Sorry this took a bit longer to get completed but lots of you have asked recently how to use henna and indigo powder to darken those reds up a bit or go black and it's really easy.
Thing you must remember about using indigo is that under no circumstances can you freeze the powder. If it's frozen it will not give you the results because the cold renders the dying ability useless so don't freeze indigo powder or paste.
To go dark brown you will prepare henna as usual, once you have dye release you mix indigo with enough water to make a paste that is about the consistency of yogurt (to 100 grams use about 25 grams of indigo) wait about 5-10 minutes for the paste to change color then add it directly to your henna paste.
Apply as usual remembering to try not to keep the henna on for more than 4 hours to avoid drying. Cover with heat cap, plastic wrap, plastic bag or for an extra nice treat sit under the steamer!
Rinse well with warm water until your water runs clear- may take a while so be patient!!
To go black you will apply the henna to hair first, leave on for the usual 4 hours and rinse well. Mix your indigo powder to make a paste, allow it to sit 5-10 minutes and then apply the indigo paste to hair (you can cover it with the same thing you covered your henna hair with:) DO NOT LEAVE INDIGO IN FOR MORE THAN 2 HOURS!
Indigo is extremely acidic and lots of people get scalp itchies after using, a simple fix is to just rinse hair with aloe vera juice or even a baking soda rinse will quickly solve this issue. Stubborn grays- my long term henndigo queens say add a pinch of salt to your paste to keep hair color longer!!