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What is Henna?
Henna is a small tree with the botanical name Lawsonia Inermis. The leaves contain the tannin lawsone, which is the only known dye particle small enough to penetrate a human cell. The leaves are collected when they are new young growth, as they contain high amounts of lawsone. They are then dried, and ground into a very fine powder. Good quality henna powder is bright green,
and has a short shelf life if not stored properly. Often, large companies selling henna will mix green hair dye or green sand in with the henna powder to make it look fresher.
Body art quality henna powder is made only from the leaves, with the stems and buds removed, and is ground very fine. It has been stored away from light, air and heat, often in a freezer. It is ground very fine, to a soft green dust, to allow fine intricate designs to be made from the henna paste.
How does henna stain the skin?
In the henna paste, are small molecules of the tannin lawsone. While the henna is wet, the lawsone can migrate from the paste into the skin cells. This dye penetrates the skin cells in the epidermis. It filters down into the layers of skin like ink on corrugated cardboard. The longer the paste is wet against the skin, the more time there is for the henna to penetrate deeper, and hence give a richer longer lasting stain.
The henna stain is actually many layers of transparent cells. It is not opaque, but appears to be because there are so many layers. At the top, where the skin is closest to the paste, the lawsone saturation is the highest. As we go deeper into the stratum corneum, the lawsone levels are less, and the oxidation is less.
The color of the stain begins as a bright orange, as the dye sits around waiting to oxidize. As the stain develops the lawsone goes through an oxidation process, and you can see the stain darkening before your eyes. This process usually takes about 12-24 hours. The highest lawsone or dye saturation is near the surface of the skin, this is also where the most oxygen is available for the oxidation process. As the stain fades, new layers of skin cells are moving to the top, and the cells with less lawsone and less oxidation come to the surface. This is why the stain lightens back to orange as it fades.
Once the paste is removed, no more lawsone can enter the skin, and the stain will not get any darker. The stain begins its oxidation process as soon as the paste is removed and the oxygen hits the skin. After it has fully developed, the skin cells begin to flake off, and the stain starts fading. This is why we recommend 24-72 hours in advance for appointments, so that your design will be at its peak color during your special event.
What colors does henna produce?
Henna comes in a wide range of shades of reds and browns. The color is affected by many factors, including body heat, climate, and skin chemistry. This image shows the range of henna colors most commonly achieved by natural henna on a variety of skin tones.
Ranging from blackberry to apple to a barely perceptible tan, natural henna can create many tones.
Natural henna, however, does not come in colors such as blue, black, green, purple, etc. Be wary of hennas that claim to be other colors than shades of red and brown. See 'The Dangers of Black Henna' for more information on colored henna and why it should be avoided.
Where does henna stain and why?
As seen above, henna stains the layers of dead skin cells on the surface of our epidermis. We have these same type of cells in our hair and fingernails also. These dead cells have keratin in them for the lawsone to bond to.
The body map below shows approximately where the darkest and lightest henna stains are achieved. The darker the stain, the longer it will last generally speaking. This is because it has gotten dark by staining more layers of skin, so it takes longer for all of those cells to be replaced.
Fingernails and hair are dead cells, they only grow at the roots or the matrix. So once these cells are stained with henna, it is permanent. The stain will not fade or be replaced by new unstained cells. Fingernails do not seem to oxidize as well as the hair and skin, and tend to be more orange.
Henna has been used on the palms of the hands and the soles of the feet in many traditions and cultures, because this is where the best stain is achieved.
Making Henna Paste
When henna leaves are crushed to a powder, the cells of the plant are broken open, making more of the tannin lawsone available. Henna powder is mixed with an acidic liquid to form a paste. Often lemon or lime juice is used. The acid in the liquid helps to further break down the cellulose of the plant cells, releasing more lawsone. The chemical breakdown of the cellulose takes time, and the paste needs to sit for a time. This chemical reaction happens more efficiently if there is heat available, so a warm place is good for the paste.
Once the paste has released as much lawsone as possible, monoterpene alcohols are added. Lawsone is a hydrophobic molecule, meaning it is repelled by water molecules. The cellulose that has broken down has left plenty of water molecules in the paste. Monoterpene alcohols are hydrophilic, meaning they attract water molecules. So by adding the monoterpene alcohols we are taking water out of the paste, hence making even more lawsone available for the amount of paste we have. Monoterpene alcohols are found in several essential oils, such as lavender, cajuput, and tea tree.
Sugar or honey is often mixed into the paste. Sugar is a humectant. It pulls moisture out of the air. This helps to keep our paste moist longer on the skin, helps it to bond and stick to the skin, and hence gives the lawsone more time to migrate from the paste into the skin cells. This results in a darker, deeper and longer lasting stain.
Aftercare and Tips
Once the henna design has been applied to your skin, it is important to take good care of it to ensure a great stain. While the henna is staining the skin, and just after it is removed is a crucial time in determining the color and length of the stain.
Let the henna paste dry naturally. Drying it out too fast will result in a lighter stain. Leave it on the skin for as long as possible, over night is best. Try not to remove the henna before it is falling off. When the henna is dry enough to flake off the skin, it has done its job and can be removed, up until that point is still staining.
