Henna changes color as it dries - it starts out looking greenish brown and dries into a dark brown. This paste flattens as it dries and the natural dye molecule seeps into the layers of skin for several hours. The photo below shows the art in progress, I still have a lot of spots to fill in.
And here is the completed henna design, a kind of bouquet that similar to the zentangle style.
I love to see families celebrating together like this! This sweet little boy is just 16 months old. Henna stains everyone's skin a little differently, and I love the shade it got to in this image.