What type of conditioner penetrates the cortex and reinforces the hair shaft from within?

A protein conditioner is specifically formulated to penetrate the hair's cortex, which is the inner layer of the hair shaft. By doing so, it reinforces the hair from within, helping to restore strength and resilience. This is particularly beneficial for hair that has been damaged or weakened by chemical processes, heat styling, or environmental factors. The proteins in these conditioners work to fill in gaps in the cuticle layer and bond with the hair's natural keratin, thereby improving the overall structure and integrity of each strand.

In comparison, while moisturizing conditioners primarily add hydration and smoothness to the outer layer of the hair, they do not penetrate as deeply as protein conditioners. Leave-in conditioners provide surface-level moisture and help with detangling and protection but lack the composition to penetrate deeply into the cortex. Deep conditioners, although they are designed to provide intensive moisture and nourishment, may not specifically focus on reinstating protein levels within the hair shaft like protein conditioners do.