Hair keratin treatments are popular for their ability to smooth and straighten hair, reduce frizz, and enhance shine. Here's a detailed overview of what you need to know about keratin treatments: What is a Keratin Treatment? Keratin is a protein that is naturally found in hair, skin, and nails. A keratin treatment involves applying a keratin-based product to the hair, which is then sealed in with heat using a flat iron. This process helps to repair damage, smooth the hair cuticle, and reduce frizz.