MIMF

I was doing some googling on finishes today and came across a reference to a traditional Japanese product called kakishibu. It is the juice of unripe astringent persimmon fruit and has multiple uses: from folk/herbal medicine, to textile dye, to a wood preservative treatment. (That "astringent" part is very important, as there are apparently many, many varieties of persimmon, and the most astringent are desired for high tannin content.)

The dye is a sort of rusty red, but it also imparts some sort of preservative quality. One website I found says, "Persimmon tannin hardens the fiber of wood and paper, prevents corrosion, and makes them waterproof. It has been used to make Japanese paper, umbrella, and wooden wear such as wooden cups." http://www.kakishibu.co.jp/home/sibu-e.html

Most of the websites I found were about paper and fabric, and I couldn't really find anything specifically about a wood product. This company, out of Colorado, sells the dye http://www.kakishibui.com/index.html.

Anyone have any experience with this stuff? What is the actual effect of adding tannins to wood? If the "hardening" or "preservative" qualities are questionable, it could at least be an interesting, natural dye.

I've never heard of it but it seems a cool product to try out.
I doubt if the product would really strengthen the wood, but it may be a good natural (as in "from nature") product.