Relaxers Early 90's - Professional Use (Hair Chemical Guide)
Early in the 1800s hair relaxing products emerged, such as "G.A. Brandi’s hair Cream." Sale of "lye relaxers" began in 1917 by companies such as Proline. They also produced the first commercial "no lye relaxer" using potassium hydroxide in 1919.
A product falsely marketed as chemical-free in the 1990s, the Rio Hair Neutralizer System, led to a class action lawsuit against the manufacturer, the World Rio Corporation Inc, when the acidic chemicals it contained caused scalp damage and/or hair loss to thousands of users. The product was eventually withdrawn from the market.