Soak enough henna powder in water to make a thick paste. Leave paste overnight. Next morning, or just a couple of hours later, apply, giving specific importance to the ends of your hair. Wash off after three to four hours. Henna is one of the oldest hair colors and can give some remarkably beautiful lights even to black hair. On hair that is almost black, black henna gives deep ripe-black plum lights. It also gives a 'fire-down-below' gleam like polished rosewood, to drab brown hair.