Value Village ／ Everyday know-how
This answer is a draft. It stays unpublished until legal review and source verification are complete.
Two cheap powders do most of the cleaning in many Japanese homes: sodium bicarbonate (baking soda, "jūsō") and citric acid ("kuen-san"). The approach is simple chemistry — match the cleaner's pH to the dirt — and it comes with one absolute rule about chlorine bleach.
| Dirt | pH of the dirt | Use | Do not use |
|---|---|---|---|
| Grease, food splatter, body oils, sour smells | Acidic | Baking soda (pH ~8) or sesquicarbonate (pH ~9.8) | Citric acid (does nothing) |
| Limescale, kettle furring, soap scum, urine scale, ammonia smell | Alkaline | Citric acid (pH ~2) | Baking soda |
| Mould | — | Neither reliably; chlorine-based mould remover, used alone, with ventilation | Any acid in the same room at the same time |
[Verify] The chlorine-gas hazard is documented in the Consumer Affairs Agency and Tokyo Metropolitan Government safety advisories on "mazeru na kiken" (do not mix) labelling.
The fizz is carbon dioxide from the two neutralising each other. What remains is close to salt water. The bubbles can help lift loose debris in a drain, but as a cleaner the mixture is weaker than either powder alone.
They are unrelated. Citric acid or vinegar added to chlorine bleach or a chlorine mould remover releases chlorine gas. Japanese chlorine products carry the legally required warning "Danger — do not mix" (まぜるな危険, mazeru na kiken). Use on separate days, rinse well between.
Poorly. For a spray, use warm water (about 1 teaspoon per 100 mL); for stubborn grease, sesquicarbonate dissolves better and is more alkaline. Wear gloves for prolonged use of either.
It etches marble and travertine, dulls brass, and can damage iron fittings if left on. Test, apply, wait 10–30 minutes, rinse thoroughly.
They handle most daily dirt. Mould, blocked drains and disinfection are where commercial products still do the job — used one at a time, following the label.
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https://www.caa.go.jp/policies/policy/consumer_safety/caution/
https://www.hokeniryo.metro.tokyo.lg.jp/anzen/ensokei/
https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/0000131034.html
⚠️ 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.
Always follow the instructions on any product you use, and never mix cleaning products. If you rent your home, check with your landlord before making any changes.
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