The Science Behind Heat Damage on Natural Hair

The Science Behind Heat Damage on Natural Hair


Heat damage is one of the leading hair challenges reported worldwide and within the Myavana Community. This is partially due to our desire to constantly change our hairstyles and have a new look for each week of the year. While this is not a bad thing, improper heat application management will cause more harm than good. This is why it is important to know the art behind proper heat application techniques and tools. In order to reduce the trauma, hair loss and extensive hair damage that might take months and years to remedy, we will provide you with the information necessary to mitigate this challenge so you will always have healthy, beautiful hair. 

Some of the major application tools we use are blow dryers, flat irons and curling irons. These tools can emit up to 100͒C of heat with the maximum being up to 450͒C. Now, if you know anything about temperature, you will know that the boiling point for water is within that stipulated range. Stay woke sisters! This is way more heat than is needed to achieve any look that requires heat. Some of the major issues we will look at today are hair dehydration, protein damage and water loss.

Dehydration/Water Loss

The rapid removal of water molecules from the hair is a direct threat to the health, viability  and longevity of your hair strands. Water molecules located within the cortex, both free and bound to keratin proteins, provide critical support to the structure and properties of your hair strand. Now, imagine losing the foundation of your house. What do you think would happen? If you guessed it, then you are right. It will fall to the ground. Our hair struction is the same and so losing the foundation necessary for our strands to thrive will directly result in breakage, weak or brittle hair and if not controlled properly can severely damage our strands from the scalp. Using excessive heat styling techniques will have this impact on your hair. Not only will the moisture be lost from your hair but the heat also significantly destroys the protein complex with the strands but can also distort your curl pattern, reduce curl memory and cause fizz. Dry, breaking hair is not the image we have in mind. We want bounce, body and shine. 

Protein Damage

Dehydration of hair is not the only consequence of unhealthy heat application. Heat is way more than the physical damage that is caused. Did you know that heat can denature the α-keratin and degrade the components of your hair cortex? This sounds like a hard pill to swallow so let’s break it down a bit. Your hair strand consists of three layers. The outlet layer is the cuticle and is made up of overlapping cells (similar to roofing shingles). These give the hair its sheen and provide protection to the inner layers due to their flatness and flexibility. 

The cortex is the layer in the middle and is the thickest layer. The cortex contains the hair color pigment melanin, and the hair shaper proteins keratin. These are what form the chemical bonds and chainlike structure (disulfide and hydrogen bonds) which retain moisture and strengthen the hair. Chemicals must be used in the forming or breaking of disulfides, permanently altering the hair structure. This is what happens when we use relaxers to straighten curly hair or perms to do the opposite.

Unlike disulfide bonds, hydrogen bonds are easily broken with weather or heat. This provides a temporary alteration of the shape of your hair. This is demonstrated when we use a curling iron to straighten our hair or when hair is wet and it appears straight until it dries. Finally, the layer on the interior is called the medulla and it provides strength like steel in a concrete column. But this layer can be missing in some light colored hair types.

Conclusion: If you are experiencing information overload, no worries. Myavana is here to break the science down into bite size pieces that are straightforward and chewable. We provide you with the tools and resources you need to achieve hair nirvana. If you have questions, send us an email at or book your consultation with one of our healthy hair experts.

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