What are the common misunderstandings about storing bags?
This answer is a draft. It stays unpublished until legal review and source verification are complete.
How to store a leather bag is a question people ask in every country. In Japan there is an extra factor: homes here are humid, and the conditions inside your closet can decide how long a bag lasts. If you have moved here from a drier climate, the habits that worked at home may not work here.
Japanese homes and the conditions for mould
- Tokyo's annual mean relative humidity is around 60–70%, and in the rainy season (June–July) the monthly mean reaches roughly 75% (Japan Meteorological Agency, historical data).
- Mould is generally described as growing readily at 70% humidity or above and 20–30°C, and the back of a closet tends to be more humid than the room.
- Synthetic leather (polyurethane) undergoes hydrolysis, a chemical change driven by moisture that makes the surface sticky and then peel. It is generally described as starting within a few years of manufacture, whether or not the bag is used.
| Storage point | Reason |
|---|---|
| Stuff the bag (e.g. paper wrapped in non-woven cloth) | Keeps the shape |
| Keep it in a non-woven (不織布, fushokufu) dust bag, never plastic | Lets air through |
| Store on a middle or upper shelf, not the bottom of the closet | Moisture collects low down |
| Take it out of the bag and air it once a month | Prevents damp and mould |
| Keep dehumidifier packs (calcium chloride, etc.) from touching the bag directly | Leaking liquid causes discolouration |
[Verify] Check the humidity figures in the Japan Meteorological Agency's "Historical weather data search" (Tokyo, monthly normals). The timescale of hydrolysis varies by maker and material, so we have avoided a definite number of years.
Misunderstanding 1｜The original box is the best place
Cardboard absorbs moisture and then releases it inside the closed box. If you use the box, add a desiccant and open it regularly.
Misunderstanding 2｜A plastic bag keeps dust off
Plastic traps moisture. A breathable non-woven dust bag is the standard choice.
Misunderstanding 3｜Synthetic leather is tougher than real leather
Synthetic leather (polyurethane) resists water, but hydrolysis caused by humidity gives it a shorter life than real leather. Dry storage does not stop the process, but it can slow it down.
Misunderstanding 4｜Leather needs plenty of cream
Too much cream leaves the surface sticky and feeds mould. The basic method is a thin layer, after a dry wipe, tested first on a hidden spot. Cream cannot be used on suede or nubuck.
Misunderstanding 5｜Add a moth repellent and you are covered
Some clothing moth repellents (pyrethroid types, for example) can discolour synthetic leather, metal fittings and glitter. Check the "do not use with" section on the product label.
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Sources
- Japan Meteorological Agency, "Historical weather data search" — Tokyo, monthly mean relative humidity [気象庁「過去の気象データ検索」東京・月平均相対湿度]
https://www.data.jma.go.jp/stats/etrn/view/nml_sfc_ym.php?prec_no=44&block_no=47662
- Tokyo Metropolitan Bureau of Public Health, "Preventing mould" [東京都保健医療局「カビの発生を防ぐには」]
https://www.hokeniryo.metro.tokyo.lg.jp/kankyo/kankyo_eisei/jyuukankyo/indoor/kabi.html
- National Consumer Affairs Center of Japan, "Enquiries about deterioration (hydrolysis) of synthetic leather products" [国民生活センター「合成皮革製品の劣化（加水分解）に関する相談」]
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.
About this article
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.
Follow the care label and the maker's instructions for any garment, shoe or bag. For expensive or sentimental items, ask a specialist cleaner or repairer.
Sources
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