"Terps" is a handy word artists on Henna Page  use to refer to terpenes, especially monoterpene alcohols.  Plants make terpenes, just like they make starches, proteins and sugars.  Some plants have high levels of monoterpene alcohol, and we can use these by distilling their essential oils.  See "Essential Oils, A Users Guide" by Alex Morgan, Catherine Cartwright Jones and Marianne Marsland, for an explanation of this, and a discussion of which ones are safest and most useful!

What are "Terps" and why put them in henna?

Many essential oils  contain  terpenes which are hydrocarbon solvents. Hennotannic acid, the dye in henna,  is hydrophobic rather than hydrophilic, thus water is not the most effective means to release and darken henna.  One of the most useful and least harmful of these terpenes is terpineol, found in  high concentrations in Tea Tree, Cajeput and Ravensara essential oils.  In every test we did, the addition of these essential oils made a paste that stained quickly, and darkened rapidly.   Pure terpineol makes dark henna stains comparable to these essential oils.  Essential oils lacking terpineol and similar terpenes do NOT improve stain. 

Other hydrocarbon solvents have  been used to create quick dark stains, but some of these are very toxic.  Gasoline, kerosene, and turpentine darken henna stains but are very dangerous to use! 

Terpenes with low toxicity, but which  facilitate henna stains are terpineol, geraniol, cineol, cedrol, linalool.  Eugenol facilitates dark henna stains but can irritate skin.  Camphene facilitates dark henna stains but can cause intoxication or nausea.   Less helpful are eucalyptol, and citronellol.

Essential oils that have reliably high levels of the safest, most useful monoterpene alcohols are: Tea Tree, Cajeput, and  Ravensara. 

Tea tree essential oil is the most reliable "terp" because the Australian government regulates the level of terpineol in it. Aromatherapy grade Cajeput and Ravensara do just as good a job, and smell better. Some Tea Tree essential oils can have a hellacious funk.

Essential oils that are nearly as good are: Lavender,  Geranium, Cardamom, Cypress, and Cypress Tips. 

Essential oils that have lower levels of effective terpines, but which still darken henna somewhat are: Neroli, Pine, Juniper, Thyme,  Rosemary and Marjoram.

Helpful oils that can cause skin irritation which should be used sparingly are Clove Bud oil, and Black Pepper oil.  Citrus oils are phototoxic, therefore are not suitable for outdoor festival use. Camphor is an excellent darkener, but it is a transdermal intoxicant and can make the hennaed person ill.  Cinnamon oil and Clove oil can cause dermatitis, so should be avoided. 

Use aromatherapy grade essential oils!  These are safest and most effective!

Should you use "Mehndi Oil"?

Some "Mehndi Oil" products are useful "terps" but many of them are unregulated, and have unlisted ingredients that may give you a rash or make you sick. These can include camphor, kerosene, lamp oil,  or other adulterants.  Don't put something on your skin that doesn't have an ingredient list! 

Should you use "Eucalyptus Oil"?

There are 700 varieties of Eucalyptus tree, and many different ways of distilling Eucalyptus oil.  A few of these products darken henna safely and effectively, but most DO NOT and are a waste of money. Some products marked Eucalyptus oil have unlisted ingredients and are downright dangerous.  If you want to use Eucalyptus oil, buy a little and try it first before buying a lot. Aromatherapy grade Eucalyptus Globulus is your best bet.

What is NOT happening with "Terps"?

These oils are not "warming" the skin or increasing circulation.  Ginger essential oil, specifically used to warm skin and increase circulation has little or no effect on the stain results .... ginger has none of the  useful terpenes.  It is not the "oil" that is creating this effect.  Plain oil, such as olive oil, has no effect on the stain. Essential oils distilled from resinous plants which have none of the useful terpenes have little or no darkening effect  ... myrrh is one such.  These oils are not opening pores, or doing anything mystical.  These are simply solvents working in the henna paste to very effectively make the henna dye available, and facilitate a very fast oxidation  (darkening of the henna stain). 

Rubbing terps into the skin before and after applying henna produces no stain improvement. 

The monoterpene alcohol has to be mixed into the paste a few hours before application.  Pastes applied immediately after the "terps" were added did not stain as well as those left for an hour.  The best stains came from paste that had "terps" mixed in from 4 to 48 before applying when left at 80F. 

So, to summarize "What are "Terps" doing and Why should you use them?"

Henna is hydrophobic, not hydrophilic.  That means that henna dye will become more available in a monoterpene alcohol than in water or lemon juice.  If you "terp" your henna, you will get more dye out of the henna and into your skin.  Your skin will have more dye in it, and therefore be a more intense color.  "Terps" make far darker stains on torsos, arms and legs.  If you use "terped" henna on a hot day, you may get dark stain quickly, in 2 hours, and you won't need to wrap or seal.

