Both lye and no-lye Relaxers are used to straighten African American hair. If either is used carelessly, it can cause severe damage to both the hair and the scalp. There are pros and cons to both types of relaxers. Know the facts before making a choice.
Lye relaxers are also known as sodium hydroxide relaxers. A lye relaxer is the strongest of the two chemical relaxers. A lye relaxer has a pH of 10 to 14. Users must beware of this higher pH, and approach use with caution. The higher the pH is, the faster it works - and the more damage it can to do if improperly used.
No-lye relaxers contain guanidine hydroxide. A no-lye relaxer is a strong relaxer, and can easily damage hair and scalp if not correctly applied. Damage can include but is not limited to breakage, thinning, scalp irritation, and hair loss.
The difference between the two relaxers is the chemical compound responsible for the hair-straightening action. In lye relaxers, this is sodium hydroxide, and in no-lye relaxers, it is guanidine - which comes from the same metal hydroxide family as sodium hydroxide. The higher pH balance of lye relaxers means they work fast and increase the risk of over-processing the hair.
The two relaxers require different preparations. Almost all no-lye relaxers will include a step in which you have to mix the crème and liquid part of the relaxer together; this is known as the activator step. Lye relaxers never have the activation step; they come ready to use. Also, no-lye relaxers can be used for only one application; if any is left over, it should be thrown away. Lye relaxers are good for more than one application.
Both no-lye and lye relaxers have downsides. You can end up with hair and scalp damage with both types of relaxers. When applying a relaxer at home it is usually a lot safer to apply a no lye relaxer, as it is the milder of the two. Applying a relaxer should always be approached with caution, and when you're not sure seek the help of a professional.