All Curls Are Not Created Equal- Part 2

Tuesday, June 16, 2009 Posted by Karen


In "All Curls Are Not Created Equal- Part 1", I told you about the hair typing system that Andre Walker developed.

Based on that system, you should have been able to determine your curl category:

3A- loose defined curls with natural shine
3B- medium corkscrew curls with some natural shine
3C- tighter corkscrew curls with some natural shine
4A- tight kinky curls with little natural shine
4B- tight kinky curls with little to no shine, and little to no definition

(visit my last post to view pictures of these curl types)

But knowing your curl category is only a smidgen of what you need to know to truly understand your hair.

BASIC HAIR STRUCTURE

hair cross section

Each hair strand consists of 3 different layers

The Cuticle
The Cortex
The Medulla

The Cuticle

This is the thin and colorless outermost layer of the hair shaft. Its purpose is to protect the innermost part of the hair. It has a "scaled" appearance (like shingles overlapping on a rooftop), and runs along the length of the hair, from root to tip. Due to the overlapping, the thickness of the cuticle generally ranges between 5 - 10 layers.

Asian hair generally has a thickness of 10 or more layers.
Caucasian hair generally has a thickness of 4 - 7 layers.
African hair generally has a thickness of 7 - 11 layers*.

*Important note- Where African hair "kinks" or sharply bends & twists, the cuticle layer is compelled to lift, exposing the inner part of the hair to the elements. Also, the cuticle layers are generally thinner at the kink, and can be as thin as 2 layers, making the hair more vulnerable to damage and breakage.

The Cortex

This is the middle layer of the hair shaft, and gives the hair strand its elasticity, strength, and shape. It also contains the melanin that gives hair its color.

The cortex occupies 75% of the hair strand, and is made from different types of cells, the main of which are paracortical cells and orthocortical cells.

The cortex in Asian hair is made exclusively from the paracortical cell type.
The cortex in African hair is made up of equal rows of both the paracortical and orthocortical cell types*.
The cortex in mixed race hair is generally made mostly of the paracortical cell type with narrow rows of orthocortical cells.

*Important note- Orthocortical cells have less thermal stability than paracortical cells. This means that African hair can be damaged by heat more easily than Asian hair or any other hair type that contains a higher proportion of paracortical to orthocortical cells.

The Medulla

This is the innermost layer of the hair shaft (we don't know what its purpose is).

In hair with a larger diameter (coarse* or thick hair), the medulla is usually continuous throughout the length of the hair strand (rarely, except in individuals of Asian descent).
In hair with a smaller diameter (fine or thin hair strands) the medulla may be discontinuous (fragmented) or absent altogether in the hair strand.

*Important note- Often times, the word "coarse" has been used to describe curly or kinky African hair. However, the word "coarse" really describes the THICKNESS or diameter of hair strands. As a person of African descent, your hair may be coarse or fine, regardless of how curly or kinky your hair appears.

Lesson Learned

African hair has more curls and kinks along the hair shaft than Caucasian or Asian hair.

It also has fewer cuticle layers where those curls and kinks take place, making it more vulnerable to damage.

Because of the make-up of the cortical layer in African hair, it is more susceptible to heat damage than Asian or mixed hair (and because of the texture of African hair, we are more likely to expose our hair to high temperature heat for styling purposes).

African hair is made up of the same substances as Asian or Caucasian hair, but at different proportions.

And considering that the majority of African-Americans have a mixed race heritage , your head could contain any number of ethnic "tendencies" in any given section.

In part 3 of the "All Curls Are Not Created Equal" series, I'll discuss hair density, texture, porosity, and elasticity.

See you then!

-Karen

1 comments:

  1. jettiemae said...

    Thank you soooo much for taking the time to research and post this series. It's very informative and very much appreciated!

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