Many clients want to know the difference between sodium hydroxide relaxers and no-lye (calcium hydroxide) relaxers. Well, the difference is the chemical makeup of the two. The sodium hydroxide relaxers are the more commonly used in professional salons. Sodium Hydroxide is the main chemical ingredient that straightens the hair, these relaxers have a less drying effect on the hair and they are usually only sold to licensed professionals. Although they are less drying on the hair, they do tend to irritate the scalp a bit more, causing the scalp to itch and burn faster than the calcium hydroxide (no lye) relaxers. The No Lye Relaxers contain Calcium Hydroxide and are less irritating on the scalp, causing less itching and burning during the relaxer process. Most Stylist's use no lye relaxers if a client informs them that they have a "sensitive scalp". I am personally not a fan of using no lye relaxers and do not offer them to my clients because the Calcium Hydroxide causes a...