The difference between Lye and No-Lye Relaxers

Most relaxers contain either of these 2 active ingredients: Sodium hydroxide (Lye) or Calcium hydroxide (No lye). Lye relaxers usually come in a jar and don't require any mixing while no lye relaxers usually come in a kit with the relaxer, activator and other accessories. Both active ingredients work by breaking down the bonds of the hair. The key difference is the effect on the hair and scalp.

Lye Relaxers

Lye relaxers can be quite harsh on the scalp so if your scalp is sensitive, this may not be the best option for you. They also tend to process the hair faster which is great because it means that you don't have to leave the relaxer on as long as you would a no lye relaxer to get the same results. The major advantage of lye relaxers is the fact that it is much gentler on your hair than no lye relaxers. You hair is better able to absorb and retain moisture when you use a lye relaxer and is therefore healthier, stronger and less likely to break.

No Lye Relaxers

No lye relaxers have calcium hydroxide or guanidine hydroxide as the active ingredient. They are gentler on the scalp than lye relaxers but significantly harsher on the hair. No lye relaxers leave calcium deposits on the hair which prevents your hair from absorbing and retaining moisture properly. This leaves your hair dry and susceptible to breakage. To combat this, use a good clarifying shampoo regularly if you relax with a no lye relaxer. The clarifying shampoo will help remove the calcium buildup. However, in the process of removing the calcium deposits, it also strips and removes other nutrients from your hair so be sure to replenish by deep conditioning after clarifying.
 

Choosing which to use depends on the sensitivity of your scalp, how well your hair takes to relaxers, what your preferred outcome is (bone straight or texlaxed).

Tips for smooth relaxer day experience

Apply Relaxer to ONLY to new growth
Always make sure your hair is well detangled before relaxing
Always wait at least a week after washing  to relax your hair. 

Never use relaxers on a damaged scalp.

Touch ups (re-touch) should only be done between a periods of six to eight weeks. The more chemicals applied to the hair, the more possibility of damage.

Carry out a strand test to determine the best relaxers for your scalp.