Cover the bowl with plastic wrap and let the paste sit until dye release is achieved. You’ll know the dye has been released when the surface of the paste turns brownish (as opposed to the original greenish color when you started).Add your “terp.” Terpines are hydrocarbon solvents that release and darken the henna. Tea Tree, Cajeput and Ravensara are the most common terp choices. Aromatherapy grade oils are safest for the skin.Re-cover the henna paste and refrigerate until ready to use (or freeze if you won’t be using it within a few days).
Prep the Henna Paste

Strain your henna paste to remove lumps by placing a nylon stocking over a cup and spooning the henna mixture into it.Pull the stocking out of the cup and put the toe-end, full of the henna paste, into a carrot bag.Gripping the bag tightly with one hand, pull on the end of the stocking with the other hand so that the henna is squeezed out.Pull the stocking out and the henna should be inside the carrot bag, smooth and ready to use.Snip off the end of the carrot bag and squeeze the paste through the bag into a 1 ounce applicator bottle (see Resources below to purchase applicator bottles made especially for henna application).