Learn how elasticity affects your ability to style your hair and maintain your curls.

How to Improve Hair Elasticity

We have learned that hair elasticity is heavily dependent upon two key factors: 1.) hydrogen bonding between water molecules and keratin strands and 2). disulfide bonds between adjacent cystine amino acid groups, both of which are dependent upon preservation of the protein structure and hydration of the cortex. The best approach to ensure excellent elasticity is to maintain an intact protein structure inside the cortex and an adequate level of hydration.

In an ideal world, prevention of damage to the cortex protein structure is achieved by maintaining a pristine cuticle layer, avoiding high temperature treatments and processes, avoiding chemical processes such as color, permanent waves and relaxers, minimizing UV exposure, limiting hygral fatigue (excessive water exposure), and using only the most gentle mechanical forces for combing and styling. Of course, we don’t live in an ideal world, so most people will experience varying levels of degradation of the internal protein structure of their hair, accompanied by a gradual deterioration of the desirable elastic properties. Minimizing exposure to destructive processes and frequent trims helps defray damage, as does use of a good deep conditioner and gentle treatment of hair at all times.

The use of protein treatments and protein-containing conditioners is often recommended to help improve or restore elasticity. This approach can be useful for those who do have damaged proteins in the cuticle structure or within the hair shaft. Hydrolyzed proteins in these products are in amino-acid form and lower molecular weight poly-peptide form, and can penetrate the cortex. They are retained there in subsequent washings and can contribute to hair strength and integrity to some extent, preserving the tendency for elastic, reversible deformations at low stresses. However, it is most likely that these materials act only as a patch over a hole rather than actually assimilating themselves into the protein strand and fibrillar structure. One word of caution about these types of treatments is that they can potentially contribute to brittle behavior (breakage) if used in excess or if the hair already has sufficient protein content.

For a substance that seems mostly decorative, hair never ceases to amaze me in its complexity. The intricacies of this biopolymeric composite are simply amazing. The elastic properties of healthy hair can serve us well and allow for much versatility in our coiffure, if proper care is taken to keep hair in the best shape possible.

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Tonya McKay

Tonya McKay Becker is a curly-haired polymer scientist and cosmetic chemist whose academic and industrial research experience have provided her with expertise in the fundamentals and applications of polymer science and colloid chemistry. She has long had a fascination with the structure-property relationships of the complex solutions used in hair and skin care products, and how they interact with and impact these remarkable biological substrates. Ever curious, Tonya has dedicated herself for more than a decade to honing her expertise on the science of curly hair, how it differs from straight hair, and how product ingredients used on curly hair affect its health and beauty. Her passion for sharing this knowledge with others has led to her current career of educating people from all backgrounds who share an interest in this exciting field.

Great article. I never thought to apply the P=F/A formula to hair. Makes total sense