I found a few articles where people describe the method, but this one is from a Chinese source and most closely matches the recipe in the recent discussion:
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Source:
ejinsight on the Pulse
For one thing, they use rice water – the water after rinsing rice – together with natural ingredients such as tea seeds and ginger. The fermented solution is the Yao women’s shampoo.
This fermented rice water is rich in vitamin B, which promotes melanin production for the hair.
Tea seeds, which contain a high level of crude protein and a variety of amino acids, work as excellent non-ionic surface active agents that effectively lift and remove dirt from the hair.
This natural shampoo is believed to keep the Yao women’s hair shiny black and silky soft. It also has anti-dandruff, anti-itch, anti-hair-loss properties and helps in oil control on the scalp.
Interested readers want to make this natural shampoo at home.
Add rice water, orange peel (which could lighten the fermented smell of the shampoo), tea seeds and slices of ginger into a ceramic or earthenware container.
Close the lid tightly and see to it that the jar is at room temperature to allow for fermentation.
After around 10 days, the jar will give out a faint sour scent, indicating that the shampoo is ready for use.
Pour out some of the solution, but not too much, into a container and use it on your hair like a shampoo.
Gently massage the scalp and the hair to absorb the ingredients. Then rinse the hair with water after 10 minutes.
Add the same volume of rice water into the jar for another round of fermentation. The shampoo will be available for use as soon as it turns sour again.
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Source:
HKEJ Lifestyle Journal
But because they had the link the the Chinese version and the version wasn't complete, I did a google search and found the orginal Chinese text. Thanks to google translate, we have a bit more info.
The method is as follows: the first "washing rice water",
orange peel (rich in vitamin C and volatile oil, which can reduce the sour taste after fermentation of "washed rice water"),
tea seeds,
yao ginger into the altar, sand pot or In pottery utensils,
avoid using metal utensils. Close the bottle mouth and move it to the side of the fire to
keep the temperature at around 20 degrees Celsius.
About 10 days or so, the mouth of the jar overflows with a light sour taste, which can be used for shampooing.
The washing method is: pouring a small half of the pot of "washing rice water" from the altar, without mixing other water. Then soak the hair in the "washing water" and gently rub it to make the nutrients fully absorbed without using shampoo.
After about 10 minutes, rinse your hair with clean water.
Hair combing is also important for hair care. After shampooing,
gently rub the hair to 80% dry, comb with a thin ruler, start from the two corners and hair angles, comb the back occipital bones, loosen the hair, and gently comb the hair from the top for a few times. Or naturally dry.
It is advisable to wash twice a week. Note: After each take of the "washing rice water" in the altar, the same amount of "washed rice water" should be added, and the original temperature should be maintained. After a few days of fermentation, it can be used as shampoo. You can't take too much each time, otherwise the newly added "washed rice water" is difficult to ferment and become sour, which will affect the next use.
This is the symbol for
tea seed -- 茶籽
This is the symbol for
tea seed shampoo -- 茶籽 洗頭
This lady has a couple of videos about using tea seed powder to wash hair. She shows the brand that she uses (maybe it can be found in North America?) It's in the green bag.