What causes shrinkage?
Shrinkage is the result of two factors:
- The natural shape of the hair shaft
- How hair reacts to water
Factor 1: Hair shaft shape
Hair’s shape is controlled by the curvature of its follicle. If the follicle is curved, the hair emerging will be curled. If the follicle is straight, the emerging hair will be straight. In addition to this, the growth of curly and coily hair shafts undergo asymmetrical keratinization creating a tension that results in twist and curves.
The hair shaft itself is composed of proteins (keratin) that are attached to one another by three different types of bonds: hydrogen, salt, and disulfide. These side bonds link together and play a major role in the elasticity and strength of hair.
Both hydrogen and salt bonds are physical bonds that can be broken fairly easily. Hydrogen bonds can break once they come into contact with water or heat. Whereas salt bonds are pH sensitive and can break once they come into contact with acidic or alkaline solutions. Disulfide bonds are different from salt or hydrogen bonds because they require a chemical reduction or oxidation to change their formation. Take a relaxer for example, once the solution is applied to the hair shaft it begins to break and ‘relax’ the disulfide bonds. Once these bonds are broken they are unable to reform again, causing the straightening process to be permanent.
Factor 2: Water intake
When hair is exposed to water its hydrogen bonds can easily break causing its shape to change. As a result, the hair shaft becomes more elastic and easier to reshape. This is why curls are looser when hair is damp and is generally easier to restyle.
Once hair dries, new hydrogen bonds are spontaneously rebuilt into the new shape created when styling — whether it’s with rollers, brushing, or twists/braids. Your hair temporarily holds onto a shape memory of your new style, but as soon as hair is exposed to water (think humidity and water-based hair products) these weak, hydrogen bonds will break again and cause hair to return to its natural shape.
And here’s the kicker — your porosity level plays a major role in how much water your hair absorbs, especially when it comes to your environment. Using humidity-resistant hair products can help block unwanted moisture and will help you to maintain your style.
Love or hate it, shrinkage happens! If you’re not a fan of it for any reason, there are styles you can do to elongate your strands. Work your hair, don’t let it work you.
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