoliated skin?
Over exfoliation and skin purging can seem similar. This post by u/avaale explains in great length about purging. Please check it out incase you are confused.
If you experience one or more of the following after exfoliation, there are chances that you have over-exfoliated your skin:
Skin has become dull instead of bright.
Skin is breaking out in places you never usually get acne.
Skin has become itchy.
Skin has become red and sensitive.
Skin has become extremely dry, tight and flaky.
Acne has become worse instead of healing.
Skin has developed spots.
In case you have over-exfoliated, there is no need to panic. As mentioned earlier, epidermis completely turnover in 28-35 days. Please stop using exfoliating products immediately. It would be best not to use many products when you are trying to repair your skin barrier as your barrier strength is compromised. If you do nothing and just apply sunscreen also, your skin will heal itself. Simplifying your routine, using a gentle face wash, and barrier repairing & healing products with Ceramides, NMF, fatty acids and skin lipids can help your skin heal faster. I will discuss this category in a separate post on moisturizing.
PICTORIAL REPRESETATION & GUIDE:
I hope this post covered most questions and information regarding exfoliation. In my next post in this series, I would like to discuss various treatments and ingredients. Do you think it would be helpful to make a separate post discussing each active/constituent separately and a summary post at the end, or a single lengthy post discussing all of them at one place?
Please let me know if I missed something by commenting below and please give me feedback on this post and series. I would really appreciate your views.