Pretty brides of many Asian countries and Middle Eastern countries as well as certain African nations love to sport henna tattoos on their hands during their wedding. Henna tattoos are not like permanent tattoos that you can get at a tattoo parlor. Henna is a natural dye that stains the skin temporarily and helps one sport intricate designs on their hands. You will find the Internet is full of henna designs and information related to henna color care. However, there are very few websites that offer information related to the science behind the henna stains. In this article, we shall discuss how does henna work and stain our skin. So, without much delay, let us get our facts straight.
What is Henna?
Lawsonia inermis or the mignonette tree are different names for the same flowering plant called henna. The name 'henna' is derived from an Arabic name 'hinna'. The leaves of this plant are used to dye skin, fingernails, hair and even leather or wool since the Bronze Age. This form of tattoo art is used extensively during festivals and celebrations, especially during weddings. The leaves of henna when crushed do not stain the skin. They will stain only after the release of lawsone molecules present in the leaves, after smashing them with something mildly acidic liquid like tea. Thus, henna leaves are dried and ground into a powder to make a paste of toothpaste-like consistency. This paste is applied on the skin or hair for staining. This dye is completely natural and has no side effects. Side effects if any, arise only when natural henna is mixed with adulterants like carmine, pyrogallol, orange dye, chromium, silver nitrate, etc., that help in altering the effect of henna stain on skin.
How Does Henna Work?
After the application of henna, the dye leaves a burgundy stain on the skin. The color of the stain depends on individual skin type and the amount of time that henna was allowed to stay on the skin. The color on the skin is due to the lawsone molecules present in the leaves. These lawsone molecules are more concentrated in the petioles of the leaves. As mentioned in the preceding paragraph, lawsone molecules are released only when the leaves are crushed with a mildly acidic liquid. Thus, many people trade henna in the form of powder that is made by drying, milling and shifting the leaves. When one needs to apply henna tattoos, the powder is mixed with lemon juice, tea or similar mildly acidic liquids. A thick paste is formed and used to apply intricate, detailed body designs. Few drops of essential oils like eucalyptus, Cajeput, lavender or tea tree are added to henna paste. These oils contain monoterpene alcohols that help in improving the staining characteristics.
Our skin is made up of a number of cell layers. The outermost layer of the skin is called stratum corneum. It helps keep away dirt and other infectious agents from the lower layers of the skin. This layer of skin is thick on certain parts of the body like palms and foot soles (especially the heels) and may be thinner on other parts like the ear skin. The stratum corneum is made up of keratin which also makes up for fingernails and hair. When henna is applied on your skin or hair, the lawsone molecule is small enough to penetrate the skin cell. It enters the columns of skin cells and does not bloat or spread out like a drop of ink would on a tissue paper. Thus, the stains remain sharp and clear, till the complete exfoliation of the upper layer of skin. Henna stains darkest on the cells that are in close contact with the dye and the skin cells farthest from the dye have lighter shades.
Where are Henna Stains Darkest on the Skin?
As I have already discussed, henna stains darkest on body parts with thicker layers of stratum corneum. This means that the top part of feet, soles of feet and palms are regions where henna stains the darkest. You will find henna stains very dark, nearly black in color on the feet. It may take about 3 to 6 weeks for the color to completely fade from the feet. When it comes to hands, when applied on the top of the hands, it gives a dark brownish shade. It may last for about 10 to 12 days. Henna applied on the palms, near the knuckles and fingers will stain a bit darker than the top of the hand. Here, the color won't wear off so soon and take about 15 days to completely fade. The best place to wear a henna tattoo is on the hands (palms and lower hand) and feet (top of the feet and soles). This is because palms and feet have about 50 layers of stratum corneum. This helps the henna molecules to penetrate deep into the skin and saturate the color completely, thus, imparting a darker stain.
Where are Henna Stains Lightest on the Skin?
Henna stains are lightest on the upper arms, ankles and lower back. Henna applied on the wrist and lower arm will stain light or dark brown in color. As you move further up on the upper arm, the color will be lighter and half the shade on your palm and feet. The color will fade quickly in about a week or so. Color on the shoulders, upper back, lower back as well as on the waist will be very light. This is because, these areas do not absorb more of the dye molecules. Also, these areas are oily and wet due to perspiration. Ankles too stain well, but the color has a brownish shade and remains for a longer duration. Apart from that, henna applied on neck and face, stain the lightest.
Why Does Henna Stain Darken with Time?
After removing the dried henna paste from your skin, you will observe that the color is orange initially. In about 48 hours, you will observe the color darkening into a deep brown or blackish shade, depending on your skin type. This is because, air helps to oxidize the henna stain and causes the color to darken. You can even apply something alkaline on your skin or try steaming to force the oxidation process. This will help give you a darker shade of your henna body art.
Why Don't Henna Stains Last Forever like a Tattoo?
Henna does not stain forever like a tattoo because, henna molecules actually stain only the upper, dead skin cells like the stratum corneum. These skin cells are shed and exfoliated on a daily basis. This natural process helps in exposing a new dead skin layer and getting rid of the old one. Thus, as the skin layer is exfoliated, the lawsone molecules are lost along with them. Thus, as the dead cells exfoliate, henna will begin to fade. If you have a cut, bruise or opening on your skin, and you apply henna, this stain will remain forever. This is because henna will stain the dermal layer and this layer does not exfoliate like the stratum corneum layer. In case of tattoos, the ink stains the dermal layer that makes them last forever. Therefore, make sure you do not apply henna over a cut or scratch on your skin.
As you can see, the science behind henna stains is not very complicated. If the paste remains in contact with the skin for a longer time, you will observe a darker color that remains for a longer time. Henna stains last for about 1 to 3 weeks on hands and feet and fade away within a week from areas such as chest, back, waist, etc. You should apply henna paste for about 6 to 24 hours for the stain to saturate into the skin pores. If possible, do not wash the area with water for about 6 to 24 hours after removing the henna paste. As the skin undergoes natural exfoliation, the henna stains will fade and disappear with time. Enjoy sporting new henna tattoos as and when you like. One thing is for sure, you will never be bored with the designs you choose as your temporary body art.