When it comes to establishing a healthy and beneficial hair care routine, it might not be enough to determine whether you have dry or oily hair and scalp to then simply pick your hair-care products accordingly. Proper care should be based on a deeper factor: your hair’s porosity level.

None of the barbers, even with the most professional hairdressing scissors sets, will be able to make your hair look good if you do not know how to maintain your hair condition once you’ve stepped outside the salon. If you are not familiar with the term, porosity refers to your hair’s ability to absorb and retain moisture in the outermost layer of your hair called the cuticle. To stay healthy, your hair needs to stay hydrated. To penetrate the hair, oils, moisturising products, and water need to get through the cuticles. Hair porosity determines how easy it is for these elements to do so.

Below, you will find essential information to figure out your hair porosity type as well as how to care for different hair types. Let’s get started!

Using a simple glass of water, you can quickly and easily determine your hair porosity. Here are three simple steps:

1. Pour a glass of water.
2. Take a strand of your hair and put it in the glass. But make sure to wash your hair thoroughly before doing this, so there are no remains of hair care or styling products on it.
3. Observe if the strand of hair sinks to the bottom of the glass or sits on top of the water.

And here is the key to interpreting what you see. If the strand floats on top, this means you have low porosity hair. On the other hand, if the hair quickly sinks to the bottom, you have high porosity hair. If the hair floats in the middle of the glass, you most likely have medium porosity hair (or normal porosity).

Low porosity hair is generally considered healthy. It is shiny, not easily electrified, and dense. However, the cuticles are closely spaced, which makes the hair resistant to styling and not great at absorbing moisture. Curls usually fall apart quickly for this type of hair.

Low porosity hair is difficult to wet—in high humidity, it remains normal. This type of hair also tends to accumulate protein-rich hair care products on its surface, which makes it straw-like and heavy. Therefore, it is essential to use very light products with moisturising components that contain almost no proteins, so that they do not make the hair look greasy.

To get more from your hair care routine, you can slightly warm up your hair right after applying a mask or conditioner or simply try a deep-conditioning method.

Medium porosity hair has a slightly loose cuticle layer, which allows it to retain only the necessary amount of moisture. Thus, it keeps hair clear of both excess evaporation and the strong accumulation of moisture. Normal porosity hair, as a rule, keeps styling well and can be chemically curled and coloured with predictable results. It does not require special hairdressing treatments and solutions, but over time, these procedures may damage the hair and increase its porosity.

It is recommended to give normal porosity hair the occasional treatment of restorative deep penetrating conditioners with proteins that bring tangible benefits. Bear in mind that proteins should not be applied in daily hair care as they can also have a negative cumulative effect.

High porosity hair is generally dry, brittle, and fragile. It is usually the result of previous aggressive chemical treatments, excessive heat styling, lack of proper care, environmental damage, or its genetic property (for example, curly hair). When taking care of highly porous hair, it is necessary to use special products (mainly silicone-based), which prevent the absorption of too much moisture. It is even more important in a climate with high temperature and humidity. This will help seal the cuticle and prevent porous hair from absorbing moisture from the air.

Due to its high porosity, this hair type can also easily lose moisture, so it is essential to implement leave-in moisturising conditioners in your hair care routine. These products will help to maintain the necessary level of moisture in your hair. You can also use products rich in protein to help fill in the damage in the cuticle layer and protect the high porosity hair types from losing a large amount of moisture in the long run.

All in all, hair porosity is one of the decisive factors when choosing suitable products for your hair. It is determined genetically, but with the lack of proper care, your hair’s condition may also alter your hair porosity. Things that negatively affect porosity are overwashing, blow-drying and straightening, frequent colouring, and ultraviolet exposure. It is better to avoid such harsh treatments and damaging products to ensure your hair gets enough—but not too much—moisture to keep it healthy.