When the past first comes off the skin, the design is bright orange. It will gradually darken and oxidize over the next 12-24 hours. While it is still orange, the dye is on the surface of the skin and can be washed away. It is important not to get the design wet during these first 12-24 hours. Getting it wet during this time will make the final stain come out lighter, and the design will not last as long.
To preserve the design as long as possible, protect the layers of skin from flaking off. Do this by avoiding anything exfoliating, do not scrub the area or use a heavy or anti-bacterial soap on the design. Use oil or lotion before bathing to help protect the design, and if it is on your hand wear rubber gloves when cleaning.
Chlorine in a swimming pool or hot tub will make the design fade quickly. Saline solutions, such as used for contacts, will also fade the design. If you need to remove the design, you can use the previous methods or try hydrogen peroxide or a whitening toothpaste. Be careful though, as applying bleach or chlorine to the skin is dangerous, and the whitening toothpaste is abrasive also and is removing layers of skin. Do this at your own risk, we assume no liability should you hurt yourself. Use common sense, and if it hurts, don't do it.
The Dangers of Black Henna
There is a difference between real, natural henna, which comes from the henna plant Lawsonia inermis, and the dangerous black dye that people are adding to henna to make black temporary tattoos. This fake henna can hurt you! Please make an informed choice for your safety and health, and help us keep the name of natural henna from being exploited.
"Black Henna" isn't really henna. There is no such thing as a black henna plant. Real henna only comes in shades of earthy-red tones. A design applied with a black inky looking paste and results in a near immediate black stain is most likely a chemical hair dye like paraphenylenediamine (PPD), a coal tar dye and known transdermal toxin. PPD and similar dyes, found in leather and fur dyes as well as commercial hair dyes, can cause itchy, oozing, blistering skin and long term scarring. In worse cases, organ damage results, along with permanent sensitization to even minute amounts of these chemicals. PPD is also a known carcinogen and is especially dangerous to pregnant or nursing women and children.
Instant Brown Henna: The newest imposter on the boardwalk! Right color, but ask first! Some unscrupulous people are adding brown hair dye to their henna, or even using straight brown hair dye on skin to avoid the warnings about black dye.
This, like the fake black henna is a chemical dye, with the same nasty side effects. These designs will appear brown immediately, not needing time for the color to darken.
Always ask your artist what is in their paste, and what color to expect when the paste is removed. Red /brown tones are the color of a natural henna stain. Natural henna will always appear orange at first and darken to a red/brown or burgundy color one to three days after application to the skin. Quick staining henna: It can happen, but ask first!
If the artist says you can remove the paste in just one hour be cautious. Ask what color the stain will be after removal. If the answer is orange, it is natural henna. If the answer is brown or black, there is something added to the paste, usually hair dye. Avoid it! Real henna stains always start out orange.Natural henna
- Always results in an orange stain that darkens to brown/red in one to three days.
- Needs to be kept on the skin as long as possible. Three to four hours is good, longer is better! If your artist says 'only an hour', ask what color the stain will be at first. You want to hear 'orange'.
- Henna Paste should appear green, brown or dark khaki and has a smell like musky hay. Sometimes you will smell essential oils like eucalyptus, tea tree, or clove oils.
- Is cooling and healing to the skin.
Dangerous chemical products sold as 'henna'
- Results in a black or brown stain immediately upon paste removal, with no color change over time.
- Only needs to be left on the skin one hour. If your artist says you can remove the paste in one hour, ask what color the stain will be. If the answer is brown or black, it's not natural henna.
- Paste can appear gray, brown or black. There may be no odor, or a chemical odor.
- Are damaging to skin and other body systems. Itching, blistering, scarring, organ damage and permanent allergies can result.
Choose wisely. Choose natural henna.
The information below is an excerpt from this FDA site
http://vm.cfsan.fda.gov/~dms/cos-tatt.html
Since henna typically produces a brown, orange-brown, or reddish-brown tint; other ingredients must be added to produce other colors, such as those marketed as "black henna" and "blue henna." So-called "black henna" may contain the "coal tar" color p-phenylenediamine, also known as PPD. This ingredient may cause allergic reactions in some individuals. The only legal use of PPD in cosmetics is as a hair dye. It is not approved for direct application to the skin. Even brown shades of products marketed as henna may contain other ingredients intended to make them darker or make the stain last longer.
In addition to color additives, these skin-decorating products may contain other ingredients, such as solvents.
How do I know what's in a temporary tattoo or henna/mehndi product?
Cosmetics including temporary skin-staining products that are sold on a retail basis to consumers must have their ingredients listed on the label. Without such an ingredient declaration, they are considered misbranded and are illegal in interstate commerce. FDA requires the ingredient declaration under the authority of the Fair Packaging and Labeling Act (FPLA).
How do I report an adverse reaction to a temporary tattoo or other cosmetic?
FDA encourages consumers to report any adverse reactions to cosmetics either to their nearest FDA district office or to FDA's Office of Cosmetics and Colors. Here's how:
To contact your nearest FDA district office, you can find their phone numbers on FDA's Web site. These phone numbers also are included in the U.S. Government listings in the Blue Pages of the phone book under United States Government/Health and Human Services.
To contact FDA.s Center for Food Safety and Applied Nutrition (CFSAN) Adverse Event Reporting System (CAERS), call (301) 36-2405 or email CAERS@cfsan.fda.gov .
Latest Update: Monday, May 22, 2006
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