Because different essential oils have different levels of monoterpene alcohols, there is no good answer to "how much "terp" do you add?"  Many henna artists find that 4 drops of terps per gram of henna powder does the job ... but every artist has to figure the amount, and what sort of terps to use! For specific "Terp" mixes, see the Catherine Cartwright-Jones's "Serious Henna Mixes"

You know not to waste your time and money on premixed cones. You've bought a box of Henna from your local store merchant or on-line. But your Henna is a little drab, nothing like those amazing results you've seen on-line or on people. You want something with a little more kick. Something more noticeable? Yeah, something people really take note of. All right, terps are for you. 

What is a terp? Terp is a slang term, used by henna artists to refer to the terpenes in an essential oil that help to boost henna's staining ability. What are these essential oils? The 'what' of essential oils boils down to combinations of the defined terms. There are some oils, like rose, that have so many constituents that not all of them are known or even categorised. To know what, exactly, a given essential oil is, you need to be asking something more specific. It's like asking what a drink is- water, orange juice, tea and gin are all drinks, but all very, very different! It kind of depends on what you are looking for then! A better question might be something like, "What is Tea Tree essential oil?" That can be fairly easily answered: The main chemical components of Tea Tree oil are: Terpinene-4-ol, Cymene, Pinene, Terpinene, Cineole etc. In other words, it is a combination of a few different types of terpenes. The best essential oils for henna come from a series of trial and error studies. It appears that mono-terpenes of the alcohol and possibly oxide variety work together to provide the best action on henna. That said, the oils one decides to use for this effect all have various dependencies for making the best effort. Time, age, and origin play a huge role in this.

As we all know, the best way to get a nice dark henna stain is with fresh, pure henna and a reasonable amount of lime or lemon juice (i.e. something acidic to release the dye in the henna.) We've played with the chemistry sets long enough to have determined that you can also add a 'helper' of a small amount of an essential oil. It seems, at this point, that alcohol (not the drinking kind, either!) terpenes of the terpineol and cineol (and related ~eol's) nature are the best. The fun part about this relates to the kitchen witch theme. Everyone can have their own special secret blend. These can be added to impart a lovely fragrance to your henna mix and they will help quickly push the stain to something really dramatic. Everyone adds something a little different.

The oils that appear to have the most effect are Tea Tree and Franincense. Oils like Rosemary, Geranium and Lavender have lesser effect, but also help make the fragrance really enjoyable. The thing to remember is that these oils are chemicals. Just because they are natural does not mean they will be safe for everyone in general. It is still a good idea to grill people on their allergies and sensitivites and raise awareness to what is in your mix in general. Essential oils are POTENT substances and most of them should never be used undiluted on bare skin. Very few essential oils meet the sensitivity requirements that allow them to be applied 'neat', that is, undiluted. Some of those are Rose, Sandalwood, Lavender and Tea Tree. Therefore, use amounts that follow general dilution rules in your henna mix to maintain safety and always question clients (and friends and family too!) on their allergies.

Something important to know about oils is how and where to store them. Your essential oils should come from quality suppliers that properly label and store their oils. They should also be able and willing to provide you with MSDS (Material Safety and Data Sheets)when requested. When you find a new supplier, whether online or in person, find out what they know in addition to finding out prices. Are there oils stored properly? Are they labeled properly? Do they list the United States as origin? All of these can be red flags. The oils you purchase should be labeled as 100% pure essential oil. Anything else is suspicious. Even '100% essential blend' sounds like a knock-off and probably is. Smell it. Essential oils are strong, potent and fascinatingly real smelling. If you are smelling something that smells like soap or shampoo- there is a reason the price is so low. Oils should be stored in dark glass bottles. PERIOD. If it is in plastic, leave it alone, please. If it is a clear bottle, leave it alone. Do not buy oils that are in the front of the store in direct sunlight. Heat and light break down chemical components. Store your purchased oils in a cool, dark place. You can refrigerate them, but do not freeze them! Most oils last if properly stored, but research your oils and be aware of the time frame for use. They do not necessarily age gracefully. Citrus oils in fact, should be used within 6 months of purchases. Bear in mind with all of this that you do not necessarily know how long that oil has been stored before you even bought it. The supplier I buy from lists the year and season of the crop. That's why I buy from him. Trustworthy with dated facts, not hyperbole about the wonder of nature. We're henna artists, we know about that already!

Alissa: I prefer cajeput oil for a terp, but will often add other scents that have terpine-like qualities to the mix as well. At a minimum, I add one dropperful (approximately 20 ml) per dry spoonful of henna mixed.

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