Learn what hair porosity means and how it affects you

Reading time 5 mins

High, low or medium porosity hair

Find out how to check whether you hair is low, medium or high porosity with a simple test. Learning which type it is will make a big difference in what you should or shouldn’t use in your hair care routine.

How much do bad hair days affect you?

My hair means everything to me.  I don’t care what my skin or body shape is doing, if my hair looks good, I feel good.  And I know many people who feel the same way, including my sons and my brother.  That may seem like a habit passed down from one generation to the next, it isn’t. My mum has never cared about her hair. My dad started going bald in his 20’s so hair isn’t his thing either. 

For me, the big problem with relying on my hair to feel good is that I have hideously difficult hair.  It can be curly, frizzy, flat, crunchy, stiff and floppy.  Hairdressers can’t style it (or cut it for that matter) and even they have to use hair straighteners to get it looking good.  GHDs are the only way I can style it too, although it takes 24 hours before it starts looking natural rather than stiff.  This much-relied upon styling method has been made all the more difficult by the last (overpriced) hairdresser who insisted on adding layers for “movement and volume” despite me saying there was already too much of both.  He realised this when trying to style his overly layered mistake and admitted it wasn’t doing what he expected (you don’t say…).  The blow dry lasted approximately 40 mins before it was a half floppy/half frizzy mess.

My apologies if you are a hairdresser, I don’t wish to be negative about your profession. It’s just I’m still seething over this last haircut, which I’ve now been growing out for five months, which was preceded by another haircut which took over six months to grow out…

Test your hair porosity type

Anyway I’ve learnt a few things along the way to make the best of what is a frustrating situation.  The first step for understanding hair and what it does or does not need, is discovering how porous it is.  If you know about this, then great, if you don’t, do this straightforward test.  Take a clean, product-free hair strand and drop it into a bowl, sink or glass filled with water.  It sinks – you have porous hair.  If it floats – you’ve got non-porous hair.  If it floats then slowly sinks, it’s medium porous hair.

So what exactly is hair porosity?

In a nutshell it’s the hair’s ability to absorb and retain water, of which there are three main types.  Your hair porosity is how open or closed the hair cuticles are. This determines its ability to absorb and retain water.  The hair cuticle is the outer layer of the hair shaft and looks like little scales when magnified. How open or closed they are controls how much product either penetrates or just sits on the hair shaft.  Your type is influenced by genetics and hair damage plus environmental elements such as sun exposure and pollution. Note your porosity type can change if your hair becomes damaged.  Knowing my hair porosity has been an important step in understanding which products do and don’t work for me. 

What are the three types of hair porosity?

It’s a simple grading system of low, medium and high.  Low porosity (LP) has flat, closely bound together cuticles which doesn’t allow moisture into the shaft, instead products just sit on it.  This type of hair tends to float in water.  High porosity (HP) has raised cuticles spread widely apart which easily absorb moisture and it will immediately sink in water.  Medium (MP), as you guessed it, is in-between and will at first float before slowly sinking.  

Standard beliefs about hair porosity

It is almost universally accepted that LP is straight uncoloured hair with little to no damage.  At the other end HP is hair that has been coloured / bleached, heat damaged or curly / coily.  I have to disagree with these standards. My hair is LP (float test and behaviour) and yet it’s curly with some heat damage and colour.  This is why hairdressers are constantly caught out by my hair behaviour.  

Low porosity behaviours

Hair maintains its self-produced moisture easily but it’s hard to make moisturising products penetrate through the cuticles. This results in the product just sitting on the hair shaft so you get build up.  The hair takes a long time for water to fully saturate it, a vital step before using shampoo. It also takes a long time to dry. The hair is prone to being weighed down and can have a lack of volume.  This is the type of hair that looks worse with conditioning shampoos, leave-in conditioners, heavy hair masks and any sort of oil.  It responds well to regular clarifying shampoos and lighter conditioning products .  LP hair also doesn’t take hair dye easily.          

High porosity behaviours

This type of hair seems to suck up moisturising products but loses them easily.  The hair becomes wet quickly and also dries fast. Colour takes easily and it can be stained by semi-permanent colours.  Hair can be frizzy and tangles easily.  Bonding treatments work particularly well as does using oils sealed in with creams. Heavy moisturisers are a must rather than lightweight ones.  Try to avoid overuse of a hair dryer and heat styling products. 

Medium porosity behaviours

Moisture enters the hair shaft easily as the cuticles are part open, but the moisture isn’t lost too quickly.  Typically the easiest hair type to manage although colouring, bleaching or heat tools will damage the hair over time, which can make it HP. Do clarify often by not every time, and experiment with protein-rich hair products and layering lightweight moisturising products. 

It’s possible to have a combination of hair types, especially if some parts of your hair are coloured or with heat damage at the ends.  For the water test, try cutting the strand at where the damage begins and test both to see what happens.  A good indicator is also how quickly or slowly different parts of your hair take to dry. 

I hope this gives an added dimension to your hair care.  As you can see there are clear do’s and don’ts for the different hair types.   

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