Brazilian hair straightening is a semi-permanent hair straightening method done by temporarily sealing a liquid solution consisting of formaldehyde or a formaldehyde derivative and a preservative solution into the hair with a hair iron.
The technique has many variations and is known by several other names and brands, including Brazilian Blowout, Breezilian straightening, Brazilian Keratin Treatment, BKT, and Keratin Cure. It is called Escova Progressiva in Brazil and Alisado brasileiro in Portugal.
The original formulation included formaldehyde or methylene glycol . The two products readily interconvert, and coexist in chemical equilibrium, when dissolved in water or body fluids. Since formaldehyde is a known health hazard, the compositions have been banned in several countries including Canada and the European Union. It is still performed in the United States, though there are regulations and have been controversies regarding the treatment.
Characteristics
Brazilian hair straightening treatments are meant to mostly or partially eliminate hair frizz and straighten curls and waves. They can be performed on all types of hair, whether natural or chemically treated (bleached, highlighted, colored, permed, relaxed or previously straightened).
The effect usually lasts about three months. Treatment must be repeated every few months to straighten the new hair growth.
Even though keratin treatment cannot last that long, you should treat your hair with keratin no more than three times per year. Too much keratin can damage hair, causing it to break off.
Process
The application technique is similar to the Japanese Yuko System, in that the hair is heated with flat irons to bind the product into the hair cuticle.
Depending on the treatment used, the customer may have to avoid washing, wetting, pinning or constraining the hair in any way (e.g. with hair clips, pony tails, or headbands) for some period after application, up to three days.
It is also confused or mistaken for keratina, another hair treatment.
The name "straightener" is arguably incorrect because it does not chemically alter the structure of the hair.
The formaldehyde controversy
Between 2010 and 2012, there was a dispute between the manufacturers and importers of Brazilian hair straightening products on one hand, and various US federal and state health agencies on the other, about the proper labeling and health warning of the products. The dispute centered about the chemical compounds formaldehyde () and methylene glycol (), which are the active ingredients of the process, responsible for binding the keratin to the hair. Formaldehyde is a gas that, when dissolved in water (including fluids in the human body), converts partially to methylene glycol. In the liquid, the two compounds coexist in a chemical equilibrium.
Regulations about formaldehyde levels
Formaldehyde in the air has long been recognized as a major occupational hazard in many industries; such as those using urea-formaldehyde (UF) adhesives, or UF-based products like fiberboard, and UFFI spray foam insulation. Levels below 0.05 parts per million (ppm) were found to be positively correlated with eye and nasal irritation. It has also been implicated in the development of childhood asthma, and, in 2006, the WHO International Agency for Research on Cancer (IARC) classified it as a 'known human carcinogen'.
Because of these concerns, since 1976 or earlier, European regulations on cosmetics banned products containing or releasing formaldehyde. Products containing any aldehydes more than 0.001% in leave-on products or 0.01% in rinse-off products were required to list the ingredients explicitly in their product labels.
The US Federal Occupational Safety and Health Administration (OSHA) sets a long-term permissible exposure limit (PEL) of 0.75 ppm of formaldehyde in the air, and a short term exposure limit of 2.0 ppm.