A dark stain begins with Fresh Henna.
Ok so it's really 5 steps. Before everything else, you'll need to get your hands on some fresh, natural henna powder from a reputable henna supplier. May we humbly suggest our tried and true henna paste recipe here.
Patience, Young Grasshopper:
Step one: the henna paste is applied to clean skin that is free of any oils or lotions.
Step 2: Once dry, the henna design is sealed with a sugar solution (we use sugar and water in a misting bottle). The stickiness of the sugar keeps it, well, stuck to you. The longer it remains in place, the better. A minimum of 6-8 hours is recommended. Traditionally henna is left on overnight. You can gently wrap your mehndi in tissue to keep it in place. Avoid cling-wrap, which can cause sweating.
Step 3: After 6-8 hours (or overnight), gently pick off the henna paste, or rub it off with a paper towel. Never wash it off or you will halt the staining process. It should be a bright orange color when you pick it off.
Step 4: Avoid water for an additional 12-24 hours. If this is not possible, generously oil your design with coconut oil, shea butter, or any other greasy vegetable-based oil. You will see your design start to darken as it oxidizes throughout the day. Natural henna requires about 24 - 48 hours to reach its darkest point. The stain will always be darkest on the palms, where the thicker skin can absorb more henna, and lighter toward the thin skin of the wrists and arms for a beautiful ombré effect.