Keratin Treatments: Microscopic Mane Maintenance Learn more about what’s going on beneath the surface of your strands during this treatment Keratin is the molecular building block of human beauty—without this fibrous protein, humans wouldn’t have nails hard enough to polish, tooth enamel sturdy enough to withstand weekly brushings, or hair lush enough to style. Within each strand of hair, chains of keratin can be arranged in different molecular patterns, and this variation is