Turning curly hair into straight or vice versa is not at all easy, since the initial data in our beauty genes are quite hereditary. We found out what happens to the hair when we change its structure!
If we were in chemistry class right now, we would see under a microscope that the hair consists of braided protein chains of keratin. They contain sulfur atoms — sulfides, forming a disulfide bond when combined. This connection is responsible for the hair shape. The fact is that curly hair is rich in disulfide bonds, but straight hair is not.
Hairdylists work as true magicians: determine your hair type, select the right solutions, keeping them on hair only for a particular period of time, and then apply some solutions again. The whole magic of the magical hair transformation from curly to straight and vice versa consists in breaking, adding and rearranging the disulfide bond. First, their own hydrogen sulfide and disulfide bridges between amino acid molecules and amino acid chains of hair are destroyed, then new ones are created (due to the keratin), and then all this is sealed.
First, alkaline composition is applied. It opens the cuticle layer of the hair and destroys (or adds) disulfide bonds in the hair. When the hair changes its structure, this composition washes off. Then the stylist applies acid neutralizer, restoring the pH balance.