The Deal

• $187 for one keratin smoothing treatment ($350 value)

Keratin Treatments: Microscopic Mane Maintenance

Learn more about what’s going on beneath the surface of your strands during this treatment with Groupon’s examination of keratin treatments.

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 what gives each head of hair its unique texture. For those who find their hair’s unique texture a pain to deal with every morning, those keratin bonds can be chemically rearranged with popular salon treatments from Brazilian Blowout or Keratin Complex.

Stylists apply a keratin-rich solution that finds its way into each hair’s second layer, where it can chemically reprogram hair from an unruly, cigarette-smoking strand into a well-behaved member of the scalp’s society. The heat of a flat-iron straightens hair after the serum’s application so that as the keratin molecules fuse to each strand, they’ll do so in the right position. Methylene glycol or formalin—which release formaldehyde under heat—typically function as the glue bonding the molecules during and after treatment. The result of all this chemistry is a straighter and smoother look that can last for two months or longer, and, although any heat-based treatment can be taxing on hair, its fortifying effects tend to leave hair glossier and more voluminous than other relaxers do. So although frizz disappears, waves or loose curls can continue to cascade across the shoulders.