Hair conditioners are slowly becoming part of everyone’s hair care routine, be it a rinse-off, leave-in or a deep conditioning treatment. We know that a conditioner makes our hair much more manageable by providing moisture that helps to remove frizz and dryness. It also provides the hair slip and conditioning that helps to de-tangle the hair and create a kind of film that enhances the smoothness and shine of hair strand. Some conditioners contain protein that add strength to hair. But have you ever wondered what could be the science behind it and how does a conditioner work? May be it will help you to choose the right conditioner for you next time.
Hair consists of three layers cuticle layer, cortex and medulla. The outermost layer is the cuticle layer that determines the look, feel and health of your hair. Cuticles are shingle-like layer of cells that protects the inner part (cortex and medulla) of the hair shaft from all forms of external damage. The more the cuticles lies flatter on the hair shaft, the healthier your hair will be, as flatter and closed cuticles do better job retaining the moisture inside. Natural shine of hair comes from the light reflected from the surface the cuticle layer. So, if cuticles lies flatter, more your hair shines. But sometime this cuticle layer gets damaged from our daily hair grooming activities like combing, washing, chemical treatments and damage done by environmental factors like sun, wind (more on what are causes of hair damage). Once this cuticle layer starts to worn out then hair begins to look frizzy and dry and this is the time you turn to a conditioner.
What does a conditioner contain
These are the main conditioning ingredients that a conditioner has and do most of the work. Our hair have negative charge. More the hair is damaged, the more negative charge it carries. Cationic surfactant are surfactants that are positively charged which bind to the negatively charged hair fiber and create a bond. These forms a film on the cuticle layer by coating it and provide the slip and reduce friction between hair fibers and hence easy to comb. Some of the common cationic surfactants are behentrimonium chloride, stearamidopropyl dimethylamine, cetrimonium chloride and behentrimonium methosulfate etc
These substances have water binding properties. These are added to the conditioner to provide the moisture to hair by binding the water inside. More on humectants in this post.
These are added to form a film on the hair shaft which makes it smooth, shiny and seal in the moisture inside. Common emollients are natural oils and butters like coconut, jojoba, shea butter etc, silicones, fatty alcohols like cetyl alchol, cetearyl alcohol etc. Apart from forming a film, some emollients do penetrate the hair to provide moisture and nourishment. Silicones are synthetic emollients that just sit on the hair surface and prevent moisture escape and do not let the moisture penetrate the hair from environment. This is where their anti-frizz property comes from. But with time these silicones tend to build up on hair so should be avoided in your products.
Proteins repair the damage and provide strength to hair. Depending on the molecular weight, some protein penetrates the hair and has the capability to improve the health of hair. Some of them have film forming capabilities and few of them also act as humectant.
Thermal protection and sun damage
Sometimes few conditioners have ingredients that provide protection from thermal damage while doing flat iron, blow dry etc and protect the hair from UV rays.
Like citric acid etc, these adjust the pH of the conditioner. Hair pH is around 4.5 – 5.5. Cuticles tend to open in alkaline solution and lies flat in acidic one. So, conditioners are made a bit acidic so that cuticles can lie flat after using it on hair. You can read more on how pH value works on hair here.