Understanding Porosity, The One Thing That Actually Decides What Works On Your Child's Curls
Twenty five years ago, nobody was talking to me about porosity. Not in cosmetology school, not in the salons I trained in, not in the magazines stacked in every waiting room. We talked about curl pattern. We talked about frizz like it was a personal failing of the hair rather than a moisture signal. It took me years in the chair, watching two clients with almost identical curl patterns walk out with completely different results from the same product, to understand that curl type was never the whole story.
The missing piece was porosity, how open or closed the outer layer of the hair strand is, and therefore how easily that hair takes in moisture and how well it holds onto it once it has. I did not learn this from a textbook. I learned it from paying close attention, year after year, to hair that was not behaving the way the chart said it should. Once I understood porosity, half the mysteries of my career stopped being mysteries.
This is REIGN's flagship lesson because it is the one thing I wish every parent knew on day one. Not curl type. Not the newest product on the shelf. Porosity.
What porosity actually is
Every strand of hair is covered in a layer of overlapping cells called the cuticle, the same way shingles overlap on a roof. Porosity describes how tightly or loosely those cuticle layers sit against the strand.
When the cuticle lies flat and tight, moisture has a harder time getting in, but once it does get in, it also has a harder time getting back out. That is low porosity hair.
When the cuticle sits more open, moisture moves in quickly, but it also escapes quickly, because there is nothing holding it in place. That is high porosity hair.
In between sits what most people would call normal or medium porosity, hair that absorbs and retains moisture at a fairly balanced rate, without much extra help required.
None of these are better or worse than another. They are simply different, and each one asks for a slightly different kind of care.
The signs, without a lab
You do not need a laboratory to get a useful read on your child's porosity. You need to pay attention the way I learned to, through pattern and repetition, not a single test.
Low porosity hair often takes a long time to get fully wet in the shower, water tends to bead on it at first rather than soak in right away. It also takes longer to dry once wet. Product tends to sit on top of the strand rather than absorb, which can leave hair looking coated or weighed down even with a small amount applied. This hair can be more prone to build up.
High porosity hair usually soaks up water almost instantly, and dries surprisingly fast for how much moisture went in. It often feels dry again within hours of a wash, even after a heavy application of product, because the moisture that went in did not stay. It can also tangle more easily and feel rougher to the touch.
Normal porosity hair tends to fall in the middle of all of the above, it absorbs product at a reasonable rate, holds moisture reasonably well, and generally responds the way most product instructions assume hair will respond.
There is a home test some parents have heard of, dropping a clean strand of hair into a glass of water and watching whether it floats or sinks. I will be honest with you about that test the way I would be honest with a client in my chair. It can offer a rough clue, hair that sinks quickly may lean higher porosity, hair that floats for a long time may lean lower porosity, but it is far from precise. Product residue, water temperature, and the specific strand you pull can all skew it. I trust the daily signs above far more than I trust a glass of water, and I would rather you trust your own observation of your child's hair over several wash days than a single test on a single strand.
Why this matters more than curl type ever will
Here is the moment that changed how I practice. I once worked with two clients back to back, similar curl pattern, similar density, similar hair color even. I used the same rich, deeply moisturizing product on both of them because the curl chart said that pattern called for it. One client's curls looked luminous and defined for days. The other's looked flat, greasy, and weighed.
The difference was not the curl pattern. It was porosity. The first client had hair that could absorb and hold that richness. The second client's hair, higher porosity, could not hold onto that much product, it just sat on top, heavy and unabsorbed.
That is the lesson I want every parent reading this to walk away with. Curl type tells you the shape. Porosity tells you what that shape can actually use. When a product disappoints you, before you assume the product failed, or worse, before you assume something is wrong with your child's hair, ask whether the product ever matched the porosity it was going onto in the first place.
Caring for low porosity hair
Low porosity hair generally does best with lighter products applied to damp, not soaking wet, hair, since a lot of extra water on top of already slow absorbing hair can just add to the buildup problem. Warmth helps this hair type absorb product, a warm shower rinse or even sitting under a warm towel for a few minutes before styling can open the cuticle just enough to let product in more easily.
Clarifying gently and regularly matters more here than for other porosity levels, since product tends to sit on the surface rather than absorb. A sulfate free shampoo like our Shampoo Dreams, used consistently, helps prevent the buildup that low porosity hair is especially prone to holding onto. Also if you feel like the hair doesn't feel clean after a shampoo, you can do a second shampoo to make sure you are getting all the excess product out.
Caring for high porosity hair
High porosity hair generally needs richer, more emollient products and often benefits from a layering approach, a lightweight leave in followed by something to seal that moisture in before it has a chance to escape. This is where our Magical Leave-In Cream earns its name as a hero product, since it is designed to moisturize and define in one step, and for thicker or Type 4 textures that run high porosity, pairing it with an additional leave in and a sealing oil gives that moisture something to hold onto for longer.
Gentle handling matters too, since high porosity hair often feels more fragile and prone to tangling. Detangling with care, and conditioning consistently with something like our Conditioning Clouds, helps rebuild some of what that open cuticle tends to let go of.
Caring for normal porosity hair
Normal porosity hair generally has the most flexibility, most standard curl products will perform close to how they are described on the label. That does not mean this hair needs no attention, it simply means you have a bit more room to experiment and find what your particular child's curls respond to best, without porosity working against you at every turn.
The mistake almost every parent makes, without knowing it
I want to say this gently, because I have watched it happen again and again and it is never anyone's fault. Nobody taught most of us about porosity. So when a product does not work, the instinct is to assume we bought the wrong thing, or that our child's hair is simply difficult, or that we are somehow bad at this.
None of that is true. The truth is far kinder. You were simply missing one piece of information that almost nobody hands parents on day one. Porosity is not a flaw to manage in your child's hair. It is not something to fix. It is a fact about how that hair works, the same way eye color or shoe size is a fact. Once you know it, you stop struggling with your child's hair and start working with it.
That shift, from a struggle to working with, is the whole point of REIGN. Your child's curls were never a problem to solve. They were always a crown. Understanding porosity just means you finally have the right tools to care for that crown the way it actually needs, rather than the way a chart assumed it would.
What to read next
Find Your Curl Type, if you have not already, pair this with the shape of your child's curl pattern for the fullest picture.
A Wash Day Routine That Actually Works For Your Child's Curls, where porosity and curl type come together into an actual, practical routine you can use this week.