What best describes elasticity?

• A. The ability of the hair to stretch and return to its original shape
• B. The hair's porosity
• C. The strength of the hair shaft
• D. The rate of hair growth

Answer: (A)

Elasticity describes the hair’s ability to stretch under tension and then return to its original length when the force is released. This property reflects the health of the hair’s protein structure and moisture balance; yes to a strand that can elongate and snap back, and no to one that sags or breaks instead. A simple way to gauge it is to gently pull a damp strand and see if it returns fully to its starting length. If it does, elasticity is good, meaning the hair can handle styling and chemical services with less risk of breakage. If it doesn’t, elasticity is low, which signals potential damage or over-processing. This concept is different from porosity (how easily moisture passes into the hair), from the overall strength of the hair shaft (how much force it can withstand before breaking), and from the rate of hair growth (how fast new hair is produced).