How does pH influence cuticle behavior during chemical processing?

• A. Higher pH opens the cuticle to allow processing; lower pH closes the cuticle, helping to lock in color and improve feel
• B. Higher pH closes the cuticle; lower pH opens
• C. pH has no effect on cuticle
• D. Higher pH seals cuticle to prevent processing

Answer: (A)

The main idea is that pH controls how the hair cuticle behaves during chemical processing. When the environment is alkaline (high pH), the cuticle scales lift and swell, increasing porosity so chemicals can penetrate and react. After processing, switching to acidic conditions (low pH) helps the cuticle lay down flat again, sealing the scales, which locks in color and improves feel. So, higher pH opens the cuticle to allow processing, and lower pH closes it to seal in the result. This matches how alkaline solutions enable treatment penetration and acidic finishes help set and smooth the hair.