Yes, moisture is the solution for dry hair because dry hair comes from losing too much moisture. But it's not as simple as running water through your hair as that will just waterlog your hair and cause further damage, possibly even making your hair drier. This is because water swells and stretches your hair when it gets wet, then your hair contracts as it dries, and that can be damaging. And although the the water does “moisturize” your hair for a brief period of time, you cannot keep it wet 24/7.
This repeated process of swelling and contracting will damage your hair, cause split ends and even complete breakage. This is why water is not a solution for dry hair, and can be worse for you overall. Truly moisturized hair comes from maintaining a balance of water and lipids. Moisturized hair will feel soft to the touch (but not greasy), and bend without getting any crinks in the strands.
Each hair strand consists of three main parts: the inner medulla, the middle cortex, and the protective outer cuticle layer. And each is important for allowing the molecules, nutrients, and chemicals that help moisturize your hair to become absorbed and stay in the right place. The outer layer needs to allow the molecules to pass through, and then close to keep them in the strand for example. And the right moisture components need to be used. Let’s go back to water as our example.
Because your hair is porous, it absorbs water molecules when submersed (like in the shower or in the pool) but those same molecules will later evaporate. How much, and how quickly they evaporate depends on the air and other elements (lipids) on your hair, such as your body's natural lubricant called sebum, along with other conditioning agents from hair products you use. That’s where modern science, water, and other ingredients can work better when combined.
Sebum and conditioner agents (like silicones or cationic surfactants) help maintain your hair's moisture by sealing the outer cuticle layer. This helps both to keep excess water from evaporating from your hair, and to prevent your hair from absorbing excess water, especially from the humidity in the air. As an added bonus, these agents help keep your cuticles laying flat which makes your hair look shinier and also helps prevent frizz.
But sebum and conditioning agents get washed out when you shampoo, which might dry out your hair. And because sebum comes from glands inside your scalp, your body might not even produce enough to reach the ends of your hair, especially if you keep it long. The type of shampoo you use also makes a difference in how much they get washed out, which makes a difference for how much moisture your hair is able to retain.
For example, clarifying shampoo tends to be high in specific sulfates that are healthy for your hair and do a great job of clearing out any buildup, but in the process they remove much of your natural sebum. This is why washing too frequently, or using a shampoo that is wrong for your hair can lead to dry hair.
Fortunately, washing your hair with the right frequency and using a conditioner will help maintain your hair's proper moisture balance. If you still find your hair is too dry, like if you notice lots of split ends or excess shedding (lots of broken hairs that come out with hair ties or hats), hair oils can work magic. But not all oils are created equal, so make sure to use high-quality products with coconut or argan oil, both of which have low molecular weights that allow them to penetrate inside the hair cortex layer, and help maintain proper moisture balance from the inside out.
Moisture is the way to help make dry hair feel and look better, but water alone doesn’t solve the problem. It is a combination of getting the right moisture compounds into and on the hair shaft, and keeping them there as long as possible. If you found this guide to dry hair and moisture helpful, subscribe to our blog below for more hair health and styling tips.