Have you noticed that some hair products are easily taken in by your hair, and others just sit without fully penetrating it?
There is a perfectly good explanation for this, and that is the difference between absorption and adsorption.
Similar terms, but opposite meanings
The term absorption is used all the time when we talk about skin or hair care. In fact, there is a tendency to believe that because a product gets absorbed by the hair -or the skin- that we are properly taking care of it. On the other hand, the term adsorption is seen as something negative. We tend to believe that if a product sits and does not get fully absorbed, then we’re not receiving its full potential.
Absorption and Adsorption in detail
Absorption happens when a substance or ingredient is capable of reaching beyond the outer layers of the skin (epidermis and dermis).
In terms of hair, absorption refers to the ability to reach beyond the outer layer, the cuticle. More specifically, in hair, most molecules get absorbed intracellularly, through the spacing between the micrometric scales that form the cuticle. One of the main variables for absorption is the level of porosity of the hair: the higher the porosity, the higher the possibility for a substance to be absorbed.
Adsorption is the ability of a substance to sit in the outer layer of the skin or outside the cuticle for the hair. We observe this with conditioners or heat protectors, some of their ingredients will remain unabsorbed, but rather adsorbed, creating a protective layer for the hair strands.
Which one is better?
It depends on the final purpose. When you want to protect the strands, look for ingredients that will get adsorbed on the hair like grapeseed oil.
For nutrition, ingredients such as argan and avocado oil will get absorbed deep inside the cuticle providing vitamins and nutrients for a healthier hair structure.
Actives that get absorbed and adsorbed are both equally fundamental for a complete Hair Routine.