What is Henna?
Natural henna powder is derived from a henna plant which is scientifically known as Lawsonia inermis. The plant is a shrub with small leaves and fragrant flowers. The leaves of this plant are dried and grounded and the powder derived from it functions as a natural reddish dye. The powder is mixed with other oils and liquids such as clove oil, eucalyptus oil, and lemon drops. Things such as vinegar and lemon juice act as mordant and oils such as lavender oil and eucalyptus oil acts as terpenes. The quantity varies from region to region and henna powder to henna powder.
Henna paste needs to left on skin for 4-8 hours so that the dye can stain the skin. After the dye has dried and scrapped off, it leaves back an orange color stain, which later darkens to reddish brown or burgundy color. This is the reason why the stain should be kept away from water for 24 hours and the area needs to be provided with warmth. The intensity of the color and the time taken for fading of henna dye depends on skin chemistry of the region of the body where the henna is applied. The color is absorbed by the top layer of the skin. Usually henna stain lasts for 2-3 weeks until the top skin layer turns into dead cell and is exfoliated. The henna stain imparts a darker color and stays longer on the palm and sole and shortest on upper arm, chest and back. Henna can clog if the particles aren’t fine. To deal with this problem the henna powder need to be sifted.
Because of this dyeing property, henna is also used to dye hair. Apart from dyeing, it also acts as a great hair conditioner. The color imparted by henna to hair depends on the base color. White to blonde hair results in a bright color and brown to black hair results in a burgundy color.
Nowadays, henna is being mixed with debris, dye and other plant material. Dye is added to bring a greener and better appearance to the henna powder. To recognize any foreign material, samples of wet henna can be placed on microscope slides. When they are rubbed together a gritting sound will be produced because of mineral debris or sand. Henna which has a bright green color is polluted with dye. The local sand is finely ground and dyed with auramine yellow and diamond green, which is then added to pure henna powder. Mryobalan, a dye plant, is also added to pure henna powder and the mixture imparts a redder henna color. Sand, grit, mryobalan, auramine yellow dye and diamond green dye are harmless. But if the quantity is more, it means the person is cheated into buying less henna powder and more waste.