Add arrowroot powder to a small mixing bowl.
Using a measuring spoon, start by adding a tbsp at a time (for dark hair) or a tsp at a time (for light hair) of cocoa powder. Then, stir it in, adding more if needed depending on your hair color.
If your hair has a reddish tint, add a pinch of cinnamon with the cocoa powder. Start with less and add more until you reach the desired color.
Transfer to an airtight container for storage.
Divide hair into sections.
Dab powder onto the roods of the hair and let sit for 1-2 minutes.
Starting at the roots, use your hands to work the powder into the scalp and down to the tips of the hair.
Brush any extra powder out before styling like normal.