Hair Fundamentals
HAIR FUNDAMENTALS LOOK & LEARN What you need to know to color and style like a pro.

Hair Structure

Hair is composed of an insoluble protein called keratin. Every hair strand is made up of 3 areas:

Cuticle- The outermost layer of hair, comprised of overlapping flat, colorless cells, much like the shingles on a roof. The cuticle contains no pigment.

Cortex -This is the cell layer between the cuticle and medulla that contains varying amounts of two natural color pigments that determine a persons natural hair color. The cortex also determines hair strength and texture. This section of the hair is most affected by permanent hair color because it is where natural pigment is lightened and new, artificial pigment is deposited.

Medulla -The medulla is the hollow center or pith of the hair shaft. It does not appear in all hair and has no apparent function. It contains no pigment.


Porosity is the ability of hair to absorb moisture.

It is a key factor in determining how the hair will accept and hold color. Common causes of porosity include chemical services such as highlighting, permanent hair color and chemical relaxers; environmental elements like the sun and wind; and mechanical treatments, including flat irons, blow dryers and curling irons.

It is important to understand your client's lifestyle as it contributes to the porosity. If she is outdoors often in the sun and wind or frequently uses heat to style her hair, you must take this into consideration as you determine how to formulate (i.e., make product choices) and what technique you will use.


Texture is the diameter of the hair shaft, typically defined as fine, average (or medium) or coarse.

Texture is not related to a wave pattern. For example, both fine and coarse hair can be curly or straight.These are general examples of various textures based on natural hair color or type.

Remember, they are general descriptions only, but they can be used as a reference point to help identify texture: