Exfoliating is an old topic, some people say to exfoliate more, otherwise, the skin will be rough and the skincare products will not be absorbed; some people say don’t exfoliate too much, it will damage the skin barrier.
Today we will talk about how to exfoliate scientifically.
What is the stratum corneum?
What we call the stratum corneum is the outermost layer of the skin epidermis. Epidermal cells are produced from the deepest part of the epidermis (the basal layer), and they are pushed out layer by layer until they reach the outermost layer of the epidermis (the stratum corneum). It turns into dander and falls off naturally. Too thin stratum corneum can cause skin sensitivity, but too thick can cause dull and rough skin.
What is the function of the stratum corneum?
The stratum corneum is like a brick wall structure of a house. The bricks are the keratinocytes, which are about to die and fall off, and are especially capable of absorbing water. The cement between the bricks is a lipid, and the structure of ceramide + cholesterol + free fatty acid is tight and airtight, and the water is difficult to penetrate, can withstand external physical and chemical damage.
Why exfoliate?
The stratum corneum is the main part of the skin to absorb external substances, accounting for 90% of the total absorption capacity of the skin, under normal circumstances, the water content of the stratum corneum accounts for 20%-30% of the skin is the key to moisture retention. But as we aging, the metabolic cycle slows down. When the water content of the stratum corneum resists 10%, the skin will appear dry and desquamated. Dry skin is not only dull and rough but the absorption of water-based skincare products will also be weakened.
How to exfoliate?
Exfoliation is the use of physical or chemical methods to remove the outermost layer of the stratum corneum. Why does the stratum corneum metabolize by itself and do we have to exfoliate. That’s because, in addition to being older and slowing down metabolism, various circumstances such as external stimuli and one’s pressure can also cause changes in metabolism. Therefore, proper artificial help is needed to help it peel off.
Frequency of exfoliation
When you feel the skin rough, dull, lackluster, and skincare products are always poorly absorbed, then you need to exfoliate. For healthy oily skin up to 1-2 times a week, for problematic skin, avoid or extend the exfoliation time.
What are the ways to exfoliate?
Physical exfoliation
The skin is rubbed by scrub particles. These exfoliating products contain tiny scrub particles, which use the friction force between the particles and the keratin in the product to take away the excess stratum corneum. The principle is the same as that of toothpaste to clean the teeth.
Common exfoliating particles: brown sugar, salt, plant husk, synthetic materials(PE granules), oatmeal, silica, sodium bicarbonate, corn cob meal, peach seed powder, etc. However, avoid the use of large-grained coarse abrasive products.
Advantages: easy to use, quick to take effect, suitable for general skin types.
Disadvantages: may aggravate acne or skin sensitivity.
Chemical exfoliation
Alpha Hydroxy Acid or enzyme products help exfoliation of the stratum corneum. The principle of acid exfoliation is to break down the connections between cells and let the stratum corneum fall off.
Common acids are Alpha Hydroxy Acid and salicylic acid, and alpha hydroxyl acid is more recommended. Salicylic acid is sensitive to allergies, and its penetrating ability is not as good as alpha hydroxyl acid. It can only act on the keratinocytes on the surface. A low concentration of 2%-10% AHA can assist in keratin renewal.
Advantages: it can clean pores deeply, has a certain anti-aging effect, and is suitable for oily skin and acne-prone skin.
Disadvantages: easy to cause skin allergies, irritation to dry skin.