The use of plant oils has been common practise for centuries. Carrier oils not only add shine but can offer many lubricating properties to the hair.
Healthy hair is naturally hydrophobic, meaning, it loves water – but we don't necessarily want too much water entering the hair too quickly, as it can swell (and look all "poofy"), then shrink again when it's dry, and repeat all over again when you shower next, causing hygral fatigue and breakage. We do need water in the hair, but the challenge is to find the perfect balance for your specific hair type.
Different oils naturally offer different benefits to the hair. Although most oils will help repel water by sitting on top like a film, some oils are able to penetrate more than others and offer added benefits to the hair – especially if you have dry, coarse, sun-damaged or styling-damaged hair. This doesn't mean you're going to run out and dunk a whole container of oil on your head (gosh, don't do it!) because you'll end up with a greasy head that'll be tough to wash off. It may also not be the best oil for your specific hair type, plus there are proper ways of applying oil to your hair, depending on the type of hair you have and the oil you choose for it.
Oil use on hair is not a one-size-fits-all solution, by any means. I've tried the most renowned penetrating oil (coconut) on my hair and it just felt terrible after: It was super greasy, crunchy, and couldn't easily wash it out – even though I used it pre-poo, which means before washing, which is how it's best recommended. I had to use loads of shampoo to wash it out and I ended up completely drying out my hair from so many repeated washes, having to start from scratch (so frustrating!).
My best advice: Experiment with a couple of different ones and see what your hair prefers.
A note about hair porosity
If you search for "hair porosity" on Dr. Google you'll find loads of DIY tutorials and guides on how to figure out whether your hair is low or high porosity. This method basically suggests that you pull out one single hair strand and carefully place it inside a cup of water to see whether it sinks (high porosity) or floats on top (low porosity). I mean, really??
I personally don't think an adult can typically have one single type of hair porosity and have discussed this on many occasions on our live "Haircare Formulators Club" on Clubhouse. Unless you have a baby's brand-new beautifully virgin hair, your hair has likely been damaged in some form or another – whether by the drying effects of the sun, overuse of styling tools, chlorine water, colouring, hormonal changes, etc etc.
Hair is typically lower porosity closest to the scalp, where it can feel smoother as cuticles are tightly wound together, and won't need as much moisturizing because it has easier access to the scalp's production of sebum, the natural oils produced by the sebaceous glands (which are both moisturizing, protecting, anti-inflammatory and anti-fungal!). As it grows along, it's more likely to turn into higher porosity, as the sebum has a tougher time reaching aaaaall the way down to it. The longer the hair, the more you can benefit from adding some beautiful oils to your hair.
A little chemistry chit-chat that you WILL understand!
It would be difficult to talk about oils and hair penetration without touching on the chemistry bit, and understanding how it works and why it matters. The most important thing you must figure out is the triglyceride composition of an oil, to determine whether it will penetrate or seal the hair.
"Triglycerides are esters in all oils, and they're made up of glycerol and 3 fatty acids – either saturated, monounsaturated, or polyunsaturated triglycerides."
Fatty acids (whether saturated, monounsaturated and polyunsaturated triglycerides) are the building blocks of all oils. Fatty acids are made up of long chains of varying numbers of carbon atoms with hydrogen atoms attached to it (I know what you're saying, "bla bla bla chemistry hate it bla bla - but it matters!). These chains and patterns are what make up the different qualities in the many different types of oils you can choose to work with:
Short-chain fatty acids – Will penetrate the hair strand.
Medium-chain fatty acids – "May" (or not) penetrate the hair strand.
Long-chain fatty acids – Will not penetrate the hair strand, or barely, and will instead sit on top, or coat the hair.
As you can see, it's not as easy as saying "ooh, I like this oil because it smells nice. Let's use it in the hair!" Lipids (or oils) are much more complicated for one blog post, and of course we would have to consider unsaturated fatty acids, super or polyunsaturated fatty acids, and a whole list of carbon chains and hey, I'm not a scientist here so let's get down to hair business:
Why would we want an oil to penetrate the hair strand?
Oils with short carbon chains have been shown to penetrate better than those with longer carbon chains, bonding with proteins inside the cortex. This means that the benefits of that particular oil – the vitamins/nutrients/benefits it contains – can have an effect on the health of your hair! Exciting, isn't it? Now imagine what happens when that particular oil has been infused with beautiful herbs? Ooh-la-la!
Oils that are made up of saturated or monounsaturated fatty acids are best for penetrating the hair strand. These penetrating oils are best for dry, porous, rough-feeling, coarse hair; if you want your hair to retain moisture, or improve its elasticity, these oils can make the hair more hydrophobic (another sciency word for "water-repelling") because they would penetrate and then in turn repel water from going inside the hair strand to soak in with it. Imagine rubbing oil on your hand and then pouring water on top. These oils can cover hair gaps that friction and damage has caused over time, rather than water covering those gaps. Get it? ;)
Why choose a sealing oil for your hair?
Some hair type responds better to oil that doesn't necessarily penetrate as much, but it seals the hair strand: If you want to reduce friction between hairs, as they rub together from dryness and if you want to retain moisture as it seals the hair from preventing water penetration. And most importantly, sealing oils can improve slip, combing, and make hair glossy and shiny. If your hair is thin or fine, sealing oils are more likely what you need.
"Remember, almost any oil will repel water, but it can either sit on your hair filming over it or by soaking in and penetrating the hair shaft."
So the oil you choose, matters. Don't just grab your kitchen's cooking oil and go crazy, nooo no gosh no...
PENETRATING CARRIER OILS
Typically, these will be oils with saturated or monounsaturated fatty acid compositions, with a compact molecular structure and slight positive charge. These oils also work best when they're slightly heated (even warmed up slightly between the palms of your hands as you rub them quickly together), and used pre-poo (before washing your hair) to prevent too much water penetrating the hair strand. These types of penetrating oils include:
Raspberry seed oil
Squalane olive oil
SEALING CARRIER OILS
These oils are typically high in polyunsaturated fatty acid compositions, with a short (less than 18 carbon chains) molecular structure.
Castor oil or Jamaican castor oil
Rice bran oil
Broccoli seed oil
Can you choose a combination of the two?
Sure you can! Again, it really depends on your hair type and what you're looking for in a carrier oil and its benefits to your particular hair.
What about butters? Are they good for hair use?
Butters work pretty much the same as liquid oils, they just have a higher amount of saturated fatty acids, like stearic acid, which contributes to how solid the butter is. The difference is that butters will typically not moisturize the hair because they don't contain water. In order to penetrate the hair strand, a fatty acid has to have a pretty small molecular chain in order to penetrate.
Some butters may penetrate slightly because of their low content of lauric acid, but they will protect the hair, soften it, add shine and manageability. For low-porosity areas of the hair and for thinner hair types, TRUU by Nature recommends using light oils like jojoba, argan or grapeseed oils, while for high porosity areas of the hair and for thicker hair you could use some mango, cupuacu or shea butter – which we all love so much! These butters are best used on dry hair so they work well to seal the hair strand rather than on wet hair which can make it draggier and more difficult to comb.
Which oils are you most curious to try? Which ones have you tried already? Are there any missing on our list that you think we should add? Comment below and let us know.