When shopping for a new conditioner, we are confronted with a myriad of promises and claims: But how should we know whether to go for the “rebuilding” product, the “repairing” or the “rehydrating” one? As always, I am a big advocate of taking one step back and reconsidering the matter in a more fundamental way: Before deciding what product to use in order to “fix” our hair, we should bring back to mind what exactly it is that we want to fix. Only if we know what we are mending and what is broken, we can chose a targeted and appropriate cure!
So let’s start with noticing that each hair shaft (as opposed to the hair follicle) consists of two or three different layers, depending on your hair type: An inside layer called medulla is surrounded by a middle layer called cortex and an outside layer called cuticle. The longitudinal section on the left and the cross section on the right side are obviously highly simplified, but I think they give you an idea of what we are talking about:
You can see the outside layer, i.e. the cuticle on the picture below (caucasian hair on the left and asian hair on the right side): As you can discern upon closer examination, the cuticle is made up of individual overlapping scales, which is why it is often compared to a tiled roof. Natural lipids secreted from the sebaceous glands in our skin seal the cuticle, making the scales lie flat and point down towards the ends. Just like fish scales or roof tiles, hair scales have got a protective function: They cover the second layer of our hair called the cortex.
(Creative Commons B0007307 Comparative thickness of human hair by Wellcome Images is licensed under CC BY-NC-ND 2.0)
The cortex is for most the most part made up of rod-like bundles of keratin fibers, which you can distinguish pretty well in this picture of a split, i.e. severely damaged hair.
The cortex also contains water, lipids and melanin, which is responsible for our individual hair colour. If the cuticle is in good condition, i.e. if the scales lie flat, the cortex is sealed and shielded from the outside: water and lipids are kept inside, and the hair is pliant, shiny and looks its best.
The third and inner layer of our hair is called the medulla, an open area at the center of each hair that can be completely absent in some hair types like blonde hair. It is irrelevant in terms of hair care.
From these pieces of information, we can derive the ideal state our hair should be in to look its best:
- The scales should lie flat, the cuticle thus being closed and sealed, keeping moisture and lipids inside the cortex.
- Vice versa, we must avoid opening or even tearing up the cuticle and exposing the cortex: The roughened surface of the cuticle makes the hair look dull and brittle, moisture and lipids can escape from the cortex, the hair loses its shine and elasticity and becomes prone to breakage.
If you want to know how to avoid such damage and how to achieve healthy looking hair, keep your eyes peeled for my next blog posts. Always remember though that the hair shaft we have just described is dead tissue! We can therefore not “bring our hair back to health”, as conditioners often tend to claim! Dead hair brought back to life and health…I guess, that would leave us with some kind of zombie hair? Not sure if that is desirable 🙂