Who doesn't love shiny hair?/p>
Many of us desire shiny waves and curls. But most of us probably don't know why hair shines, or why it doesn't. The answer is more complicated than one would think.
Each hair has a cuticle, which acts as a mirror that reflects a certain ratio of light—the higher the number of layers, the higher the ratio of the reflected light and the more intense the shine.
Shine is perceived in two parts: the Chroma-Band, which reveals the color within the hair shaft, and the Shine-Band, which is a pure reflection of the light off of the hair's protective coating.
"The physics of hair shine really is the reflection of light not just off the cuticle but through your cuticle," explains Dianna Kenneally, a principal scientist at P&G Beauty (a division of Procter & Gamble). "The light actually goes through the cuticle, absorbs the color of your hair and comes back.
But making your curls shine may be a challenge because factors such as the structure of the hair, sebum buildup, styling products, damage from heat or chemicals, dirt and pollution all can interfere with shine.
"If you have layers of materials, it interferes with the ability of light to go through the hair shaft," Kenneally says. "If the hair shaft is damaged and the cuticle is roughened, light won't reflect back strongly. It's diffuse."
The right style and color also can enhance shine.
"For maximum shine, hair must all be going in the same direction," she says. "Defined curls give you more shine than a lot of little curls because of the nature of the way your eye sees shine."
To achieve this with curly or wavy hair, she suggests styling the hair in sections to create bigger curls.
A good color treatment also can enhance shine because it intensifies the color inside the cortex of the hair. When the light comes in and reflects back out, you see the shine more intensely. The darker the color, the more intense the Shine-Bands.
"That's why black hair looks so shiny," Kenneally says. "It's because the contrast between the Chroma-Band and the color is so intense."
Anything that helps protect the cuticle and encourages it to lay down will enhance shine, Kenneally says.
Fatty alcohols—moisturizing alcohols—actually protect the cuticle and keep it intact, she says.
Kenneally also is a big fan of silicones, which lay on the top layer of the hair to keep the moisture in. Silicones have been a hot-button item for people in the curly world, but Kenneally believes they are one of the most powerful tools to enhance shine.
"Farmers use this technique in arid areas, putting edible oils in their ponds to prevent them from drying up," she says.
Silicones also reduce friction, protecting the hair from damage caused by heat appliances and brushing. Silicones are most effective in conditioners and styling products, she says.
But silicones must be used in moderation because overuse can make the hair sticky and heavy and may cause buildup, which dulls the hair. Many hair experts suggest using water-soluble silicones, which can be rinsed away without having to use harsh sulfates.
According to a recent study, there is actually a scientific reason why we are attracted to shiny hair.
The International Congress and Symposium Series last year published "Assessment of Hair Quality Using Eye-Tracking Technology," sponsored by an educational grant from P&G Beauty. People were shown photos of people with different types of hair (messy, frizzy, straight, curly, etc.) and a laser—developed for fighter jet pilots—tracked how much time they spent looking at different elements on the computer screen.
"What we found is that when people had shiny hair, the eyes would look at the shine band and then would move on to the face," Kenneally says. "When people had dull, frizzy hair, a lot of time was spent looking at the frizzy elements. It was distracting. If you've got frizzy, messy hair, it can distract from your face."