fresh ginger root on scalp is an excellent astringent.slice it and rub scalp. also oil of rosemary/ marigold infusion is a great rinse youcan make on your own for dandruff.
oil of rosemary is very strong must be diluted or it will burn.
i always made my own/steep rosemary herb in a pot of water
for a good 15/20 minutes and bottle it use as a hair rinse..or add natural gylcerin to it as a very gentle shampoo. useon scaly eyebrows too, you will probably see it help within about 2 weeks to a month i bet. then rub the ginger root on it in between to keep it oil free/ youcan buy water soluble glycerin at most pharmacitical depts in stores for like about 2-3 $ a bottle
add about a cap or so to water. it makes a good facial mister too btw. mix a light gycerin and water mix put in mister and during day mist face and hair with it.