Which chemical process alters the internal structure of hair?

The chemical process that alters the internal structure of hair is permanent waving. This process uses chemicals to break and reform the bonds within the hair structure, allowing the hair to be reshaped into curls or waves. During permanent waving, the disulfide bonds that give hair its strength and elasticity are chemically altered. After the hair is wrapped around rods and treated with a waving solution, these bonds are broken. The hair is then neutralized, which reforms the bonds in the new shape, creating the desired curl or wave.

In contrast, hair coloring does not significantly alter the hair’s internal structure; it primarily affects the cuticle and pigment molecules. Permanently straightening, while also changing the hair’s structure, focuses specifically on creating a straight shape, not curls or waves. Deep conditioning primarily serves to moisturize and repair the outer layer of hair without chemically altering its structural bonds.