Ayesha asks: I just wanted to ask, when we talk about oils and other natural stuff coating our hair, does it mean it forms a layer on the hair, preventing the penetration of water to the hair shaft when you have a shower and wash your hair?
Not necessarily. Oils do form a coating around your hair strand which slows down evaporation of moisture off of your hair, but it will not prevent moisture from getting in.
If you oil dry hair and then mist it with water it will still absorb it and puff up. So in this respect it will not stop moisture from getting in, but your hair will not absorb as much water as quickly with oil on, as it would if your hair had no product on. So it will take more water to reach maximum saturation.
This of course depends on the type of product you are using. Natural oils create what i consider to be breathable layers, which means that they will not clog the hair’s cuticles or the scalp’s pores. Other products however, may very well hinder moisture absorption such as mineral oil and silicones. Silicones may not suffocate the hair as much as mineral oil but if over used it can create an impermeable barrier which will leave your hair dry, dull and lifeless.
Washing your hair with oil already applied still allows the moisture to get in, keeps the hair soft and prevents it from being overly dry afterwards. That is why so many people use oils as a pre wash treatment to soften and ‘protect’ the strands during the shampooing session.
Using a gentle shampoo will not strip all the oils off your hair and thus allows it to still be soft and moisturised. Using a harsher shampoo containing sulphates or coco betaine will remove or strip off most, if not all of the oils on the hair.
Co-washes will not remove all product build up such as silicones and heavy butters but still offers a mild cleansing experience.
So… in summery
Oils don’t stop moisture from getting in. Other products such as mineral oil and silicones may prevent moisture from entering if allowed to build-up and washing your hair with oils already on your hair will not stop the water from penetrating the shaft. Oils used as pre wash treatments can help protect hair from drying out whilst washing. Using sulphate and coco betaine shampoos will remove all product build-up whilst co-washing and gentler shampoos will not strip all the natural oils off the hair, maintaining softness.
Check out The Natural Havens post on Oils to gain a better understanding of how they function on hair.