Value Village ／ Beauty
This answer is a draft. It stays unpublished until legal review and source verification are complete.
Dry skin is a shared complaint the world over, but the usual response leans towards "adding" more moisture. Japanese skincare has a well-known layering habit, and one measure from dermatology explains why the order matters. Once you know it, the routine changes.
Quite apart from sweat, a small amount of water evaporates constantly through the stratum corneum (the outermost layer of skin). This amount is called transepidermal water loss (TEWL), and the lower the value, the stronger the barrier function of the stratum corneum is generally described to be. It is used both to assess dry skin and in cosmetics testing.
Moisturisers work in two ways.
| Type | Action | Examples |
|---|---|---|
| Water-based | Holds on to water | Glycerin and similar |
| Oil-based | Forms a film on the skin surface and physically blocks evaporation | Petroleum jelly (ワセリン, waserin) and similar |
"Adding" alone does not change how much escapes. The order is: add, then seal.
[Verify] The explanation of TEWL is based on the SCCJ glossary and on pharmaceutical-company material for healthcare professionals. Confirm before publication.
The water you apply evaporates. In Japan the watery first step is called *keshōsui* (化粧水, "lotion" or "toner"). The step that follows it, sealing with oil, is what does the work.
A cleanser that is too strong puts a load on the skin's surface function. Review how you wash before you review what you apply.
Air-conditioned rooms, UV exposure and evaporating sweat mean there are causes of dryness in summer too. Japanese summers are humid but heavily air-conditioned indoors.
Hot water is generally described as tending to strip away sebum the skin needs. Lukewarm is the guide.
Indoor humidity, bath temperature and friction from clothing are also involved. If itching or eczema persists, see a board-certified dermatologist at a dermatology clinic (皮膚科, hifuka; covered by Japanese health insurance).
---
https://www.sccj-ifscc.com/library/glossary_detail/487
https://www.dermatol.or.jp/qa/
https://www.mhlw.go.jp/file/06-Seisakujouhou-11120000-Iyakushokuhinkyoku/kesyouhin_hanni_20111.pdf
⚠️ Editorial note: the source URLs above were identified by search. Our working environment cannot reach go.jp domains, so the contents have not been checked against the text. Verify every source before publication and record who checked it and when.
What we share here are ideas and everyday practices passed down among people living in Japan, together with general information drawn from public sources. They are not official recommendations, and they are not professional instruction. Practices vary between households and regions.
This is general information. Results vary from person to person and depend on your own conditions and surroundings.
Please decide for yourself, using your own judgement, whether any of this suits your situation. We cannot accept responsibility for any damage, loss or injury arising from following this article.
Cosmetics are not medicines and are not meant to diagnose, heal or prevent any condition. If your skin reacts, stop using the product and see a dermatologist.
Tell us if this has changed
Approved contributions keep the contributor's name, shown in five languages.
Other languages：日本語 ／ 简体中文 ／ 繁體中文 ／ 한국어
Value Village is not a government body. Always confirm procedures on the official site.
Written by Value Village from public sources. Nothing here is reproduced from another site.