Split ends are a common enough hair complaint, but do you know what precisely is splitting, and how, and why? In order to answer these questions and more, a quick hair anatomy lesson.
Each strand of hair on your head is composed of three layers. The innermost of these layers is called the medulla. It contains melanin, and it's what gives your hair its color. The next layer out is the cortex. It's composed of long coiled proteins called keratin, which give your hair its strength and texture. The outermost of the layers is the cuticle, which consists of dead cells overlapping each other like tiles on a roof. Like a roof, the cuticle shields what's underneath from damage from the elements.
Most of our hair complaints are the result of the wearing away of the cuticle. Heat from the sun and hair styling appliances, as well as chlorine and salt water are common culprits. Since the cuticle is what reflects light to give hair shine, this shine is one of the first things to go when the cuticle is worn away. As the middle layer, the cortex, is exposed, its protein fibers can unravel, causing the hair to split, hence, split ends.
Once you have split ends, the only thing that will get rid of them is a haircut. After that, to reduce the risk of future split ends, turn down the hair dryer's heat, especially if you have fine hair, which is more susceptible to breakage. If you must blow dry, use a medium or cool setting.