What is Hygral Fatigue?

Formulate user Janie wrote in with some questions about hygral fatigue and porosity:

Hi there. I've heard hygral fatigue be referred to as 'over conditioned hair', 'over moisturized hair', and just as 'damaged hair'. What is hygral fatigue? Is it something that has to do just with using too many conditioning or moisturizing ingredients on your hair, to the extent that it damages your hair? I've also heard that it worsens the porosity of hair. This is confusing to me, as I was always under the impression that using products that condition the hair is helpful for porosity. I'm overall very confused. What is hygral fatigue, and does hygral fatigue worsen high porosity hair?

Thanks for writing, Janie!

Before we get into our response, we want to clarify something: while hygral fatigue is sometimes referred to as hair that's over-moisturized or over-conditioned, those descriptors don't really provide an accurate understanding of what hygral fatigue is. We're thinking that this probably added to the confusion for you! Hygral fatigue is better explained by thinking about it as hair that's undergone way too much exposure to water, rather than hair that's undergone too much exposure to conditioning agents. Keep that in mind as we dive into our explanation below.

What is hygral fatigue?

Hygral fatigue is the process by which a material becomes structurally compromised due to repeatedly swelling with water.

Many materials, particularly natural materials, become misshapen when exposed repeatedly to water. If you've ever put a wooden spoon or a cutting board in the dishwasher only to have it come out warped, that's hygral fatigue in action. The wood absorbed water, changed shape to absorb the water, and then maintained the new shape when it dried.

The same basic principle applies to hair, though it's less obvious to the naked eye - hair fibers are tiny, so it's pretty difficult to see the warping as it happens.

When a hair fiber is immersed in a liquid, it absorbs some of the liquid and expands. The outermost layer of the hair, the cuticle, is misshapen by this process. The teeny tiny scales that make up the cuticle are pushed out of their usual place, since they have to accommodate the extra bulk of the absorbed liquid. Once the hair fiber dries, these scales typically fall back into place, though frequently they don't - instead, they remain lifted, and stay pushed out of their normal formation.

Seeing as we live in a world that's full of water, hair fibers frequently are exposed to moisture. This cycle of swelling and drying is repeated hundreds, if not thousands of times during a hair's lifespan. And because this process happens over and over and over, the damage becomes worse and worse - those scales become pushed further out of place each time the hair goes into water. The structural integrity of the hair fiber is weakened until it essentially falls apart.

Does hygral fatigue increase hair porosity?

Yup! Hygral fatigue increases porosity.

If you're not familiar with the concept of hair porosity, it's the level to which hair fibers are able to absorb and retain moisture. The hair cuticle, that thing that we talked about before with all of the tiny scales, dictates how porous a hair fiber is.

If the cuticle is fully intact and there are no scales pushed out of place, the hair fiber has low porosity. This is a good thing - the hair cuticle is the hair fiber's suit of armor against things that could harm it. Low-porosity hair tends to be shiny, and is less likely to become tangled up with other hair fibers, so there's less of a problem with knots.

Hygral fatigue, by definition, means that the hair fiber has become swollen enough to push the scales of the hair cuticle out of place, leaving gaps. When there are gaps in the cuticle, moisture is able to enter the hair fiber more easily than when there are no gaps. And as you might expect, this causes the hair fiber to absorb even more water than it did before, worsening the hygral fatigue and further damaging the hair, resulting in increased porosity.

What should you do if you're dealing with hygral fatigue?

If you're already got high porosity hair and you're concerned by the potential impact hygral fatigue could have on your hair, there are a couple of steps you can take. First off, wash your hair a little less! If you can reduce the amount of time your hair spends immersed in water, you'll reduce the amount of damage caused by water.

It'll also help to start using a conditioner with some specific ingredients from the silicone family. Yup, you read that right, we said silicones! Though silicones get a bad rap in some circles due to a belief that they "weigh down" the hair, they're some of the most effective ingredients out there for sealing the hair cuticle.

Silicones are hydrophobic, so they repel water and are attracted to lipids, such as those in your hair fiber that have been exposed due to gaps in the hair cuticle. Silicones get nice and cozy within those gaps, and form a protective barrier between the exposed parts of your hair and the outside world (this is the same role that the missing cuticle scales used to play, before they went missing). While silicones aren't permanent, they're quite useful in the short term, and can be re-applied every time you condition your hair.

If you want hyper specifics, one type of silicone that's particularly useful for hygral fatigue and high porosity is Propoxytetramethyl piperidinyl dimethicone, from the dimethicone family of silicones. Beyond sealing the hair cuticle, it also helps to balance the amount of moisture in the hair fiber. This silicone can hydrate hair that's become dry and brittle, a common problem for hair fibers that have suffered from a breakdown of the hair cuticle. We'd highly recommend it, as we utilize it in many of the products that we formulate.