Which shampoo rehardens or locks newly straightened hair into its new shape?

• A. Neutralizing shampoo
• B. Clarifying shampoo
• C. Moisturizing shampoo
• D. Deep conditioning shampoo

Answer: (A)

The key idea is that the step which locks the newly achieved shape is the neutralizing action. After the hair has been treated to rearrange its internal bonds into a straightened form, the neutralizing shampoo stops the chemical process and re-forms the disulfide bonds in their new configuration. This rehardening of the bonds is what preserves the straight shape and prevents the hair from springing back. So the neutralizing shampoo is used precisely to set the new form by completing the chemical change and stabilizing the bonds.

Clarifying shampoo mainly removes buildup and residue, not the bond-reforming action that fixes the new shape. Moisturizing shampoo provides conditioning to soften and hydrate but doesn’t lock the hair into its straight form. Deep conditioning shampoo offers extra conditioning, which is beneficial but again does not establish the new bond configuration that holds the shape.