If you want to sound nerdy to your next science-inclined client or you’ve just gotten a little hazy on the chemistry of hair, read on for a quick run down!

Hair Science 101: Chemistry Lesson

A chemical bond is a mechanism that links two or more chemical elements to create a larger structure. In the context of hair, the most relevant bonds to study are the ones in the cortex layer of strands (the cuticle is primarily a scaly outer layer and the medulla, the innermost, does not typically participate in styling services). Understanding bonds that make up hair is vital to hair styling as an art. 

There are primarily three types of bonds that each contribute to about a third of the overall mechanical strength and nature of hair. ‘Hydrogen bonds’ are the most populous and also the easiest to manipulate. Exposure to water or heat easily breaks them and they readily reform when those agents are taken away. This allows for bringing about temporary styling of hair easily. 

Image 1. Hydrogen bond

The second type, ‘ionic bonds,’ are more chemical in nature in that they require a solution which is significantly acidic or basic in pH to break them. These bonds are stronger than hydrogen bonds and are fewer in number as well. A good understanding of the chemical nature of styling products and their resultant pH levels is critical to effective manipulation of these bonds. They can be reformed by restoring pH to the natural level (slightly acidic). 

Image 2. Ionic bond

The third and strongest bond is referred to as disulphide bonds or simply, sulphur bonds. They are inherently the most stable and hence the hardest to break. These are fewest in number but are just as important to understand since they are primarily responsible for the elasticity of hair. High heat such as that from flat irons or strong chemicals like relaxers can break these bonds. Neutralizing agents are required to add disulphide bonds back but these are new bonds since the original ones can never be reformed once broken. 

Image 3. Disulphide bond

Broadly, avoiding excessive heat-styling and harsh chemicals on hair can help preserve bond integrity. Additionally, using bond building products and regular deep conditioning treatments can help maintain optimal hair chemistry for bond health.  

About Melanin

It would be remiss to not touch on hair pigment while discussing hair chemistry. Melanin is the hair pigment present in the cortex of the hair that is responsible for its natural color. Melanin is produced within the hair follicle by specialized cells called melanocytes. Melanin lives in the cortex of hair and consequently, new pigment needs to be injected into this layer or naturally occurring pigment needs to be stripped away from this layer during hair color services. 

Melanin is of two types - Eumelanin is the dark colored subcategory of melanin and Pheomelanin is the lighter colored version. The type and proportion of melanin produced clearly varies from person to person but can also vary from one part of the scalp to another on the same head and can also change over time. 

Your genetic makeup largely determines the amount and ratio of melanin in your hair. For example, black hair has large amounts of eumelanin whereas red hair has mostly pheomelanin and only some eumelanin.

In addition to providing color and structure to hair, melanin helps protect hair from harsh ultraviolet rays in sunlight. Typically, melanin production declines with age and causes greying (around middle age for the average person). A diet rich in antioxidants and protein as well as supplements Vitamins B6 and B12 are said to support melanin generation. 

Understanding the underlying chemistry of hair goes a long way in making sure that you and your client get the desired outcome with coloring and styling services every single time! 

 Tej Belagodu is a hair enthusiast and entrepreneur. During the Covid19 pandemic, he developed an online marketplace where clients could buy customized DIY hair color kits formulated by licensed stylists based on a video consultation. He is currently exploring a couple of new ideas in the hair industry and evaluating their viability. Occasionally, he writes articles on various topics related to hair. At his day job, he is an Engineering Manager in the manufacturing organization of a semiconductor technology company. He has a Master of Science degree in Electrical Engineering from Arizona State University. Tej can be reached at tej.belagodu@gmail.com.