I want to talk about something that changed the way I think about hair completely. Not a product. Not an ingredient. A concept. And once you understand it, you will never look at your hair the same way again. It is called porosity.
Your hair has an opinion about moisture
Porosity describes how your hair absorbs and holds onto moisture. And it turns out, not all hair does this the same way. Think about a pine cone. When it is wet or warm, the scales open up. When it is dry, they close back tight. Your hair works in a similar way. The outer layer of every strand is covered in tiny overlapping scales and depending on how open or closed those scales are, your hair either drinks in moisture easily or resists it. It either holds onto that moisture or loses it almost immediately. That one thing, how open or closed your cuticle is, explains so much. Why some products work for your friend but do nothing for you. Why your hair feels dry again an hour after washing. Why humidity turns everything to frizz before you have even left the house.
There are three reference points but your hair might sit anywhere in between
Hair porosity exists on a spectrum. We usually talk about it in three broad categories low, medium and high but most people sit somewhere in between, and it is very common to have different porosity at your roots than at your ends, especially if you colour or use heat regularly.
Low porosity hair has a tight, closed cuticle. Water and product take a long time to absorb you might notice your hair takes forever to get wet in the shower, or that conditioner sits on top rather than soaking in. The upside is that once moisture is in, it stays.
High porosity hair has a lifted or damaged cuticle usually from colour, heat styling, chemical treatments or just time. It absorbs everything instantly but loses moisture just as fast. If your hair feels dry again quickly after washing, if humidity hits it immediately, if no product ever feels like quite enough this is likely you.
Medium porosity is the balanced middle. Hair absorbs and holds moisture well. Most routines work. Products tend to do what they say. But remember these are reference points, not boxes. Read your hair, not a label.
Here is what nobody talks about enough
Not all hair that behaves like low porosity actually is low porosity. Hard water, water with high mineral content, very common across Sweden and most of northern Europe leaves calcium and magnesium deposits on the hair over time. These coat the cuticle from the outside, making hair resistant and heavy, making products sit on top, making absorption feel impossible. It looks exactly like low porosity. But it is not. The same goes for metal deposits from tap water and old product buildup that has never been properly removed.
By now you probably have a feel for where your hair sits. The signs are usually there once you know what to look for.
If you are unsure whether you have true low porosity or just buildup start with a deep cleanse or a chelating treatment. Reset the hair first, then see how it behaves. You might be surprised. Porosity is not a trend. It is just your hair telling you what it needs. Once you learn to listen, everything gets easier.
Always rooting for you,
-Sarah/Staunch