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How Does Hair Straightening Work?

Updated: Dec 16, 2020

Have you ever wondered how your hair can go from curly to straight or vice versa? It's all about the bonds that hold your hair structure together.

If you haven't yet read the article Why is Curly Hair Curly? I highly recommend you do, as we will be expanding on some points spoken about there.

Hydrogen bonds

Most of you have probably come across hydrogen bonds in your chemistry or biology classes - they're pretty simple and abundant in our every day lives.

They form due to the difference in charge between the delta negative oxygen atom and delta positive hydrogen atom - across molecules. These intermolecular bonds are easily broken by two factors: water and heat.

Water and hydrogen bonds

Hydrogen bonds can be broken by a change in humidity or water content.

Water can form two hydrogen bonds per molecule - so when it's mixed with your hair - it will break the bonds in between hair strands to form them with water itself.

This is why your hair will not retain the same shape after a shower.

Heat and hydrogen bonds

Hydrogen bonds can also be broken by a change in kinetic energy (or heat).

When you apply heat to your hair, the hydrogen bonds break due to excess kinetic energy. The bonds vibrate so much that the intermolecular bonds fall apart, back to their original molecules.

Hair straightening

Achieving a desired hairstyle is all about breaking hydrogen bonds, and re-forming them in just the right way.

Hair straighteners or curling irons use heat to break bonds. You apply the heat in the way you would like the hair to stay, because the change in temperature will make the hydrogen bonds re-form and the shape will stay that way.

It's all about a change in heat or a change in humidity which dictates what your hair will look like.

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