Before going into heat styling, we should first know what hair is and what it is made up of.
Hair mainly consists out of strands of the protein, keratin. These keratin strands are held together by different types of bonds. These bonds are disulfide bonds (they don’t break during heat styling), salt bonds, hydrogen bonds, and van der Waals forces.
These bonds contribute to the shape, strength, and elasticity of the skin. When heat styling, the hydrogen bonds are broken down and reformed. There are other bonds that are not reformed during heat styling, but the shape of your hair will still change as there are many hydrogen bonds.
Hydrogen bonds can be broken and reformed, giving your hair another shape. For example, when you wet your hair, the water causes the hydrogen bonds to reform. This is also how you can create curls with your wet hair.
Heat can also break hydrogen bonds. Then you can change the shape of your hair with the plates of the curling iron, It then cools down, and the structure of your hair changes (it becomes straightened or curled). When you wet your hair again the hydrogen bonds are reformed again and comes back to their original shape.
How is Heat styling causing damage to your hair?
It is because heat styling can decompose the keratin in your hair, but this only happens when the temperature of the curling iron reaches 240°C. It is very unlikely that your hair can reach this temperature during heat styling and the temperature of the hair is also about 15°C lower than what your styling tool indicates.
The problem is heat styling can damage the cuticle at very high temperatures (around 50-60°C). The cuticle protects the cortex of the hair which consists out of keratin. This leads to a rough and course feel of the hair. The hair also consists of about 10% of other lipid material other than keratin which is disrupted during heat styling.
What can you do to prevent hair damage from heat styling?
- Heat style your hair less often.
- Never use a curling iron on wet hair. Ironing wet hair can lead to ‘bubble hair’. Bubble hair is full of bubbles. When too much heat is applied to the hair, the water in the hair fiber converts into steam. When the steam tries to escape from the hair, it causes expansion of the hair, leading to a bubble structure.
- Make sure to blow dry at the lowest temperature possible.
- Use a product to protect your hair from heat damage.
- Make sure to use a conditioner before heat styling. Make sure the conditioner contains centrimonium chloride or centrimonium bromide.
How to choose a product that protects your hair from heat damage?
Many products mention the temperature up to which they provide heat protection. There are products that provide heat protection up to 446°C.
Now if the product doesn’t mention the heat protection limit, you can look for the following ingredients:
- Polymers: look for PVP/DMAPA acrylates copolymer polyquaternium-55/70.
- Silicone: They can provide protection at very high temperatures. Some examples are Dimethiconol, Cyclopentasiloxane, Amodimethicone, Silicone quaterium-22.
- Glycerin or propylene glycol can provide heat resistance to 150°C.
- Hydrolyzed wheat protein is another ingredient to look out for.