When I first jumped on hair boards and the like, the unanimous consensus was that oils do NOT moisturize hair. Water is the ultimate moisturizer, therefore we should look for moisturizers that have water as the first ingredient, followed by ingredients that add moisture to the hair, like glycerin and panthenol (B5). Next, after the hair has been moisturized, oils seal moisture into the hair. This process is known as “moisturize and seal” and helps Black hair stay moisturized much better than using water alone. As a scientist, this makes perfect sense to me. Water (based products) followed by oil equals the most moisturized hair.
Recently, I see tons cute graphics and blog posts titled “best, most moisturizing oils.” All the while I’m thinking HUH? What happened here? Why are we going backwards in our hair care? Part of the purpose of hair blogs – especially those directed towards black hair – was so we could properly educate ourselves on the best practices for growing healthy, longer hair. If the information is wrong, then the practices to follow surely will also be incorrect and our hair will suffer. I believe everyone can grow beautiful, healthy hair with the correct knowledge and proper care. However, I realize I’m not THE authority on Black hair. So, after seeing so many posts about moisturizing oils, I had to ask myself do oils moisturize hair? Do I have it all wrong? So I decided to do a little research. According to Merriam Webster:
Moisturize (transitive verb): to add moisture to
Moisture (noun): a small amount of a liquid (such as water) that makes something wet or moist
Interesting definitions. And although water is the example used, oils certainly fit the definition of moisture as well. Oils are liquid and then can make something wet, right? How does this apply to hair care? Well, most oils don’t actually penetrate the hair shaft. They only coat the hair but don’t actually make the inside of the hair shaft wet, therefore they are NOT providing moisture.
In looking at the anatomy of hair in the image above the cuticle is the shingled, protective outermost layer of the hair, comprised mainly of keratin. Water easily penetrates the cuticle to reach the hair shaft to provide moisture. Oils, although also liquid, are slightly different. Oils are made up of various sized fatty acids. Some long, some medium, some short. Oils made up of long-chain fatty acids are too big to penetrate the hair shaft, therefore they do NOT have the ability to moisturize (or make wet) the hair. However, smaller fatty acids can penetrate the cuticle, which explains why some oils are thought of as moisturizing while others are used strictly for sealing moisture into the hair shaft.
Coconut oil is comprised primarily of medium chain fatty acids, which is why it is small enough to penetrate the hair shaft to provide nourishment directly to the hair shaft. Coconut oil has been proven to prevent moisture and protein loss, leading to less breakage when applied as a pre-poo treatment. However, two other oils – avocado and olive – that are said to be able to penetrate the hair shaft are both made of long-chain fatty acids so I would venture to say those sources are incorrect unless there is experimental evidence to the contrary, which I was unable to find. Furthermore, even though coconut oil can penetrate the hair shaft, it is solid at cold temperatures so I would not rely solely on coconut oil as a moisturizer. Some people only apply water during wash days, but a true moisturizer of some sort, even if it is plain water does touch their hair at some point.
Given the information above I conclude oils do NOT moisturize hair.
Use oils after applying your water based product to seal moisture into the hair.