What Is Keratin? It’s a protein that’s naturally in your hair.

How It Works: A stylist applies a keratin hair-straightening product to your hair and then uses the heat of a flat iron to seal it in. The process takes about 90 minutes or longer, depending on your hair’s length. Salon keratin products include Keratin Complex Smoothing Therapy by Coppola, Global Keratin Complex, the La-Brasiliana treatment, Brazilian Keratin Treatment, the Brazilian Blow-out, and Brazilian Hair Straightening.

Time-Saving Tresses: If you usually style your hair straight, a keratin hair-straightening treatment could shorten your blow-dry time by 40% to 60%. Farewell, Frizz: You can forget about frizzy hair after treatment. You could walk out in moist or light rain and your hair won’t change.

Wait before You Wash: You shouldn’t wash your hair for two or four days after getting the treatment. That’s because the solution takes time to work.

Upkeep: After you get a keratin hair treatment, and after the don’t-wash waiting period, you should use sodium-sulfate-free shampoo to help maintain the treatment. How Long It Lasts: Expect the results to last two to three months. Keratin is more of a restorative treatment, even if you have a good hair type, it still strengthens the hair shaft and makes your hair more resilient.