Have you ever wondered what’s that popping sound you hear when you iron your wet hair? Guess what? What’s happening in your hair fibers is exactly the same as when a popcorn pops. 

 Popcorn is great movie snacks because you can finish a movie and a bagful without feeling too full. This is because popcorn consists mostly of air. Eating 1 cup of popcorn is just equivalent to eating 20 kernels of corn, thanks for its porous structure.  

Inside a single kernel is water. When a popcorn is heated, water reaches its boiling point and starts to form in to steam (steam is water in its heated, gaseous state). Gas, as we all know, always finds its way out in a confined space by pushing against the walls of whatever it is contained (in this case the kernel shell). When there is too much pressure inside the kernel, the heated steam pops its way out, destroying the kernel shell. As it ruptures, extreme heat and pressure transforms the starch inside into a gelatinous material that rapidly solidifies as it cools. And so finally, there’s your white, brain-like snack called popcorn. 

When your hair is wet, water is trapped within the porous structure of your hair. A typical hair iron has a surface temperature of about 200 degrees Celsius, way above the boiling temperature of water (100 deg C). When trapped moisture is exposed to this temperature, it rapidly boils and turns in to steam. Steam then exerts pressure on the fibers of your hair, until your hair can no longer withstand and starts to break apart. The gaps or spaces that resulted from rapid vaporization of water creates a porous structure in your hair. Visualize a porous hair through this sponge.

This damage worsens with repetition. The next time you wet your hair, moisture penetrates deeper through spaces created by steam from previous damage and creates new, deeper damages. This further increases the hair’s porosity. Hair with high porosity is less stronger and is less able to keep moisture in. Porous hair holds so much water when is wet so it feels soft and gummy in the shower. However as the hair dries, water can easily escape and very little moisture is retained.  Apart from water, chemicals from different hair products is easy to penetrate within porous hair. (This is also the reason why damaged hair absorbs dye more quickly compared to healthy hair).

  That’s why your hairstylist always tell you to never iron your hair wet. Damage may not be very noticeable at first, but when you do it too frequently, it will eventually result to dry and brittle hair, caused by increased hair porosity.   So the next time you’ll iron your hair wet, you should probably think about popping popcorns.