All Curls Are Not Created Equal- Part 3

Thursday, June 18, 2009 Posted by Karen


HAIR TEXTURE

Straight. Curly. Wavy. Kinky. These are the words that used to come to my mind when I thought of the term "hair texture".

Once I started this hair research journey, however, I learned that my terminology needed some tweaking.

"Wave pattern" is a more appropriate term for describing the visible shape of a hair strand. This is where Andre Walker's hair typing labels would come into play- 3A, 3B, 4A, etc...

"Hair texture" is actually the term used to describe the circumference of a hair strand. This is where the descriptions coarse (thick strands), medium (normal strands), or fine (thin strands), would come into play.

Coarse hair generally has all 3 structural layers-- the cuticle, the cortex, and the medulla.
It is the strongest type of hair, and tends to resist breakage and chemical processing. Asian hair is generally described as coarse, as it has the widest diameter. (While you can be of any race and have coarse hair, the geometrical shape of the cross-section of your hair will vary, dependent on your race, and will contribute to your hair's integrity-- more on that later.)

Medium hair also has all 3 structural layers, generally speaking. This is what would be described as "normal" hair. There are no special considerations to be made for styling normal hair. It is responsive to heat and chemical styling, but is not overly prone to damage. You can be of any race and have medium or normal texture hair.

Fine hair usually has only 2 of the structural layers-- the cuticle and the cortex. This is the weakest type of hair, easy to chemically process, but more susceptible to heat, traction, and chemical damage. As discussed in my last post, the function of the medulla (the innermost portion of the hair) is not yet well understood. However, you can understand how its absence contributes to the relative weakness of fine hair compared to medium or coarse hair. You can be of any race and have fine hair, though blond Caucasian hair tends to be the finest.

It is possible to have all 3 hair textures in different sections of your hair.
There is nothing you can do to permanently change the texture (diameter) of your hair.

Thickening shampoos deposit product that will temporarily adhere to your hair, giving it a thicker appearance.

Henna binds to keratin in the hair, and can also temporarily make it thicker, though repeated use can maintain the thickness (but it can also lead to brittle hair if you don't deep condition regularly).


The Cross-Section

Now, while there is a visible shape to the hair strand (the wave pattern), there is also a shape to the hair strand that is not visible to the naked eye.

This is the shape of a cross-section of the hair shaft.


Photobucket
http://www.optics.rochester.edu/workgroups/cml/opt307/spr06/xue/project.htm

Asian hair, which generally has the thickest diameter, has a circular cross-section. This shape is usually consistent throughout the length of the hair strand, contributing to its strength and ease in grooming.

Caucasian hair has an elliptical cross-section. This shape is also consistent throughout the length of the hair strand, contributing to its strength and ease in grooming.

African hair has a flatter elliptical cross-section than Caucasian hair (not so easily seen in the image above), and can be flat like a ribbon in some sections, especially where the hair bends and kinks. This variety of diameter and shape along the hair strand contributes to the vulnerability of African hair, rendering it more susceptible to grooming damage than Asian or Causcasian hair.
Because of all of the bends and twists in African hair, it also has a tendency to fold over on itself, creating.... ya-ta-ta-TAAAA.... CURLY KNOTS!!!

What? Did you guys think I made it up? Well, so did I! That is, until I came across this image...

Curly Knots
http://www.pg.com/science/haircare/hair_twh_76.htm

The caption beside the picture literally read, "Knotting associated with African hair".

Well, ya don't say?

Raise your hand if you needed a microscopic photo to tell you that you have curly knots.
I didn't think so.

HAIR DENSITY

This term simply describes the number of hair strands on a person's head, or per square inch.

The average human head has 100,000 hairs, or 2200 hair strands per square inch.

Interestingly, studies show that races with thicker hair diameters (Asians) tend to have lower hair density, and races with thinner hair diameters (natural blond Caucasians) tend to have higher hair densities.

I guess the overall look of our hair was meant to "average" out. Neat, isn't it?

There is nothing you can do to change the density of your hair, other than getting hair plugs (youch!). Extensions and a GOOD weave can also lend to the appearance of denser hair, as long as bad styling doesn't overshadow it.

HAIR POROSITY

The term "hair porosity" refers to the ability of your hair to absorb moisture.

Hair is naturally porous, allowing moisture to come in and come out through the cuticle layer. Hair can be described as having, low, normal, or high porosity.

Photobucket

The cuticle should normally lay flat, with a slight bending at the edges, to faciliate normal moisture exchange.

If the cuticle is compact, the hair may not absorb moisture easily, and may be resistant to heat and chemical treatments. If the cuticle is raised too much (highly porous hair), it will absorb or lose moisture too readily, and may be overly sensitive to heat and chemical treatments.
The goal is to have hair with normal porosity, so that it will maintain an adequate moisture balance.

A quick porosity test- pull a couple of hair strands from different parts of your hair, and then drop them in a cup of water. If they sink within 5 - 10 seconds, then your hair is overly porous (mine hasn't sunk more than an hour later. I don't know if that's really good, or really bad. But it was a lot of fun to watch it curl up on itself after 10 seconds or so)

If the hair is highly porous, the use of protein treatments and/or an acid balanced shampoo can help. Don't overuse protein treatments, however, or your hair will get "crunchy" and brittle. (The Aphogee Two-Step Protein Treatment, for instance, should be used no more often than once every 6 weeks).

Phew!!!

I'll give you guys a break for today. We'll pick up on hair elasticity and summarize all of this hair science in part 4 of "All Curls Are Not Created Equal".

Till then,
Karen

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