Shine is a feature that we all look for in hair. Why? Because it conveys the message of healthy hair and gives a boost to the hair’s overall appearance. Other terms often used are gloss and luster which also relate to how light interacts with the hair. There are however many factors that can make hair dull. Let’s discuss.
What is shine?
Shine is often seen as an intense band (usually white) at the crown of the head or at the curvature of the hair. The shine band becomes visible when light hits the hair surface and is reflected back mostly at the specular (S) angle: All reflected rays are in the same direction at the same angle. Some of the light however, enters the hair and gets diffused on the way out (scattered). The amount of this diffused light will dictate how sharp the shine band appears.
Factors affecting the shine of your hair
1. Smoothness of hair surface
Smoothness is probably the most important criteria to create intense shine bands. Think of how well a mirror reflects. There are however many factors that affect smoothness itself:
Sebum from the scalp creates great lubrication on hair but research shows that too much of it actually dulls the hair. This is because it tends to attract dirt or other debris to the hair reducing the smoothness. Keeping the levels in balance (by shampooing at the appropriate frequency) will help to enhance the shine of the hair. Similarly, when the oil is freshly applied, the hair usually looks shinier, but over a day or two, the hair gradually loses that shine.
- Hard water
Soap scum produced from the interaction of your shampoo with hard water deposits on hair and foams a non uniform layer that dulls hair. [Read more here about how to deal with hard water.]
- Cationic conditioning ingredients
Some other research demonstrated that cationic ingredients deposited from shampoos form a non-uniform layer on hair causing irregularities in the surface smoothness. This is not to say that you shouldn’t use the shampoos, but you need to follow up with a conditioner to even out the hair surface.
The increased deposition of conditioning cationic agents can have an adverse effect on hair. Build-ups will reduce the shine of your hair because the layers of conditioner have become uneven. Once in a while, it is important to clarify the hair of existing builds-ups. The shine should quickly be restored after. [Read more here about the signs of overconditioning hair.]
- Chemical treatments
Chemical treatments cause damage to the cuticles. The cuticles become chipped, fractured, lifted and uneven. When light hits the surface, it becomes more scattered. The hair then appears dull and can often be misinterpreted as being dry.
- Hair product deposits
Certain products such as hair spray, dry shampoos, or other products that use resins will cause thick uneven distributions on the hair. Light cannot reflect in a specular way when the surface is that uneven. In addition, combing and other physical manipulations of the resin on the hair produce cracks in the hairspray resins, increasing the diffuse scattering and further dulling the hair.
2. Alignment of hair fibers
Shine is usually easier seen on straight hair because of the fiber alignment. However if you have curly hair, you can clamp a small section of the hair between your fingers making sure the fibers are pulled straight and are aligned. Look at the curved area for a white shine band. The band should be quite visible if your hair is healthy.
3. Color of the hair
Dark hair (natural or dyed) often appears shinier than lighter hair.
In darker colored hair, there are less diffused rays that come out of the hair because part of the light is absorbed into the hair. What we see is mostly specular reflection (concentrated light at the same angle in the same direction). The intensity of the shine band is therefore stronger and the hair appears shinier.