Hair Structure
Hair has three layers, the cuticle, cortex and medulla. The cuticle is the outermost layer and is made up of keratinized scales. The cortex is made up of two protein layers, sandwiched side-by-side. Both the cuticle and the cortex affect the appearance and texture of the hair. The medulla is the innermost layer and does not affect the appearance or texture of the hair.
Hair Texture
Hair is composed of proteins created by long chains of amino acids. The amino acid chains contain hydrogen, sulfur, carbon and oxygen ions. The ions form water within the hair shaft and create chemical bonds that hold the hair strand together. The ion bonds also determine texture and curl pattern.
Hair has three types of bonds: hydrogen, salt and disulfide. Salt and hydrogen bonds are relatively weak and are easily broken with heat and moisture. Disulfide bonds are much stronger and can only be broken with a chemical agent.
How a Curling Iron Works
A curling iron is a heated cylinder with a flat piece of metal that acts as a guide and place holder for the hair. When you apply a curling iron to a strand of hair, the heat from the iron temporarily breaks the hydrogen and salt bonds in the hair. As you wrap the hair around the iron, you retrain the hair to follow a curved pattern. The larger the cylinder, the larger the resulting curl. When the hair cools, the hydrogen and salt bonds re-form into the new, curved pattern.
Successful Hair Curling
Hair curls best when divided into small sections because smaller sections allow the even distribution of heat. If the sections are too big, or too thick, the outer strands will insulate the section and prevent heat from penetrating to the interior of the section. The curl needs to cool completely for the hydrogen and salt bonds to set in their new pattern. Avoid touching or styling the curls until they have completely cooled. The retrained hydrogen and salt bonds are also sensitive to moisture, which is why curls tend to fall in humid conditions. Using a product to protect against moisture helps maintain curls longer.
Member Comments