The Truth About Relaxers
Although the first commercial brand of "lye" relaxer was not patented in the United States until 1971, legend has it that women had been applying soap with a heavy concentration of lye to their hair since the beginning of the 20th century for smoother and more manageable hair. Lye's active ingredient, sodium hydroxide, straightens the hair by loosening the curl as the hair fiber swells. Unfortunately, in order to achieve this, the caustic chemicals are actually breaking the bonds within the hair shaft, which will seriously weaken hair at best -- and can even break it off when used incorrectly.No-Lye Relaxers
In 1973 no-lye relaxers were introduced to the market. No-lye relaxers rely on ammonium thioglycolate instead of sodium hydroxide to loosen the hair's natural curl. Unlike sodium hydroxide, ammonium thioglycolate is more selective in changing the sodium bonds within the hair shaft. It will loosen the bonds within the hair shaft, rather than breaking them. But it's not damage-free; both lye and no-lye relaxers create a permanent change in hair, and all of the chemicals can potentially cause great damage. Both types of relaxers should only be applied by a professional with experience who takes the time to thoroughly assess the condition of your hair and scalp.