Where to buy persimmon soap in the UK: Boots, Holland & Barrett, Amazon or direct?
Persimmon soap is easy to search for and surprisingly hard to find on the UK high street. Here is where it is (and is not) sold, and how to avoid a...
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Kakishibu: a thousand years of Japanese persimmon tannin, from fishing nets to soap
Persimmon soap can look like a recent internet discovery. It is not. The ingredient that makes it work, kaki tannin, has been a working material in Japan for at least a thousand years under the name kakishibu. Knowing where it comes from makes it easier to judge which modern products are the real thing.
What kakishibu is
Kakishibu is the juice of unripe astringent persimmons (Diospyros kaki), crushed and left to ferment for one to three years. Unripe persimmons are almost inedible because they are packed with tannins, the same class of compound that makes strong tea and red wine feel drying. Fermentation concentrates them and turns the juice a deep reddish brown. The finished liquid is a natural preservative, water repellent, dye and deodoriser all at once.
Where it was used
- Fishing nets and ropes. Coated nets resisted rot and seawater for far longer. This is the oldest documented use, from the Heian period onward.
- Paper and umbrellas. Washi treated with kakishibu becomes waterproof and tough. It was used for umbrellas, raincoats, fans and the stencils for kimono dyeing.
- Wood. Sake barrels, house exteriors and furniture were finished with it. The colour deepens with sunlight, which is why old Japanese houses have that warm brown tone.
- Cloth and armour. Kakishibu-dyed cotton was worn by farmers and fishermen. Leather and lacquer components in armour were treated with it against damp and mould.
- Medicine and drink. Folk medicine used it for burns and as an astringent. Sake brewers used it to clarify the drink.
From preservative to deodoriser
The property behind all of these uses is the same: tannins bind to proteins, oils and oxidised compounds. That binding is what kills mould on a fishing net and what fixes dye in cloth. In the late twentieth century Japanese researchers began studying the tannin's ability to neutralise odour molecules, and in 2001 a research team identified 2-nonenal as the compound behind the distinctive body odour of older adults, kareishu. Kaki tannin was seen as a natural fit for tackling nonenal. Persimmon soap followed quickly and has been an ordinary product in Japanese pharmacies ever since. Our nonenal explainer covers the chemistry.
Why this history matters when you buy
- It is the extract, not the scent. A persimmon fragrance or a picture of the fruit adds no tannin. Look for genuine kaki (Diospyros kaki) extract on the ingredient list.
- A soap is not kakishibu. Kakishibu was concentrated by years of fermentation. A modern persimmon soap uses the extract as one ingredient in a cleansing base, so judge it as a soap, not as the traditional liquid.
- It has always been paired with something. Craftsmen mixed kakishibu with oils and lacquers. In a soap, tannin needs moisturising ingredients beside it, or it dries the skin. KAKIORA pairs it with glycerin and skin-softening emollients in a gentle, soap-free base for that reason.
Kakishibu today
Traditional kakishibu is still made in Kyoto, Nara and Gifu, and it has found new uses as a natural wood finish and textile dye outside Japan. The soap is its most widely used modern form. The idea is not new; the packaging is.
