Here is the indigo vat recipe that I have been working with written by Earth Hues. They are a wonderful company supporting agriculture, natural color and artisans around the world. I order my pigment from them and every time I order, I ask where the pigment is from. Most of the time the pigment has been from El Salvador. This is the recipe they provide and it's fantastic!
Woad was grown and picked in its first year. Leaves were chopped up, made into balls and left to dry until they hardened. The dried balls were broken into a powder, sprinkled with water and allowed to ferment, known as couching. When the couched woad dried. Hot water is poured onto the couched woad in the vat, adding potash or urine. This mixture would ferment for days before the dyebath is ready.
blue & white
I took a class from an indigo blue dye master when we were in Japan. This is the same classic technique.
Indigo dye - Japanese traditional method Ita-Jime
fabric dyed with rusty pins, onion skins, roses, eucalyptus and vinegar.