Value Village ／ Beauty
This answer is a draft. It stays unpublished until legal review and source verification are complete.
You will hear both: "hot water opens the pores" and "cold water tightens them". The answer that Japanese households have shared for generations is neither — it is lukewarm water (nurumayu). This article sets out the target temperature and what happens to your skin at each water temperature, which matters in Japan, where winter tap water can be very cold.
| Water temperature | Feels | What happens on the skin | Suitable or not |
|---|---|---|---|
| Around 20°C / 68°F (cold water) | Cold | Sebum tends to solidify and cleanser foam does not rinse away well. Blood vessels contract briefly, so skin only *feels* tightened; pore size does not change | Acceptable only for the final rinse |
| 32–35°C / 90–95°F (lukewarm) | Slightly cool | The range where sebum starts to melt (the melting point of sebum is roughly 30°C / 86°F). Dirt comes off and the sebum you need tends to stay | The basic washing temperature |
| 38–40°C / 100–104°F (bath water) | Warm | Sebum comes off easily, but moisture is also drawn out of the stratum corneum (the outer skin layer). Washing your face at this temperature in the bath tends to dry the skin | Avoid if you have dry or sensitive skin |
| 42°C / 108°F and above | Hot | The sebum film and the skin's own moisturising components (NMF and intercellular lipids) wash out. Causes redness, tightness and itching | Not suitable |
[Verify] The melting point of sebum (about 30°C) and the "20 rinses" guide are figures commonly given by dermatologists and the cosmetics industry. Check the relevant passages in the source documents before publication.
Pores do not open and close like muscles. The feeling that hot water "opens the pores" is just warmed, softened skin. Stripping too much sebum can, in fact, lead to dryness and excess sebum production.
Blood vessels contract briefly, so the skin only looks tighter; the actual pore size does not change. Cold water also rinses cleanser poorly, so it leaves residue behind.
The water pressure and temperature of a shower (around 40°C) are often too strong for the face. Dermatologists in Japan also explain: "Do not aim the shower at your face; use lukewarm water scooped in your hands."
It depends on how much sebum you produce and your skin type. If your skin is dry, water (lukewarm) alone may be enough in the morning. If your skin is oily, sebum produced overnight stays on the skin, so many people do better using cleanser in the morning too.
A cleanser only works when temperature, friction and rinsing are all right. However good the cleanser, scrubbing hard with 42°C water ruins the result.
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https://www.dermatol.or.jp/qa/
https://www.jcia.org/user/public/knowledge/usage
https://www.kokusen.go.jp/
⚠️ 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.
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