Henna dyes the hair, skin, and fabric organically, similar to a black tea dye. This substance is extracted from a tree by drying and grinding leaves and stems. The greenish powder, when mixed with an acidic liquid, makes a temporary red, brown, or orange design on a porous surface. People use henna in ritual skin painting, called Mehndi, for birth and marriage celebrations, and Western cultures have adopted it to make temporary tattoos and organic hair dye.
The henna tree, Lawsonia inermis, grows in hot, arid regions like North Africa and India. For centuries, people ground the foliage of the plant into a powder to dye cloth and skin. The strong pigment, lawsone, actually temporarily stains the skin. It is a tannin, like those found in wine and tea. They infuse porous surfaces with a darker pigment, but do not chemically alter the surface permanently.
This dye works because lawsone is absorbed into material like hair and skin. People mix the powdered henna into a mud, using hot water, lemon juice, vinegar, or other acidic additives, which strengthens the dyeing properties. Users then apply the mud to a surface, like the palm of the hand, bottom of the feet, or anywhere on the body. They should leave the mud on for as long as possible, up to 48 hours. When it dries and crumbles off, the skin will have darkened to auburn, orange, red, or brown.
Depending on the fineness of the paste, some people apply henna with a tube, like icing a cake. With a lot of coordination and care, people can achieve intricate designs full of scrolls, swirls, paisley outlines, and dots. These tattoos can be used to create temporary bracelets, motifs, emblems, or words. In traditional Mehndi, Muslims and Hindus decorate the skin of those participating in special ceremonies, such as a wedding or circumcision, in places like Indonesia and India.
Dying with henna is entirely temporary. Hair dye may last up to six weeks, but skin dye will probably not stay visible for more than a week. This is because it has only sunken into the uppermost layer of dead and dying skin. When the skin flakes off through natural exfoliation, it will be gradually replaced by fresh, uncolored skin. Hair dye will also slowly fade away to the hair's original color, but will not leave any lines or stripes like synthetic dye.