Indigo powder is a natural dye which is very famous now days for coloring hair black. Many people know it as black henna, but it gives a blue dye. When used with natural henna powder it gives a dark brown to shiny black color. Generally it gives a blue dye even though it looks just like henna. It is also used to dye clothes and get a denim blue color. In botanical language it is known as indogofera tinctoria. The indigo powder is made using the leaves of indigo plant. How to use: mix henna powder in a bowl with water and a bit of acid, like lemon juice, vinegar or orange juice. Add enough liquid to make it the consistency of pudding. Cover the container with plastic wrap and let it set you see dye release. Once the henna has dye released, in a separate bowl, mix up the desired amount of indigo powder with warm water. Stir until the lumps are gone. Add the just mixed indigo to the henna paste and stir together until well mixed. Immediately apply to freshly washed hair. You may need to add more water as you are working with the paste, as it will thicken as it sits. Wrap head in plastic wrap, and then place a shower cap over the top of that. Allow to sit on hair for a minimum of 2 hours. Rinse paste from hair. Do not shampoo for 24 to 48 hours, as the henna/indigo will need time to oxidize.