Hair is an incredibly strong fiber - a single healthy strand of hair is actually stronger than a steel wire of the same diameter and can stretch up to 30% of its length when wet before breaking. However, this is only true if your hair is in good condition!
The strength and elasticity of hair (the ability to stretch) comes from the presence of disulfide bonds (strong bonds that hold the keratin protein in your hair shaft) and is also dependent on the moisture (water) content of your hair. This is because moisture allows the disulfide bonds in your hair to stretch and return to normal again - without it, your hair will break every time you brush, blow dry or style it.
Things that reduce the strength and elasticity of your hair and cause it to break more easily include: chemical processing (like bleaching and highlights at the salon), Brazilian keratin treatments , UV exposure, salt and chlorinated water, perms, and overuse of heated styling tools. However, chemical processing may be the worst culprit, as it permanently opens the outer cuticle of the hair, allowing excessive evaporation of water from the hair shaft.
While you can never completely close the cuticle back to where it was, using the right products and daily shampooing and conditioning can do a great job. ELASTICIZER pre-wash treatments can be especially helpful in restoring elasticity and shine and reducing breakage to your hair.
