What’s up with Roller Setting?

What’s up everyone? I finally got myself together to start my hair science series. 😀 The first topic is near and dear to me – the science behind roller sets. If you read this blog, you already know about my love of the roller set. At least 80% of my wash day posts feature a roller set. Before we start, I have a little disclaimer. I am not a hair scientist, dermatologist, trichologist or anything like that. I’m just someone who loves science and hair and I want to share it with you.

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Alright. As you may or may not know, hair is primarily made of protein. The building blocks of proteins are called amino acids. There are 4 major types of bonds (how atoms/ions connect together) in the hair strand.

The middle layer of the hair, the cortex, is made up of millions of polypeptide chains (many amino aci cross-linked with each other by three different types of side bonds

  1. Peptide bonds – The connections between the amino acids.
  2. Disulfide bonds (disulfide bridges) – The connection between two polypeptide chains (many amino acids). The strongest bond and can only be broken by a chemical process, like a relaxer.
  3. Salt bonds – Formed by the attraction of positively and negatively charged amino acids. They are affected by changes in pH (acidity and alkalinity)
  4. Hydrogen bonds – A weak attraction between oxygen and hydrogen. Hydrogen bonds can easily be broken by water or heat.

Out of the three type of side bonds (disulfide, salt, and hydrogen), hydrogen is the weakest.

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Various types of side bonds in hair

When you wet your hair, the hydrogen bonds are broken and the other bonds stay intact. When hydrogen bonds break, the shape of the hair changes. As your hair dries around the roller, the hydrogen bonds are formed again. If the wet hair is then wound on to rollers it will form a new shape, and if it is dried on the rollers it will keep this shape.

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Side bonds when introduced to water

Think about what happens when you roller set (or wet set) your hair. You separate your hair, spray with water or setting lotion, roller set the hair and make sure it’s dry. Once you remove the roller or undo the set, your hair is curly. It usually stays curly until you wash your hair again or you get caught in the rain. Your curls may not stay if it’s very humid (hint hint – rainy season) because there so much water in the air. The water vapor breaks the hydrogen bonds which changes the shape of the hair which leads to frizz time. 🙁

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So there you have it, the *very* basic science behind roller setting. If you like this post or have any suggestions for another topic, please leave a comment below.

Sources:
  • FRIZZY HAIR, CURLED HAIR: PLAYING WITH SHAPES [Hair-Science.com]
  • Hair Strength [P&G Beauty & Grooming]
  • Hair Composition – [Design Essentials]
  • Chapter 1: Scalp and Hair Structure, Function, and Characteristics from The Science of Black Hair: Comprehensive Guide to Black Hair Care by Audrey Davis- Sivasothy