Science of Curly Hair

The Follicle
Whether hair is curly or straight is determined by the shape of the hair follicle.

Natural curly hair tends to be more fragile than straight hair. Due to the uneven shape of the hair fiber, the hair shaft can have “high spots” where the cuticle is slightly lifted compared to the rest of the hair fiber. When the cuticles are lifted, the internal structure becomes exposed, leaving the hair vulnerable to damage and dehydration.

Ellipticity refers to the degree of flattening of a circle. When the ellipticity increases, the degree of curl increases, along with the hair’s fragility

High Humidity
Curly hair is especially susceptible to humidity because it’s naturally more porous than straight hair. Dry hair exposed to a very humid environment will gradually swell with water molecules. As this happens the hair may lose its shape, becoming fuller and frizzy.
Due to its shape and curl pattern the hair can become entangled, which leads to breakage when detangling. Also, curly hair swollen by excess water can lose its curl pattern, creating shapeless curl and unwanted frizz.

Low Humidity
Curls exposed to very dry air without protection can lose their moisture, making hair prone to breakage and split ends. The result is an uneven texture, which may be hard to control, due to its flyaway nature.

What Curly Hair Needs

Curls’ coils make it harder for hair’s natural oils to coat and moisturize each strand. Curly and wavy hair by nature are drier than their straight hair counterparts. The shape of the follicle affects the way curly and wavy hair receive moisture in the form of lipids or the natural oils secreted from the scalp. When determining the amount of moisture, consider the diameter and abundance as well as curl formation

Due to its twists and turns, curly and wavy hair reflects light differently than straight hair. Naturally curly hair is rarely able to achieve the same level of shine as straight hair because light can become absorbed inside the spirals of the curls or along ruffled cuticles.

Curl Definition
Curl definition refers to the overall appearance of hair and how the curl holds its shape. When enhancing curl definition it’s important to consider the condition of the curls, as well as the right cutting and styling techniques.

Personality of Curls

The size and shape of curls can vary from head to head. There may be a mix of different curl patterns within the same head of hair. Although there tends to be a predominant curl pattern, people with natural curls have an average of 2-4 different types of curls. It’s possible to have curls that are tighter at the scalp area and gradually become looser or even straight toward the ends. It’s also possible to have straighter hair that becomes gradually wavy or curly toward the ends.


Bounce-Back Factor
The bounce-back factor is hair’s reaction when pulled down into a straighter position and released. When the curl is stretched until straight, the actual length may be up to twice as long. It helps you determine how much to cut, especially in the fringe area.

Structure refers to the physical characteristics of hair and its support. Curly hair strands take up more space than straighter hair and offer each other support, increasing the volume and changing the structure of the shape. As the degree of curliness increases, so do the fragility. Likewise, when the degree of curliness increases, so does the amount of volume or 3D space the curl takes up. This can significantly alter the structure of the overall shape or design.

Shape refers to two things: the individual shape of the waves or curls, and the overall shape or silhouette of the design.
The individual shape of the waves or curls: Are they large and loopy? Wide and open? Do they bend, or twist? The individual shape helps determine curl type, method, technique of cutting and styling. The overall shape or silhouette of the design: does the overall shape have a “shelf” appearance? Does it suit the shape of the face and complement the curl pattern? The overall shape helps determine cutting and styling techniques.


The length of hair can have an impact on how curls and waves behave. When they’re dry, chemically altered or distressed, the structure and curl pattern are affected. Once the hair is cut or damaged areas removed, it’s as if the curls spring back to life. A little cut can go a long way. The length of the hair can also affect how much weight is on the curl. Longer lengths may work best for thicker spiral types, while shorter layers may be best for finer, wavier types.