No Lye vs Lye Relaxer

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http://blackhair.about.com/od/permsrelaxers/p/lyevsnolyerelaxers.htm

The Great Lye vs. No-Lye Relaxer Debate:

When it comes to chemically straightening your hair, there can be some confusion about which products to use, especially when you're bombarded with shelves of boxes and promises of silky, flowing hair at every turn. Especially confusing can be knowing the difference between lye and no-lye relaxers. Here's the deal on chemical relaxers and how to find out which is best for you.

About Lye Relaxers:

The main, active ingredient in a lye-based relaxer is sodium hydroxide. The pH level is higher in a lye relaxer than a no-lye relaxer (approximately 12-14 for lye, 9-11 for no-lye, whereas your hair should generally have a pH of around 4-5). Does this higher pH make a lye relaxer worse for your hair?

A lye relaxer works to break down the hair's bonds more quickly, which is good because you often experience more scalp irritation with this chemical; the faster it works, the sooner you can rinse it out. However, these tend to rinse cleanly and quickly with a good neutralizing shampoo follow-up.

About No-Lye Relaxers:

The main, active ingredient in a no-lye based relaxer is calcium hydroxide or guanidine hydroxide. Although the pH level of a no-lye relaxer is typically lower than a lye-based one, no-lye relaxers are often associated with dryer hair due to potential calcium buildup. One of the major reasons someone may prefer a no-lye relaxer is if her scalp is sensitive, as the chemicals in this type of relaxer can be milder on the scalp. This doesn't mean that it's better to use on children or that the chemicals cannot burn you (they can).

Unfortunately, people sometimes make the mistake of leaving a no-lye relaxer on the hair for too long, leading to dry, dull hair due to over-processing. To remove calcium buildup, try a clarifying shampoo once a month or so to remove dull deposits. Since clarifying cleansers are often drying, a deep conditioning treatment should be a regular part of your hair care routine.

Bottom Line:

The bottom line is that all relaxers contain chemicals that break down the hair's natural bonds in order to straighten it and that one relaxer doesn't fit everyone's needs. It's best to consult with a professional to determine what your particular needs are when it comes to relaxers. And no, you cannot apply a lye relaxer over hair that's been processed with a no-lye relaxer (and vice versa)! However, you can apply a different relaxer to new growth if your current straightener isn't giving you the results you want. It's not recommended to constantly switch relaxer types or brands. Once you find the relaxer that works for you, it's best to stick with it until or unless it stops.