
Temperatures have already dropped below freezing, announcing winter's arrival. 🥶 Korea's winters are exceptionally dry.
With lower temperatures bringing less sweating and dry weather reducing skin moisture, making your skin rough and makeup tricky to apply. 🪞 Yet using 'peeling' and 'scrubs' to remove may not be a good approach.
Today, let's explore why flaking increases in winter and how to address it properly.
The Castle Wall Structure of Your Skin Barrier

Even if the explanation gets lengthy, we must start by understanding how your skin barrier is structured. 🤓
Our skin has two main layers: the inner dermis and outer epidermis.
The inner dermis is a complex of collagen and various components that maintain our skin's firmness and health. It's where blood vessels, immune cells, and all structural elements reside—a significant place.
In contrast, the outer epidermis is a collection of cells that produce keratin. 📐
📌 The Castle Wall Blocking Foreign Substances

Koreans have a sauna culture of scrubbing away "때" (ttae). Those white noodle-like strands that come off are actually clumps of dead skin cells. They look like waste and seem dirty. 🤣
But what if we had no keratin layer? Our skin would be exposed to extremely dangerous levels of foreign substances. Our kingdom's walls would be breached. 🏰
📌 Skin Barrier: A Wall Built with Keratin Bricks

American MD Peter Elias proposed the 'brick and mortar' skin barrier theory. Building our skin barrier is no different from stacking bricks to make a wall.

Here's the skin barrier structure. Though it looks complex, it's actually quite simple. 🪄
In the stratum corneum, brick-like corneocytes attach through corneodesmosomes—like stitching. Between these cells, the intercellular lipid bilayer (a membrane of organic compounds within living organisms) fills the gaps—like mortar!
Here, the bricks—the corneocytes—are literally the "ttae," the dead skin! But if you forcibly remove this keratin, you're literally breaking bricks and creating holes throughout the wall.
Factors Also Used as Cosmetic Ingredients

Over 90% of our epidermis consists of keratinocytes. Through repeated differentiation, they produce sturdy bricks for the construction of the skin barrier. During this cell process, critical protective components are also produced.
📌 Natural Moisturizing Factors That Retain Water
During cell progress, countless keratin filaments form. These are bundled by a protein called filaggrin to create solid structures. This complex process also generates NMF (Natural Moisturizing Factor)—a substance that firmly grips moisture.
NMF, which maintains keratinocyte stability by holding water, is commonly seen in cosmetic ingredients!
📌 Oil Glue Binding the Bricks Oil Glue
Keratinocytes also contain lamellar bodies. Simply put, think of them as oil, lubricant, or glue. If keratinocytes are the bricks of the skin barrier, they are the mortar that fills and secures the spaces between the bricks. The largest component of this factor is ceramide, also a well-known ingredient in cosmetics and moisturizers.
To protect the skin barrier, mindlessly removing its bricks—the 'keratin'—may not be the right approach.
Therefore, strong moisturization and avoiding direct exposure to cold air are better approaches. 🧣
The skin barrier acts as the skin’s frontline shield. While thick layers may occasionally need gentle exfoliation, the best approach is keeping this protective layer healthy through consistent hydration. 😎