Which conditioner type is most likely to penetrate the cortex?

• A. Regular conditioners
• B. Leave-in sprays
• C. Clarifying shampoos
• D. Concentrated protein conditioners

Answer: (D)

The key idea is that deeper cortex repair requires proteins that can move beyond the surface and actually reach inside the hair shaft. Concentrated protein conditioners use hydrolyzed proteins, which have smaller molecular sizes. That allows them to penetrate through the cuticle layer and bind with the cortex, helping to reinforce internal structure and fill in gaps where damage has occurred. Regular conditioners mainly form a coating on the cuticle to smooth and seal the surface, without delivering enough protein deep into the shaft. Leave-in sprays are typically lighter and focus on surface conditioning, and clarifying shampoos are cleansing formulas that remove buildup rather than deposit proteins. So, the concentrated protein conditioner is the best option for potential cortex penetration because of its higher protein content and smaller, penetrating proteins.