Hair Porosity

Porosity in its simplest form relates directly to the ability, or inability for hair to absorb water

or chemicals directly into the cortex. All hair is naturally permeable and porous to water.

However, the degree of porosity will vary by the individual, the condition and shape of the

hair’s cuticle layers. If your hair faces a traumatic styling event such as chemical relaxing or

permanent coloring, the protein structure is attacked and the protective cuticle shielding

becomes ragged and torn. Therefore, hair in this condition is said to be porous.

In order to glean more knowledge, it is useful to visualize hair as a wooden fence. A new

fence is durable and has the capacity and ability to shield the yard it surrounds. The new

fence can endure rain, sun, storms and the majority of the elements which may be thrust

upon it. Overtime as the fence ages, the wood in the fence begins to soften, and the fence’s

once protective barrier becomes vulnerable and can be breached. Often, holes may

appear in the fence or some planks may become missing. The fence has become porous.

This example relates to how our hair functions. When aging, the protective cuticle layers

begin to peel, crack and lift away. A change in the presentation of the cuticle’s shape

makes the hair less durable and able to absorb and hold the moisture it vitally needs.

Thus, older hair is more porous and has higher porosity, than the newer hair. Porosity

increases as we move from the roots to the ends of the hair as this represents age

progression along the fiber.

Hair will not readily absorb moisture and resists chemical treatments if it has

low porosity.   This type of hair is generally quite healthy and has not been exposed

to cuticle-degrading treatments. In low-porosity hair, the cuticle imbrications

and/or or ridges along the hair shaft are tightly shut just as when the hair first emerges

from the hair follicle. The assault on the hair due to everyday living, chemical processes

and styling eventually takes a toll on the cuticle scales and causes them to lift and lose their

tightness over time. Black hair has been known to have low porosity naturally.  It is usually

less porous than Caucasian or Asian hair types etc, unless it has received chemical process.

You will often find that the majority of individuals will have hair somewhere in the middle

of the two extremes of porosity: a.) Hair with good porosity that retains moisture well

and b.) Hair that accepts chemical treatments like coloring or relaxing if desired.

There is an intricate connection between the hairs pH balance and porosity.  As such,

Low-pH products and styling treatments diminished the hair’s porosity by constricting

the cuticle causing it to tighten. However, high-pH products have the opposite effect

and increase the hair’s porosity by swelling and lifting the cuticle scales.