In addition to the crushed henna leaves, the basic ingredients of henna dye are sugar, lemon juice and essential oils, such as lavender, eucalyptus and tea tree oil. Strong tea is sometimes used instead of lemon juice, while henna artists may add sugar for its adhesive qualities. Other ingredients added to the mixture in African countries include lime, clove, okra and pomegranate.
How henna paste is applied to human skin varies according to the country you're in. In Africa, for example, henna artists add saliva to the henna powder, which is then rolled into balls and applied using such implements as twigs or wire. In Morocco, syringes are used to apply the paste, while artists in India prefer to use a plastic cone. Henna is also available in small plastic bottles.
Since henna has been utilized for skin art all over the world, it's difficult to pin down its exact origins. Historians suggest it may have been used in 2100 B.C. by the Syrians, while evidence exists of its use a few hundred years later in such places as Greece, Egypt and India. Henna use has been linked for centuries to religious worship and has long been applied to the bride and guests, particularly children and women, at marriage celebrations in such countries as India.
The length of time henna designs stay on the skin depends on how long the paste is left on and the thickness of the skin it's applied to. Designs will last longest if the paste is left in place for eight hours or more. The hands and feet, areas with relatively thick skin, are the most suitable places for long-lasting designs, with the henna lasting one to two weeks or more. In thinner-skinned areas, such as your chest and back, the designs last three to 10 days.
The color of a henna design can vary. Typically, after removing the henna paste, the design left behind will be somewhere between an orange and a dark red-brown. The color will vary depending on your skin type, how long the paste is left in contact with the skin and where it is placed.