In a keratin smoothing treatment (often simply called a "keratin treatment" or sold under brand names such as "Brazilian Blowout"), a keratin-based product is applied to the hair. Keratin is the structural protein that our hair is naturally made of. The product coats the hair fibre, smooths the raised cuticle layer and is then sealed into the hair with heat. The result is hair that is softer, shinier, noticeably less frizzy and faster to style. An important clarification: this is not a true permanent straightening that produces poker-straight hair forever, but a smoothing, frizz-reducing conditioning treatment that gradually washes out over time.
The salon appointment usually takes between 1.5 and 3 hours, depending on hair length and thickness. First, the hair is washed with a clarifying shampoo to remove residue and open the cuticle. The stylist then applies the keratin product section by section, lets it develop briefly and blow-dries the hair. The decisive step is sealing it with a flat iron: the stylist passes over the hair in many thin sections at a high temperature (roughly 200-230 °C depending on the formula) so the keratin bonds firmly. Some systems require that the hair not be washed or tied up for one to three days afterwards, while newer formulas allow immediate washing.
The treatment is best suited to frizzy, wavy, curly, thick or unruly hair that is hard to manage, as well as hair that looks stressed from heat styling and the environment. Fine, already very straight hair benefits less and can look flat under the weight of the product. Very tightly curled or afro-textured hair will not become bone-straight, but it will be far more defined, softer and easier to handle. One point worth raising is formaldehyde: classic keratin formulas released formaldehyde when heated. In Switzerland and the EU the permitted levels are strictly regulated; for home use and for pregnant women, formaldehyde-free products are expressly recommended, and it is worth specifically asking the salon for them.
Longevity is typically two to five months and depends heavily on aftercare. To extend the result you should use a sulfate-free and salt-free (sodium-chloride-free) shampoo, avoid washing too often, keep away from chlorinated and salt water and always use heat protection. The treatment grows out evenly, without a hard line at the roots, which makes it fade more discreetly than a chemical straightening. It can also be combined with hair colour, though colouring is ideally done before, or with some spacing from, the keratin treatment.
As a rough Swiss price guide (no guarantee, highly dependent on hair length, salon and region), a keratin smoothing treatment ranges roughly between CHF 150 and CHF 400, and higher for very long or dense hair. Since prices vary considerably from salon to salon, it pays to compare the hairdresser offers in your city before booking an appointment.