Before there was straightening, there was “relaxing.†The first hair relaxing formulas on the market were very strong, containing sodium hydroxide and lye, according to Joico/ISO texture expert Francie Sorem. These relaxers tended to create surface damage on the hair. When a new category of product came along, it was called “straighteners†to distinguish these formulas from the relaxers.

In the past few years you've probably heard a lot about a Japanese straightening system. Sorem says the Japanese decided, instead of using lye, to try applying a perming solution to the hair, flat-ironing the hair and then neutralizing. “It's a six-hour service, but it gets the hair really flat and doesn't use sodium hydroxide or lye,†says Sorem. There can be a downside, she notes, saying, “You're pulling the hair flat while the bonds are stretched apart, so you still can do a lot of damage. The client can't have it more frequently than once every six months and can't get another service at the same time. In addition, typically a curling iron will not curl the hair after this process if the client wants a change.â€

In still a newer generation of products, Sorem says that ISO has created a formula “that will never make hair as straight as the Japanese straightener, but it does reduce 80 percent of the curl. The product is more flexible, because you can perm over it or blow it straight.â€