Where Does the "Unabsorbed" Moisture Go?
How to Properly Fill Your Skin’s Reservoir
Our skin, specifically the stratum corneum, has a physical limit to the amount of moisture and ingredients it can absorb at once. Imagine a dry sponge: at first, it rapidly soaks up water, but once it is fully saturated, any additional water simply spills over.
Skincare follows the same principle. Even if you layer multiple products like cleanser, toner, serum, mask, eye cream, the surface of your skin eventually reaches its "full" capacity. Any ingredients applied after this point simply sits on the surface of an already saturated skin barrier.
Skincare is not always better with more layers.
The Science of the "2.7 mg/cm²" Barrier
A study by Teichmann et al. (2005) suggested that there is a definitive limit to the amount of substance the stratum corneum can store at one time. Through experiments on the forearms of subjects, the research found that the maximum capacity is approximately 2.7 mg/cm².
When converted to the average surface area of a human face, this is equivalent to about one gram, roughly the weight of a single 1-yen coin (*1). This highlights how surprisingly small the skin’s “reservoir” actually is. Notably, this maximum capacity remained unchanged even six hours later. In other words, waiting longer does not cause the skin’s "reservoir" to expand.
This research suggests that the size of our skin's storage is fixed. No matter how much time you spend meticulously applying products, the amount the skin can hold does not change. Ingredients do not "accumulate" just because they are applied repeatedly or left for a long time. The key is not the duration of the routine, but the quality of the ingredients delivered into that limited space.
The Hidden Risks of "Surface-Level" Hydration
In an effort to deliver more benefits, it is easy to fall into the habit of layering numerous products. This can create the sensation of well-moisturized skin.
However, in many cases, this is simply surface-level saturation, where moisture remains on the outermost layer, without effectively reaching the inner layers.
The real risk here is "Friction Stress." A routine with excessive steps means touching your skin over and over again. Even gentle actions, such as using fingertips or a cotton pad, can place stress on the stratum corneum when performed frequently.
As a result, steps that are intended to benefit the skin may, ironically, disrupt the skin barrier and accelerate dryness.
Therefore, rather than forcing ingredients into the skin, the goal should be to prepare the skin’s natural "reservoir" with minimal steps and deliver only what is truly necessary at the highest quality. This is a "wise choice" that minimizes stress on the skin and trusts in its innate ability to hold moisture. Beauté de Pivoine’s sincere approach to skincare maximizes the quality of each step to protect your beauty ten years into the future.
*(1) Based on an average Japanese facial surface area of approximately 400 cm²: 2.7 mg x 400 = 1,080 mg (approx. 1 g).