Value Village ／ Beauty
This answer is a draft. It stays unpublished until legal review and source verification are complete.
Many people use a straightener or curling iron every day, and two questions keep coming up: "What temperature should I set?" and "Is damage just unavoidable?" Here we look at how the protein in hair behaves under heat, and at the burn accidents reported to Japan's consumer-safety bodies every year. There is also a note on using a hair iron bought abroad in Japan.
| Item | Detail |
|---|---|
| Heat tolerance of hair | Keratin denaturation progresses above about 150°C; above 200°C the damage to the surface (cuticle) is marked |
| Recommended settings | Fine or damaged hair: 120–140°C; normal: 140–160°C; thick or coarse hair: 160–180°C. 200°C and above is for brief salon techniques |
| Contact time | 2–3 seconds per section; do not repeat the same spot. One quick pass beats one slow pass |
| Wet hair | Never. The water inside turns to steam suddenly and the "steam explosion" hollows out the inside of the hair. Dry completely first |
| Protection | A thin layer of hair oil or milk labelled heat-protective. Too much scorches under the heat |
| Burns | Plate temperature is around 200°C. Contact burns to the face, ears and neck, and children touching the device (NITE, Consumer Affairs Agency). Rest it on a heat-resistant mat after use; do not pull the cord |
| Auto shut-off | Many models switch off after a set time. Without it, forgetting to switch off is a fire cause |
[Verify] Check the keratin denaturation temperature against standard hair-science texts, and the accident cases against NITE and Consumer Affairs Agency materials.
Denaturation progresses above 150°C and damage is marked at 200°C. One quick pass at 140–160°C does less harm.
Heat on wet hair hollows out the inside through a steam explosion — the most damaging way to use an iron. Dry completely first.
A thin layer of oil labelled heat-protective. Too much scorches and turns greasy.
Damaged hair does not regenerate. Iron-free days and lower temperatures are the only prevention.
A 200°C plate stays hot for several minutes. Cool it on a heat-resistant mat, out of children's reach, and check whether it has auto shut-off.
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https://www.caa.go.jp/policies/policy/consumer_safety/child/
https://www.nite.go.jp/jiko/chuikanki/
https://www.meti.go.jp/policy/consumer/seian/denan/
⚠️ 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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